Physics Final
If the relative mass of a hydrogen atom is 1/4 that of a helium atom, how many hydrogen atoms would you need to equal the mass of four helium atoms?
16
What is the mass of an oxygen atom, O, in atomic mass units?
16 amu
Which has the greatest number of atoms?
16 g of methane, CH4
What is the mass of a water molecule, H2O, in atomic mass units?
18 amu
What is the formula mass of a molecule of C6H12O6?
180 amu
A ball with a mass of 2 kg rolls off a high table and hits the floor after 0.6 seconds. How high was the table?
2 m
What is the number of moles of H2O produced if you combust one mole of CH4 according to the following balanced equation? CH4 + 2 O2 → CO2 + 2 H2O
2 moles
How many moles of water, H2O, are produced from the reaction of 16 grams methane, CH4, with an unlimited supply of oxygen, O2. How many grams of H2O is this? CH4 + 2 O2 → CO2 + 2 H2O
2.0 moles of water, which is 36 grams
If you need 10 moles of sucrose, how many liters of a 4.0 molar solution would you need?
2.5 L
How many grams of sugar (sucrose) are there in 5 liters of sugar water that has a concentration of 0.5 grams per liter of solution?
2.5 g
What is the mass of an oxygen atom, O, in grams?
2.66 × 10-23 grams
A solid has a solubility at room temperature of 78 grams per liter. If 1.0 L of a hot solution containing 100. g of solute is cooled to room temperature, how much solid is formed?
22g
What is the number of grams of CO2 produced if you combust 0.50 mole of CH4 according to the following balanced equation? CH4 + 2 O2 → CO2 + 2 H2O
22g
The nucleus of an electrically neutral iron atom contains 26 protons. How many electrons does this iron atom have?
26
What is the mass of one mole of H2?
2g
How many different elements are in the compound C6H12O6?
3
How many molecules of sucrose are in a 0.5 moles of sucrose?
3.01 × 1023 molecules of sucrose
Two amu equals how many grams?
3.322 × 10-24 grams
Two projectiles are fired at equal speeds but different angles. One is fired at an angle of 30 degrees and the other at 60 degrees. With no air resistance, the projectile to hit the ground first will be the one fired at
30 degrees
What would the final temperature of a mixture of 30g of 30 degrees Celsius water and 30g of 60 degrees Celsius water
30 degrees Celsius
If an element has 15 protons and 16 neutrons and 15 electrons, what is the atomic mass of the element?
31
According to the following balanced chemical equation, if you want to generate two moles of H2O how many grams of O2 do you need? 2 H2 + O2 → 2 H2O
32
Which has the greatest number of molecules?
32 g of methane, CH4
What is the main difference between a conceptual model and a physical model?
A physical model represents the shape and form while a conceptual model describes how a system behaves.
Consider two planets in space that gravitationally attract each other. If the mass of one planet is doubled, and the distance between them doesn't change, then the force between them is
twice as much
To say that something is twice as hot as another suggests the hotter things has
twice the thermal energy
Considering how small atoms are, what are the chances that at least one of the atoms exhaled in your first breath will be your last breath?
very probable because of how incredibly small atoms are
Which of the following is an example of a physical change?
water boiling and being converted into steam
What are the formula masses of water, H2O; propene, C3H6; and 2-propanol, C3H8O?
water: 18 amu; propene: 42 amu; 2-propanol: 60 amu
Inside a freely falling elevator your
weight is zero
What is a chemical reaction?
when one or more new compounds are formed by rearranging atoms
Which of the following would be considered a homogeneous mixture?
wine
Is the head of a politician really made of 99.99999999% empty space?
yes
Does it make sense to say that a textbook is about 99.9% empty space?
yes, a textbook like all material things is made up of atoms, which are considered to be 99.9% empty space
Exothermic reactions are favored because they release heat to the environment. Would an exothermic reaction be more favored or less favored if it were carried out within a superheated chamber?
An exothermic reaction be less favored if it were carried out within a superheated chamber.
Which atom is smallest?
Be
Which color of light comes from the higher energy transition, red or blue?
Blue is a higher frequency and therefore corresponds to a higher energy level transition.
Someone argues that he or she doesn't drink tap water because it contains thousands of molecules of some impurity in each glass. How would you respond in defense of the water's purity, if it indeed does contain thousands of molecules of some impurity per glass?
Compared to the billions and billions of water molecules, a thousand molecules of something else is practically nothing.
A team of protons and a beam of neutrons of the same energy are both harmful to living tissue. The beam of neutrons is, however, less harmful. Why?
Neutrons carry no electric charge and this have a greater likeihood of passing through the tissue.
Based on atomic size, which would you expect to be more soluble in water: helium, He, or nitrogen, N2?
Nitrogen atoms are bigger and so nitrogen molecules should be more soluble in water due to greater dipole-induced dipole attractions.
Since atoms are mostly empty space, why don't objects pass through one another?
The electrons on the atoms repel other electrons on other atoms when they get close
What can be said about drinking water that is 99.9999 percent free of some poison, such as a pesticide?
The ratio of water molecules to pesticide molecules in the glass is so great that drinking the water is not problematic.
Oxygen, O2, has a boiling point of 90 K (-183°C), and nitrogen, N2, has a boiling point of 77 K (-196°C). Which is a liquid and which is a gas at 80 K (-193°C)?
Nitrogen is a gas, oxygen is a liquid at 80 K.
If all the molecules of a body remained apart of the body, would the body have any odor?
No, because there would be no molecules traveling to our nose.
The shell model presented in this book is not very accurate. Why then is it presented?
The shell model is simpler and easy to understand.
Oxygen atoms are used to make water molecules. Does this mean that oxygen, O2, and water, H2O, have similar properties?
No, compounds are uniquely different from the elements from which they're made.
What can you deduce about the activation energy of a reaction that takes billions of years to go to completion? How about a reaction that takes only fractions of a second?
The slow reaction must have a high activation energy while the fast reaction must have a low activation energy.
Some older cars vibrate loudly when driving at particular speeds. For example, at 65 mph the car may be most quiet, but at 60 mph the car rattles uncomfortably. How is this analogous to the quantized energy levels of an electron in an atom?
The vibrating car is analogous to one of the energy levels of the electron, which is the point at which the electron experiences resonance.
Steel wool wetted with vinegar is stuffed into a narrow mouth round glass bottle. A rubber balloon is then sealed over the mouth of the bottle. After several hours, the balloon inflates into the bottle in an inverted manner. What happened?
The vinegar reacts with the steel wool by absorbing oxygen within the bottle thus decreasing the pressure. The greater outside pressure causes the balloon to inflate in an inverted manner.
A skillet is lined with a thin layer of cooking oil followed by a layer of unpopped popcorn kernels. Upon heating the kernels all pop thereby escaping the skillet. Which of the following physical and/or chemical changes occurred?
The water within each kernel is heated to the point that it would turn into water vapor as the kernels popped (physical change). The starches within the kernels are cooked by the high temperatures (chemical change).
Is it possible to have a macroscopic sample of oxygen that has a mass of 14 atomic mass units?
No, this is less than than the mass of a single oxygen atom.
Oxygen, O2, is certainly good for you. Does it follow that if small amounts of oxygen are good for you then large amounts of oxygen would be especially good for you?
No. Breathing 100% oxygen for extended periods of time can be damaging to the body.
Should the periodic table be memorized? Why or why not?
No. The periodic table is a reference to be used, not memorized
Why are noble gases infinitely soluble in noble gases?
Noble gases can be mixed homogeneously in any proportion.
What property of an electron makes it possible to use electron microscopes?
They have shorter wavelengths than visible light.
Does a shell have to contain electrons in order to exist?
Two of the above are reasonable answers.
Why does oxygen have such a low solubility in water?
Water's attraction for itself is stronger than its attraction for oxygen molecules. Water and oxygen only attract one another by means of weak dipole-induced dipole attractions.
In what sense can you truthfully say that you are a part o every person around you?
We are continually exchanging our atoms
Why can't we see atoms?
We see with light energy and the wavelength is larger than the object and so it is not reflected.
How does the wave model of electrons orbiting the nucleus account for the fact that the electrons can have only discrete energy values?
When an electron wave is confined, it is reinforced only at particular frequencies.
Classify the following as a homogeneous mixture, heterogeneous mixture, element, or compound: table salt.
compound
Classify the following as element, compound, or mixture, and justify your classifications: table salt, stainless steel, table sugar, aluminum, ice.
compound; mixture; compound element; compound
Which of these properties describes a metal?
conducts heat very well
How can a hydrogen atom, which has only one electron, have so many spectral lines?
One electron can be boosted to many different energy levels.
You are given two samples of elements, and each sample has a mass of 10 grams. If the number of atoms in each of these samples is the same, what must be true of the two elements?
The elements are likely be located in the same position in the periodic table. The density of the two elements are the same. Their spectral patterns will likely be identical.
How are intermolecular forces and solubility related?
Solubility depends on the solvent's ability to overcome the intermolecular forces in a solid.
How does formula mass differ from atomic mass?
The formula mass of a substance is the sum of the atomic masses of the elements is its chemical formula. The atomic mass is the mass of a single atom.
If you were to increase the pressure of a gas above a liquid (such as by pressing a piston above a liquid) what happens?
The gas is forced into solution and the solubility increases.
If nitrogen, N2, were pumped into your lungs at high pressure, what would happen to its solubility in your blood stream?
The greater the pressure, the greater the solubility.
Which has more atoms: 17.031 g of ammonia, NH3, or 72.922 g of hydrogen chloride, HCl?
The have about the same number of atoms.
What chemical change occurs when a wax candle burns?
The heated wax molecules combine with oxygen molecules.
When we breathe we inhale oxygen, O2, and exhale carbon dioxide, CO2, plus water vapor, H2O. Which likely has more mass, the air that we inhale or the same volume of air we exhale? Does breathing cause you to lose or gain weight?
The air we exhale has more mass; Breathing causes you to lose weight.
Why are the atomic masses listed in the periodic table not whole numbers?
The atomic masses are average atomic masses.
A friend argues that if mass were really conserved he would never need to refill his gas tank. What explanation do you offer your friend?
The atoms (mass) of gasoline are converted into exhaust fumes.
Steel wool wetted with vinegar is sealed within a balloon inflated with air. After several hours, what happens to the volume of the balloon?
The balloon deflates.
Fish don't live very long in water that has just been boiled and brought back to room temperature. Suggest why.
The boiling process removes the air that was dissolved in the water. Upon cooling the water is void of its usual air content, hence, the fish drown.
What is the difference between a compound and a mixture?
The components of a mixture are not chemically bonded together.
A cat strolls across your backyard. An hour later, a dog with its nose to the gourd follows the trail of the cat. Explain what is going on from a molecular point of vie.
The dog is smelling molecules from the cat
Half-frozen fruit punch is always sweeter than the same fruit punch completely melted because
crystallization is a purifying process.
Which of the following would be considered a physical property?
density
Which of the following would be considered applied research?
determining the lightest and strongest metal to be used for an airplane wing
If Earth's mass doubled with no change in radius, your weight would
double
If your mass remained the same while the mass of the Earth was doubled while staying the same size, your weight would
double
The ________ represents the complete range of frequencies of light energy from radio waves to cosmic rays.
electromagnetic spectrum
Surrounding the nucleus are the tiny
electrons
Any material made of only one type of tam is classified as an
element
Which of the following statements describes an isotope?
element with the same number of protons but a different number of neutrons
What are metalloids?
elements that have some properties like metals and some like nonmetals
Is the synthesis of ozone, O3, from oxygen, O2, an example of an exothermic or endothermic reaction?
endothermic because ultraviolet light is absorbed during its formation
An electron de-excites from the fourth quantum level to the third and then directly to the first. Two frequencies of light are emitted. How do their combined energies compare to the energy of the single frequency that would be emitted by de-excitation from the fourth level directly to the first level? Answer: The combined energies of the two frequencies emitted by the one electrons is
equal to the energy of the single frequency.
Which of the following would be considered basic research?
examining why a mouse likes cheddar cheese more than swiss cheese
An Earth satellite is in an elliptical orbit. The satellite travels slowest when it is
farthest from earth
If you filter sea water to remove all of the particles you would be left with a clear ________.
homogeneous mixture called a solution
When blue food coloring is stirred into water, the result is a ________.
homogeneous mixture called a solution
Chemistry is the study of ________.
matter and transformations of matter
How would you describe the size of the following object? a blood cell
microscopic
If an element has 10 protons and 11 neutrons and 10 electrons, which expression correctly identifies the element?
neon-21
The portion of the atmosphere that filters out 95 percent of the incident UV radiation is the ________.
ozone layer
The repeating trends that take place when examining the elements are called ________.
periodicity
Each night you measure your height just before going to bed. When you arise each morning, you measure your height again and consistently find that you are 1 inch taller than you were the night before but only as tall as you were 24 hours ago! Is what happens to your body in this instance best described as a physical change or a chemical change?
physical change because it readily reverses
Would you use a physical model or a conceptual model to describe the following: the brain; the mind; the solar system; the beginning of the universe?
physical; conceptual; physical; conceptual
Which of the following describes a nonmetal?
poor conductor of electricity
Which of the following would be considered a chemical property?
reactivity towards water
Which of the following elements will most likely be shiny and flexible?
rhodium (Rh)
A projectile is fired vertically from the surface of the Earth at 8 km/s and remains in a vertical path. The projectile will
rise and fall back to Earth's surface
Which of the following would be considered a heterogeneous mixture?
salad dressing
Which of these is not a metal?
selenium (atomic no. =34)
For each degree a volume of air at 0 degrees is called, its volume,
shrinks by 1/273
Which of the following elements is a transition metal?
silver (Ag)
A refrigerator delays the spoilage of food by
slowing down the rate of chemical reactions within microorganisms.
What is the name of the following compound? NaF
sodium fluoride
Using the following generic atom description, choose the correct method for determining the number of neutrons. F G X
subtract G from F
In a solution made from one teaspoon of sugar and one liter of water, which is the solute?
sugar
What is the name of the following compound? SF3
sulfur trifluoride
Which of the following would not be considered a physical property?
temperature at which a material catches on fire
Which chemical family is composed almost entirely of man-made elements?
the actinides
When we breathe, we inhale oxygen, O2, and exhale carbon dioxide, CO2, plus water vapor, H2O. Which likely has more mass: the air we inhale or the same volume of air we exhale?
the air we exhale
Which of the following could NOT be represented by a conceptual model?
the floor plan of a house
What property primarily determines the effect of temperature on the solubility of gas molecules?
the kinetic energy of the gas
The atomic symbol comes from
the letters of the element's name
What is the activation energy?
the minimum amount of energy to break the bonds in reactants
How might the spectrum of an atom appear if its electrons were not restricted to particular energy levels?
A broad spectrum of all colors would be observed.
What is the approximate mass of a carbon atom in atomic mass units (amu)? How about a carbon dioxide molecule?
A carbon atom has a mass of about 12 amu. Carbon dioxide would then have a mass of 44 amu.
Mixtures can be separated into their components by taking advantage of differences in the chemical properties of the components. Why might this separation method be less convenient than taking advantage of differences in the physical properties of the components?
A chemical property involves a chemical change so that you no longer have what you had.
What is the difference between a compound and a mixture?
A mixture can be physically separated into its components; a compound cannot be physically separated into its components.
What is the valence shell?
It is the outermost shell of electrons in an atom.
What is a reaction rate?
It is the speed at which reactants are consumed or product is formed.
If it takes energy to break bonds and you gain energy in the formation of bonds, how can some reactions be exothermic while others are endothermic?
It is the total amount of energy that matters. Sometimes some bonds are stronger than others and so you gain or lose energy when you form them.
How does a catalyst increase the rate of a reaction?
It lowers the activation energy.
Why is it important for a chemist to know the relative masses of atoms?
It provides information about how many atoms two samples have relative to each other
If water is added to 1 mole of sodium chloride in a flask until the volume of the solution is 1 L, what is the molarity of the solution?
M= 1 M
What is the molarity when water is added to 2 moles of sodium chloride to make 0.5 L of solution?
M= 4M
Which element has the atomic number 12?
Mg
For the following balanced reaction, which of the following is a solid? 2 Na(l) + Cl2(g) → 2 NaCl(s)
NaCl
How would you classify the following material? milk
a suspension
If a neutral element has 8 neutrons and 7 electrons, which expression correctly identifies the element?
15N 7
The lowest temperature possible in nature is
-273 degrees Celsius
If you need 3.01 × 1023 molecules of sucrose, how many liters of a 4.00 molar solution would you need?
0.125 L
Which of the following solutions is the most dilute?
0.2 liter of water with 2 grams of sugar 0.5 liter of water with 5 grams of sugar 0.1 liter of water with 1 gram of sugar 1 liter of water with 10 grams of sugar They all have the same concentration.
Which of the following solutions is the most concentrated?
0.5 liter of water with 50 grams of sugar
How many moles of sugar, C12H22O11, are there in 200. grams?
0.585 moles
According to the following balanced chemical equation, if you want to generate two moles of H2O, how many moles of O2 do you need? 2 H2 + O2 → 2 H2O
1
What is the number of moles of H2O produced if you combust 0.5 mole of CH4 according to the following balanced equation? CH4 + 2 O2 → CO2 + 2 H2O
1 mole
Which of the following has the greatest number of particles?
1 mole of Be 1 mole of Na 9.012 g of Be 22.990 g of Na All are the same
Which of the following has the greatest mass?
1 mole of Pb
Balance the following chemical equation. ____ N2 + ____ H2 → ____ NH3
1, 3, 2
A sample of water that is 99.9999 percent pure contains 0.0001 percent impurities. Consider from Chapter 1 that a glass of water contains on the order of a trillion trillion (1 × 1024) molecules. If 0.0001 percent of these molecules were the molecules of some impurity, about how many impurity molecules would this be?
1,000,000,000,000,000,000 (one million trillion: 1 × 1018)
Which is greater: 1.01 amu of hydrogen or 1.01 grams of hydrogen?
1.01 grams of hydrogen is greater than 1.01 amu of hydrogen
Which has the greater mass: 1.204 ×1024 molecules of molecular hydrogen or 1.204 ×1024 molecules of water?
1.204 ×1024 molecules of water
If it takes 20 beryllium atoms to equal the mass of two krypton atoms, what is the relative mass of beryllium compared to krypton?
1/10
If it takes three carbon atoms to equal the mass of one chlorine atom, what weight of chlorine do you need to equal the number of atoms in one kilogram of carbon?
1/3 of a kg
If it takes three golf balls to equal the mass of one tennis ball, what mass of tennis balls do you need to equal the number of golf balls in one kilogram of golf balls?
1/3 of a kg
If it takes 200 golf balls to equal the mass of four bowling balls, what is the relative mass of bowling balls to golf balls?
1/50
About how many elements do you have access to as a consumer of market goods.
10
If the relative mass of a pingpong ball is 1/20 that of a golf ball, how many golf balls would you need to equal the mass of 200 pingpong balls?
10
What is the molarity of 0.5 liters of a solution with five moles of sucrose in it?
10 molar
Boron has primarily two isotopes, one with an atomic mass of 11 amu and another with an atomic mass of 10 amu. If the abundance of the boron atom with a mass of 11 amu is 18.9 percent and the abundance of the other isotope is 81.1 percent, what would be the average mass of the boron atom?
10.19 amu
Escape speed from Earth is
11.2 km/s
The relative mass of carbon is 3/8 that of an oxygen molecule. How many grams of carbon are needed to have the same number of particles as found in 32 grams of oxygen molecules?
12g
The isotope chlorine-35 has a mass of 34.969 amu, and the isotope chlorine-37 has a mass of 36.966 amu. Given that 75.5% of all chlorine atoms found in mature are chlorine-35 and 24.5% are chlorine-37, find the atomic mass of chlorine, Cl (atomic number 17).
34.458
What is the sum of the atomic masses of all the atoms in sucrose, C12H22O11?
342 amu
If the solubility of a compound is 72 grams per liter, how many grams of the compound will dissolve in 0.50 liters?
36g
Balance this equation: −−H2(g)+−−N2(g)→−−NH3(g)
3H2(g)+N2(g)→2NH3(g)
If you have two molecules of TiO2, how many oxygen atoms would you have?
4
What is the molarity when water is added to 2 moles of sodium chloride to make 0.5 liter of solution?
4 M
How many grams of water, H2O, and propene, C3H6, can be formed from the reaction of 6.0 g of 2-propanol, C3H8O? C3H8O → C3H6 + H2O 2-Propanol Propene Water
4.2 grams of propene, 1.8 grams of water
What is the formula mass of a molecule of CO2?
44 amu
How many grams of sodium chloride are needed to make 15 L of a solution that has a concentration of 3.0 g per liter of solution?
45g
If you mix 50g of 40 degree Celsius water with 25g of 60 degrees Celsius water, the final temperature would be
47 degrees Celsius
Small samples of oxygen gas needed in the laboratory can be generated by any number of simple chemical reactions, such as 2 KClO3 (s) → 2 KCl (s) + 3 O2 (g) What mass of oxygen (in grams) is produced when 122.6 g of KClO3 (formula mass = 122.6 amu) takes part in this reaction?
48.00 grams
Balance this equation: −−Fe(s)+−−O2(g)→−−Fe2O3(s)
4Fe(s)+3O2(g)→2Fe2O3(s)
How many atoms of Oxygen (O) are in H3OClO4
5
How many oxygen molecules are needed to make 10 carbon dioxide molecules according to the following balanced chemical equation? 2 CO + O2 → 2 CO2
5
A stone is thrown horizontally from the top of a cliff. One second after leaving your hand it drops a vertical distance of
5 m
How many moles of water are there in 100. grams of water?
5.55 moles
If the relative mass of a hydrogen atom is 1/4 that of a helium atom, how many helium atoms would you need to equal the mass of 200 hydrogen atoms?
50
Increasing the temperature of 50 grams of water by 1 degree Celsius requires
50 calories
Which of the following reaction energies is the most endothermic?
540 kJ/mole
How many bonds between nitrogen and hydrogen are formed if you react nitrogen with hydrogen according to the following reaction? N2 + 3H2 → 2 NH3
6
If a neutral element has the following chemical notation, how many electrons does it have? carbon-13
6
If a neutral element has the following chemical symbol, how many electrons does it have? 18 6 O
6
How many molecules of sucrose are in 0.5 L of a 2 molar solution of sucrose?
6.02 × 1023 molecules of sucrose
If the relative mass of a pingpong ball is 1/20 that of a golf ball, how many pingpong balls would you need to equal the mass of two golf balls?
6.022 × 1023
The isotope lithium-7 has a mass of 7.0160 atomic mass units, and the isotope lithium-6 has a mass of 6.0151 atomic mass unites. Given the information that 92.58 person of all lithium atoms found in nature are lithium-7 and 7.42 percent are lithium-6, calculate the atomic mass of lithium, Li (atomic number3).
6.942
How many grams of gallium are there in a 145 gram sample of gallium arenside, GaAs?
69.7 g
How many atoms are in one molecule of Na2SO4?
7
A projectile is launched at an angle of 15 degrees above the horizon and lands downrange. With no air resistance, what other projection angle for the same speed would produce the same downrange distance?
75 degrees
An element found in another galaxy exists as two isotopes. If 80.0 percent of the atoms have an atomic mass of 80.00 atomic mass units and the other 20.0 percent have an atomic mass of 82.00 atomic mass units, what is the atomic mass of the element?
80.4 atomic mass units
If a neutral element has the following chemical notation, how many electrons does it have? fluorine-19
9
How many grams of water can be formed from the reaction between 10 grams of oxygen and 1 gram of hydrogen?
9 grams of water are formed because oxygen and hydrogen react in an 8:1 ratio.
If a neutral element has the following chemical symbol, how many electrons does it have? 235 92 U
92
An atom absorbs or emits only particular frequencies of light. White light bends into a glass prism and separates into a rainbow of colors. In which of these two scenarios does the electromagnetic radiation behave as a wave? As a particle?
Absorption of light shows particle behavior while bending of light shows wave behavior.
What do the components of a conceptual model have in common?
All components interact with each other.
Is chemistry the study of the submicroscopic, the microscopic, or the macroscopic, or all three?
All of the above because most everything is made of atoms and molecules.
In the winter Vermonters make a tasty treat called "sugar on snow" in which they pour boiled-down maple syrup onto a scoop of clean fresh snow. As the syrup hits the snow it forms a delicious taffy. Which of the following changes are involved in the making of sugar on snow?
All of the above changes are involved in the making of sugar on snow.
How does a suspension differ from a solution?
Although a solution and suspension are both homogeneous mixtures, only the components of a suspension will separate by spinning the mixture in a centrifuge.
Which of the following statements is false?
An atom emits electromagnetic radiation when an electron moves from a lower energy level to a higher energy level.
Which of the following best explains what is happening when an atom emits light?
An electron is dropping from a higher to a lower energy level with the difference in energy between the two being emitted as light.
Are the chemical reactions that take place in a disposable battery exothermic or endothermic? Is the reaction going on in a rechargeable battery while it is recharging exothermic or endothermic?
An operating disposable battery is driven by exothermic reaction, while a recharging rechargeable battery is driven by endothermic reactions.
How is the solubility of a gas affected by temperature?
As temperature goes down, the solubility goes up.
How is the solubility of a solid affected by temperature?
As temperature goes up, the solubility goes up. As temperature goes down, the solubility goes down.
The boiling point of methanol is 65°C and the boiling point of ethanol is 78°C. Which of the following statements is true?
At 70°C you would have methanol gas and liquid ethanol.
Which element would have chemical properties the most similar to chlorine (Cl)?
Br
The element bromine, Br (atomic number 35), has two major isotopes of similar abundance, both around 50%. The atomic mass of bromine is reported in periodic table as 79.904 amu. Choose the most likely set of numbers for these two bromine isotopes.
Br-79, Br-81
Which of the following elements are in the same group as silicon (Si)?
C
Which is heavier: a water molecule, H2O, or a carbon dioxide molecule, CO2?
CO2
If two protons and two neutrons are removed from the nucleus of an oxygen atom, a nucleus of which element remains?
Carbon-12
Which of the following elements are in the same period as magnesium (Mg)?
Cl
For the following balanced reaction, which of the following is a gas? 2 Na(l) + Cl2(g) → 2 NaCl(s)
Cl2
Germanium, Ge (atomic number 32), computer chips operate faster than silicon, Si (atomic number 14), computer chips. So how might a gallium, Ga (atomic number 31), chip compare with a germanium chip?
Computer chips manufactured from gallium, operate faster than chips manufactured from germanium.
Which of the following describes the term concentration?
It is the amount of solute in a given amount of solution.
An object is laced halfway between the Earth and the Moon. The object will fall toward the
Earth
In some instances electromagnetic radiation behaves like a wave. In other instances electromagnetic radiation behaves more like a particle. Which behavior more accurately describes the true nature of electromagnetic radiation?
Electromagnetic radiation behaves both as a wave or as a particle depending on the circumstance.
Which contributes more to an atom's size?
Electrons
What was Niels Bohr's explanation for the observation of atomic spectra?
Electrons could only move in discrete energy steps within an atom.
What is the main tenet of Plank's quantum hypothesis?
Energy comes in discrete packets of a certain minimum size.
Which of the following statements best describes the concept of entropy?
Energy has a tendency to disperse.
Which equations are balanced? a) Mg (s) + 2HCl (aq) → MgCl2 (aq) + H2 (g) b) 3Al (s) + 3 Br2 (l) → Al2Br3 (s) c) 2HgO (s) → 2 Hg (l) + O2 (g)
Equations "a" and "c" are balanced.
Use the bond energies below to determine whether the following reaction is exothermic or endothermic: H2 + Cl2 → 2 HCl H-H (bond energy: 436 kJ/mol) Cl-Cl (bond energy: 243 kJ/mol) H-Cl (bond energy: 431 kJ/mol)
Exothermic with more than 50 kJ of energy released.
Which element has the atomic number 9?
F
Many people hear about atmospheric ozone depletion and wonder why we don't simply replace that which has been destroyed. Knowing about CFCs and how catalysts work, explain how this would not be a lasting solution.
Governments would be too slow to respond as they argued about who should shoulder the burden of undertaking such an endeavor. The amount of energy required to create and transport sufficient ozone to the stratosphere would be cost prohibitive. Any ozone we placed into the stratosphere would be destroyed by the same catalytic action that destroys naturally occurring stratospheric ozone.
For the following balanced equation, which has the highest coefficient? 4 H2 + 2 C → 2 CH4
H2
What is the chemical formula for the compound dihydrogen sulfide?
H2S
Hydrogen chloride, HCl, is a gas at room temperature. Would you expect this material to be very soluble or not very soluble in water?
HCl is very soluble in water.
How is it possible to deduce the identity of an element from its electron configuration?
If the atom is electrically neutral, the number of electrons corresponds to the atom's atomic number.
An Alka-Seltzer antacid tablet bubbles vigorously when placed in water but only slowly when placed in an alcoholic beverage of the same temperature containing a 50:50 mix of alcohol and water. Propose a probable explanation involving the relationship between the speed of a reaction and molecular collisions.
In a 50:50 mix there are fewer water molecules for the antacid molecules to collide with.
Bond energies increase in going from C-N (lowest) to C-O to C-F (highest). Explain this trend based upon the atomic sizes of these atoms as deduced from their positions in the periodic table.
In going from nitrogen to oxygen to fluorine the atoms get smaller. This means that the bonding atoms are closer together, which translates into a greater bond energy.
Where did the atoms that make up a newborn baby originate?
In the explosions of ancient
If you remove two protons and two neutrons from a gold atom (Au), what new element is formed (if any)?
Ir
Which of the following statements accurately describes the action of ozone?
It absorbs UV radiation and undergoes fragmentation.
How is ozone produced in the upper atmosphere?
It forms by reaction of oxygen molecules with UV light.
Which of the following does not describe a neutron?
It has a positive charge equivalent but opposite of an electron's.
What is an endothermic reaction?
It is a reaction where there is a net adsorption of energy from a reaction. It is a reaction that requires heat as a reactant. It is a reaction where the products have more energy than the reactants.
What is a chemical equation?
It is a shorthand notation for illustrating a chemical reaction.
What statement best describes a mole?
It is a very large number chemists use to count atoms or molecules.
Why do the natural reactions involving ozone not lead to depletion of the ozone layer?
Ozone breaks into fragments that can reassemble into more ozone. UV radiation generates more ozone.
Which of the following statements about ozone is true?
Ozone in the troposphere is a pollutant. Ozone in the stratosphere is beneficial.
Which contributes fore to an atom's mass: electrons or protons?
Protons
Which contributes more to an atom's mass: electrons or protons? Which contributes more to an atom's size?
Protons contribute more to an atom's mass while electrons contribute more to its size.
Which atom is largest?
Rb
Suggest why sodium chloride, NaCl, is insoluble in gasoline. Consider the electrical attractions.
Salt is composed of ions that are too attracted to themselves. Gasoline is non-polar so salt and gasoline will not interact very well.
If you remove two protons and two electrons from a sulfur atom (S), what new element is formed?
Si
Many solvents expand to occupy greater volumes with increasing temperature. What happens to the concentration of a solution made with such a solvent as its temperature is increased?
Since concentration depends on how much mass is dissolved in a given volume, as the volume increases, the concentration decreases.
Deuterium oxide, D2O, and water, H2O, have the same chemical structure and differ only in that D2O possesses the deuterium isotope of hydrogen, whereas water possesses the protium isotope. Deuterium oxide, also known as "heavy water," is 11 percent heavier than water. Might you expect its boiling temperature also to be about 11 percent greater? Why or why not?
Since they have the same chemical structures, there is a similar molecular attraction between the molecules, so their boiling temperatures are similar.
The air that a scuba diver breathes is pressurized to counteract the pressure exerted by the surrounding water. Under these conditions, excessive amounts of nitrogen dissolves in bodily fluids, such as blood. If the diver ascends to the surface too rapidly, the excessive nitrogen bubbles out of the bodily fluids-much like carbon dioxide bubbles out of a soda immediately after its has been opened. This results in a painful and potentially lethal medical condition known as the bends. Why does breathing a mixture of helium and oxygen rather than air help divers to avoid getting the bends?
The helium is less soluble in the bodily fluids and so less dissolves for a given pressure. Upon decompression, there is less helium to "bubble out" and cause potential harm.
An element has two different isotopes: one that weighs 65 amu and another that weighs 67 amu. If the average atomic mass of all the isotopes is 66.5 amu, what can be said about the relative abundance of the isotopes?
The isotope with the mass of 67 is more abundant than the isotope with the mass of 65.
What do members of the Chemical Manufacturers Association pledge in the Responsible Care program?
The members pledge to manufacture without causing environmental damage.
Why might increasing the temperature alter the rate of a chemical reaction?
The molecules will have a higher kinetic energy and bump into one another harder.
Evidence for the existence of neutrons did not come until many years after the discoveries of the electron and the proton. Give a possible explanation.
The neutron lacks an electrical charge.
Why isn't dirt listed in the periodic table?
The periodic table lists only elements made of one kind of material. Dirt is a mixture of elements and compounds.
Which is higher in an endothermic reaction: the potential energy of the reactants or the potential energy of the products?
The potential energy of the products is higher than the potential energy of the reactants.
What happens to the properties of elements across any period of the periodic table?
The properties of the elements gradually change across any period of the periodic table.
What does the following element description actually mean? 238 92 U
a uranium atom with 92 protons and 146 electrons
Why can't the elements of a compound be separated from one another by physical means?
Their atoms are too tightly bound to one another.
What do the electron configurations for all the group 18 noble gases have in common?
Their outermost occupied shells are filled to capacity.
How do we account for the great variety of substances in the world?
There are many possible combinations of atoms
Why does a glowing splint of wood burn only slowly in air, but rapidly in a burst of flames when placed in pure oxygen?
There is a greater number of collisions between the wood and oxygen molecules.
Why is there a drastic reduction in ozone in the spring?
There is a sudden increase in Cl atoms in the spring.
Why does iodine, I2 (s), spontaneously sublime at room temperature?
There is an increase in entropy as solid iodine, I2 (s), sublimes into iodine vapor, I2 (g), because in the gaseous phase energy is more readily dispersed.
Would you expect to find more dissolved oxygen in polar or tropical ocean waters? Why?
There would be more dissolved oxygen in the polar oceans because the solubility of oxygen in water decreases with increasing temperature.
When you set a pot of tap water on the stove to boil, you'll often see bubbles start to form well before boiling temperature is ever reached. Explain this observation.
These initial bubbles are the gases that were dissolved in the water coming out of solution. The solubility of gases in water decreases with increasing temperature.
Since some of the compounds that are destroying ozone are found in nature normally, how is it possible to tell that the reactive molecules destroying the ozone are due to our actions?
They are accompanied by compounds that are only man-made.
What do chicken noodle soup and garden soil have in common?
They are both examples of heterogeneous mixtures.
What are older, the atoms in the body of an elderly person or those in the body of a baby?
They are the same age, which is appreciably older than the solar system.
What is the main difficulty in trying to eliminate chlorinated fluorocarbons from the atmosphere?
They are very stable and take a long time to decompose completely.
Which of the following might best explain the reason why electrons are restricted to certain energy levels in an atom?
They behave like restricted waves and are self-reinforcing.
Wild plants readily grow "all by themselves" yet the molecules of the growing plant have less entropy than the materials used to make the plant. How is it possible for a there to be this decrease in entropy for a process that occurs all by itself?
Wild plants don't grow "all by themselves." When we consider the entire system, including the sun, we find an overall increase in entropy.
Given the following generic chemical reaction, which is the reactant? X → Y
X is the reactant.
Given the following generic chemical reaction, which is the product? X → Y
Y is the product.
Why might increasing the concentration of a set of reactants increase the rate of reaction?
You have increased the chances that any two reactant molecules will collide and react.
How would you describe light generated by heating pure elements if it was observed through a prism or spectroscope?
You would see a series of very sharp lines of emitted light.
Which has more atoms: a 1-gram sample of carbon-12 or a 1-gram sample of carbon-13?
a 1-gram sample of carbon-12
Which of the following could be represented by a physical model?
a cell
Classify the following as a homogeneous mixture, heterogeneous mixture, element, or compound: planet Earth.
a heterogeneous mixture
How would you classify the following material? a cappuccino (with foam)
a heterogeneous mixture
Classify the following as a homogeneous mixture, heterogeneous mixture, element, or compound: blood.
a homogeneous mixture
What does the following element description actually mean? hydrogen -2
a hydrogen with one neutron and one proton
Which of the following statements best describes an element?
a mateial consisting of only one type of atom
Which statement best describes a compound?
a material that is made up of a combination of atoms bonded together
Which of the following best describes a conceptual model of an atom?
a model that illustrates the tendency of an atom to undergo radioactive decay and the products it produces
Which has the most atoms?
a mole of gold a mole of lead a mole of helium All of the above have the same number of atoms.
The following statement describes which subatomic particle best? It does not have an electrical charge.
a neutron
Water and ethanol can be separated by heating the ethanol until it boils away from the water. What type of change is this?
a physical change
The following statement describes which subatomic particle best? It has a relatively large mass.
a proton and a neutron
The following statement describes which subatomic particle best? It is a nucleon.
a proton and a neutron
Which of the following is not a chemical change?
a rock being crushed to powder
How would you classify the following material? coffee (black)
a solution
How would you classify the following material? coffee (with milk)
a suspension
What is the formula mass of sulfur dioxide, SO2?
about 64 amu
The ________ is what needs to be overcome in a reaction so that it can proceed to the products.
activation energy
Which of the following is a mixture?
air
The systematic names for water, ammonia, and methane are dihydrogen monoxide, H2O; trihydrogen nitride, NH3; and tetrahydrogen carbide, CH4. Why do most people, including chemists, prefer to use the common names for these compounds?
all of the above
Which of the following can be classified as matter?
all of the above
Which of the following is a property of light?
all of the above
Which of the following statements about electrons is true?
all of the above
Which of the following statements describes a saturated solution?
all of the above
The following statement describes which subatomic particle best? It is located outside of the nucleus.
an electron
The following statement describes which subatomic particle best? It is electrically charged.
an electron and a proton
What does the following element description actually mean? 18 6 O
an oxygen atom with 6 protons and 12 neutrons
A combination of two or more substances in which they no longer retain their chemical properties is called a(n) ________.
compound
Which of the following is a metalloid?
antimoney (atomic no. =51)
Which of the following elements is a gas at room temperature?
argon (Ar)
If an element has 18 protons and 20 neutrons and 18 electrons, which expression correctly identifies the element?
argon-38
The international space station orbits at an average 360-km altitude so that it is mainly above Earth's
atmosphere
If an atom has 43 electrons, 56 neutrons, and 43 protons, what is its approximate atomic mass? What is the name of this element?
atomic mass, 99 amu, Technetium
Protons and neuters are bound together at the atom's center to form a larger particle the
atomic nucleus
Which of the following is a pure substance?
baking soda
What is the chemical name for a compound with the formula Ba3N2?
barium nitride
You could swallow a capsule of germanium, Ge (atomic number 32), without significant ill effects. If a proton were added to each germanium nucleus, however, you would not want to swallow the capsule because the germanium would
become arsenic
Of the three sciences, physics, chemistry, and biology, the most complex is
biology because it is based upon both the laws of chemistry and physics.
Which color of light comes from a greater energy transition: red or blue?
blue
What is the name of the following compound? CaCl2
calcium chloride
What is the name of the following compound? CO2
carbon dioxide
Proton:
carries a positive charge and is relatively heavy
Some reactions are more sluggish than others. To speed up these reactions and save energy a(n) ________ is sometimes added.
catalyst
The chlorinated fluorocarbons molecules are acting as a(n) ________ by converting hundreds of thousands of molecules before they are inactivated.
catalyst
Classify the following changes as physical or chemical. Wood burns to ashes; water begins to boil; grass grows; a rock is crushed to powder.
chemical; physical; chemical; physical
Which of the following elements is a halogen?
chlorine (Cl)
What is the environmentally unfriendly component of chlorinated fluorocarbons that ultimately damages ozone?
chlorine atoms
Which of the following elements if in the fourth period?
chromium (Cr)
Many dry cereals are fortified with iron, which is added to the cereal in the form of small iron particles. How might these particles be separated from the cereal?
collect the iron filings with a magnet
If an atom were the size of a baseball, its nucleus would be about the size of a(n)
flea
When you touch a piece of ice with your finger, energy flows
from your finger to the ice
Which of these does not describe a metal at room temperature?
gas
Which of the following material phases cannot form a solution?
gases solids liquids
Which of the following is an example of a chemical change?
gasoline being used in the engine of a car producing exhaust
A catalytic converter increases the amount of carbon dioxide emitted by an automobile. Is this good news or bad news?
good news because it means more noxious chemicals are not being emitted
The sun is spherical due to
gravitation
Elements that are in the same ________ have a tendency to have very similar chemical properties due to periodic trends.
group
Which of the following is not the name of a chemical family?
heavy metals
Helium, He, is a nonmetallic gas and the second element in the periodic table. Rather than being placed adjacent to hydrogen, H, however, helium is placed on the far right of the table because
helium is most similar to other group 18 elements
Heat is thermal energy that flows from
high energy to low energy
How would you classify the following material? swimming pool water
homogeneous mixture
Strontium, Sr (number 38), is especially dangerous to humans because it tends to accumulate in calcium-dependent bone marrow tissues (calcium, Ca, number 20). This fact relates to the organization of the periodic table in that strontium and calcium are both
in group 2 of the periodic table
Two objects move toward each other due to gravity. As the objects get closer and closer, the acceleration of each
increases
A sample of steel is composed of 5 percent carbon and 95 percent iron. Which is the solvent?
iron
What does the following element description actually mean? iron-57
iron with a mass number of 57
Which of the following statements does not describe a proton?
it orbits around the nucleus of an atom
The element silicon has a melting point of 1,410°C and a boiling point of 2,355°C. It is a weak conductor of electricity, its density is 2.3 grams per cubic centimeter and it easily forms silicon dioxide when exposed to air. Which of the following is a chemical property of silicon?
its ability to react with oxygen
Which of the following would not be considered matter?
light
Which of the following elements is an alkali metal?
lithium (Li)
How might you distinguish a sodium-vapor street lamp from a mercury-vapor street lamp?
look at the street lamps through a spectroscope and match their spectral patterns to their respective atomic spectra
How would you describe the volume of the following object? the amount of water in a swimming pool
macroscopic
In a solution of 77 percent nitrogen and 23 percent oxygen, which is the solvent?
nitrogen
In the following reaction sequence for the catalytic formation of ozone from molecular oxygen, which chemical compound is the catalyst: nitrogen monoxide or nitrogen dioxide? O2+2NO→2NO2 2NO2→2NO+2O 2O+2O2→2O3
nitrogen monoxide
Based on atomic size, which would you expect to be more soluble in water: helium, He, or nitrogen, N2?
nitrogen, N2
At absolute zero, a substance has
no more energy to give up
Light is emitted as an electron transitions from a higher energy state to a lower energy state. How long does it take for the actual transition to take place?
no time at all
A sample of iron weighs more after it rusts because
of the additional oxygen it contains.
A TV screen looked at from a distance appears as a smooth continuous flow of images. Up close, however, we see this is an illusion. What really exists are a series of tiny dots (pixels). This is similar to a chemist's view of matter in that
on the submicroscopic level, chemist's find that matter is made of extremely small particles, such as atoms and molecules.
How many electrons are there in the third shell of sodium, Na (atomic number 11)?
one
Which of the following best describes a two-molar sucrose solution?
one liter of solution that contains 2 moles of sucrose
Which of the following solutions is the most dilute?
one liter of water with 1 gram of sugar
Which of the following solutions is the most concentrated?
one liter of water with 10 grams of sugar
Which of the following is said to be quantized?
the number of eggs in an egg carton
What is molarity?
the number of moles of solute per liter of solution
A ball is thrown upwards and caught when it returns. Neglecting air resistance, the speed with which it is caught is
the same as its initial speed
An example of basic research is
the study of the composition of the atom.
The mass number of an element is ________.
the sum of the protons and the neutrons
Which of the following would not be considered a chemical property?
the temperature at which a liquid will boil
Oxygen, O, (number 8), sulfur, S, (number 16), and selenium, Se, (number 34) have such similar chemical properties because
their outermost shells contain the same number of electrons.
Which of the following is not a nonmetal?
titianium (atomic no. =22)
Why is heat often added to chemical reactions performed in the laboratory?
to increase the rate at which reactant collide to allow a greater number of reactants to pass over the activation energy to compensate for the natural tendency of energy to disperse
Does breathing cause you to lose or gain weight?
to lose weight
