Exam
Which of the above reactions would proceed the fastest?
a
Which of the following is a nonmetal?
Carbon
Which of the following is the mostpolar bond?
C-F
How many electrons are in the third noble gas shell (valence shell) of a sodium atom, (atomic number 11)?
One
Combustion reactions are redox reactions.
True
Where is the warmest water in a frozen pond?
at the bottom
If the following graphs are for the same reaction, which one is most likely the one with an added catalyst?
b
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
Which of the above reactions would proceed the fastest?
c
Given that the above energy profiles have the same scale, which of the reactions would require the most energy?
d
Given the following energy profiles, which of the following reactions is endothermic? R= reactants P= products
d
How much energy, in kilojoules, is released or absorbed from the reaction of one mole of nitrogen, N2, with three moles of molecular hydrogen, H2, to form two moles of ammonia, NH3?
+80 kJ/mol
Which of the following reaction energies is the least exothermic (but still an exothermic reaction)?
-125 kj/mole
What is the density of an object with a mass of 5.0 grams and a volume of 15 milliliters?
0.33 g/ml
In the chemical reaction H2SO4 + 2NaOH mc003-1.jpg Na2SO4 + 2H2O, the coefficient of sodium sulfate is _____.
1
Fourteen grams of nitrogen (atomic mass 14 amu) contains ________.
1 mole of nitrogen atoms
What would the concentration of [OH- ] be if the concentration of [H3O+] was 1 × 10-8M? [H3O+]× [OH-] = Kw = 1 × 10-14
1 × 10-6 M
What would the concentration of OH- be if the concentration of H3O+ was 1 × 10-5M? [H3O+]× [OH-] = Kw = 1 × 10-14
1 × 10-9
What coefficients balance the following equation:____ P4(s) + ____ H2(g) ____ PH3(g)
1,6,4
How many neutrons are in an atom of magnesium-25?
13
A distance of 15 kilometers is how many millimeters?
15,000,000 mm
Which has the greatest number of atoms?
16 g of methane, CH4
What is the formula mass (also called molecular weight) of C6H12O6?
180 amu
A major source of chlorine gas, Cl2, is from the electrolysis of brine, which is concentrated salt water, NaCl (aq). Which of the following is the balanced chemical reaction for this electrolysis reaction?
2 NaCl (aq) + 2 H2O 2 NaOH (aq) + Cl2 (g) + 2 H2 (g)
How many electrons are gained or lost in the following half-reaction? 2 Na 2 Na+
2 electrons are lost
How many electrons are gained or lost in the following half-reaction? Zn Zn2+
2 electrons are lost
Question 19 1 / 1 pts How many electrons are gained or lost in the following half-reaction? 2 Na 2 Na+
2 electrons are lost
How many moles of sugar (sucrose) are there in 5 liters of sugar water that has a concentration of 0.5 M?
2.5 moles
Which of the following is an endothermic reaction?
2SnCl2 + 33 kcal mc030-5.jpg Sn + SnCl4
How many moles of H2 bonds are broken if you react nitrogen with hydrogen according to the following reaction? N2 + 3H2 2 NH3
3
In the reaction below, how many molecules of CO2 can be made from 30 molecules of oxygen? C6H12O6 + 6O2 mc012-1.jpg 6H2O + 6CO2
30
How many electrons are gained or lost in the following half-reaction? C C4-
4 electrons are gained
What is the molarity of a 2.5 liter solution containing 10.0 moles of glucose?
4.0 M
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
How many valence electrons does an atom of As have?
5
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
What is the formula mass of sulfur dioxide, SO2?
64 amu
An object with a mass of 7265 grams has a mass of ______ kilograms.
7.265 kg
About how many molecules of aspirin (formula mass aspirin = 180 amu) are there in a 0.250 gram sample?
8.38 x10E20
An element found in another galaxy exists as two isotopes. If 80% of the atoms have an atomic mass of 80.00 amuand the other 20% have an atomic mass of 82.00 amu, what is the approximate atomic massof the element?
80.4 amu (.8 x 80) + (.2 x 82)
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
Describe how a boiling liquid can be used to cool something (i.e., a refrigerator).
A low-boiling liquid absorbs heat energy, dropping the temperature.
Which of the following statements about strong and weak bases is not true?
A weak base will not react with a strong acid
Which of the following statements about strong and weak bases is not true?
A weak base will not react with a strong acid.
Arrange the following images of an aqueous base solution in order of increasing base strength:
A,B,C
Which of the following is not necessarily shown in a chemically balanced equation?
Atomic number
Aluminum ions carry a 3+ charge, and chloride ions carry a 1-charge. What would be the chemical formula for the ionic compound aluminum chloride?
AlCl3
Which of the following has the greatest number of particles?
All are the same
How might the demand for reproducibility in science have the long-term effect of compelling honesty?
All of the above
Which has greater volume: a 10kg block of lead or a 10 kg block of aluminum?
Aluminum
Which of the following statements is untrue about oxidation and reduction processes?
An oxidation can happen without a reduction.
In his work, G.W. Carver discovered over 300 products that could be made from peanuts. This work on his part is an example of ____.
Applied research
Why don't the electrodes of a fuel cell deteriorate the way the electrodes of a battery do?
As long as fuel is supplied, fuel cells don't run down, but car batteries die when the electron-producing chemicals are consumed.
Which alcohol is leastsoluble in water?
CH3CH2CH2CH2OH
Which alcohol is mostsoluble in water?
CH3OH
Which of the following molecules has a lineargeometry or shape?
CO2
A geologist has a rock analyzed in order to determine its composition. This is an example of____.
Basic Research
Increasing the pressure on a gas from 10 t 20 atm will cause its volume to_____.
Be reduced to half of the original volume
Why is the anode of a battery indicated with negative (-) sign?
Because that is where electrons are being generated.
Which of the following is a halogen?
Bromine
Which of the following can be considered an exothermic process?
Burning piece of paper
Which of the following molecules is nonpolar even though it has polar bonds?
CCl4
What would be the best explanation for the fact that most natural water has a pH of about 5.6?
Carbon dioxide reacts with water to form an acid.
An atom loses an electron to another atom. Is this an example of a physical or chemical change?
Chemical change involving the formation of ions
For the following balanced reaction, which of the following is a gas? 2 Na(l) + Cl2(g) 2 NaCl(s)
Cl2
Which of the following is a chemical change?
Combustion of gasoline
Which of the half-reactions below would be complementary and balance the following half-reaction? Zn+2 Zn
Cu Cu2+
A scientific law_____ natural phenomenon and a theory_____ natural phenomenon.
Describes, explains
What is the name of P2Cl5?
Diphosphorus pentachloride
In the balanced redox reaction: 2 Cu(s) + S(s) → Cu2S(s), how many electrons are gained or lost by each copper atom?
Each copper atom loses one (1) electron
The law of conservation of energy states that
Energy cannot be created or destroyed
When class ends and the students leave, this is most like which phase change of matter?
Evaporation
You turn on the lights of your car to see if the battery is dead. This action, on your part, is an example of an______?
Experiment
The equation CH4 + 2O2 tf006-1.jpg CO2 + H2O is balanced.
False
What is the primary difference between a fuel cell and a battery?
Fuel cells do not run down because they can be refueled; batteries run down and need to be recharged.
Which type of radiation from cosmic sources predominates on the inside of high-flying commercial airplanes?
Gamma
Arrange the following in order of increasing ionization energy: {Ge, P, Si}
Ge<Si<P
In one type of fuel cell the following oxidation-reduction reactions are taking place: 2 H2 + O2 2 H2O What is the fuel?
H2
According to the following reaction, which molecule is acting as a base? H30++HSO4-->H2O+H2SO4
HSO4-
The air in your house is an example of a _________.
Hetergeneous mixture because of the dust particles it contains
You go out to the parking lot and you attempt to start your car and it does not start. You suspect that the battery is dead. This suspicion on your part is an example of a scientific______?
Hypothesis
Identify the species that is oxidized and the species that is reduced in the reaction: 2 I- + Cl2 → 2 Cl- + I2
I- is oxidized and Cl2 is reduced.
Ice floats on the surface of liquid water because _____.
Ice is less dense than water
What is the main characteristic of a strong acid?
It is completely dissociated in water.
What is the main characteristic of a strong base?
It is completely dissociated in water.
How does a catalyst increase the rate of a reaction?
It lowers the activation energy.
What is the advantage of using chlorine gas to disinfect drinking water supplies?
It provides residual protection against pathogens.
As a boulder rolls down a hill, its______ energy increases while its____ energy decreases.
Kinetic/potential
The fact that water always flows down hill can best be classified as a scientific______
Law
How are photovoltaic cells different from many other forms of solar energy?
Light is converted directly to electricity.
The longer the wavelength of electromagnetic radiation the ____ the frequency?
Lower
______is the amount of matter in an object, while_____ is the amount of gravitational force experienced by the matter.
Mass/Weight
Which of the following is a metal?
Mercury
Why are ores so valuable?
Metals can be efficiently extracted from them.
Which of the following is a homogenous mixture?
Milk
Why do red blood cells, which contain an aqueous solution of dissolved ions and minerals, burst when placed in fresh water?
More water molecules enter the cell than leave the cell.
To impart a hickory flavor to a roasted turkey, a cook places a pot of water containing hickory chips in an oven with the turkey. Why does the turkey take longer than expected to cook?
Much of the heat from the oven is consumed in changing the phase of the water.
Which of the following is the leastpolar bond?
N-Cl
When nitrogen and fluorine combine to form a molecule, the most likely chemical formula is _____.
NF3
According to the following reaction, which molecule is acting as a base? H20+NH3->OH-+NH4+
NH3
What are the two half reactions that show how many electrons are gained or lost by each species in the reaction: Ni2+(aq) + Mg(s) → Ni(s) + Mg2+(aq)?
Ni2+(aq) + 2 e- → Ni(s) and Mg(s) → Mg2+(aq) + 2 e-
Iron is useful for reducing copper ions to copper metal. Might it also be used to reduce sodium ions to sodium metal?
No, because sodium ions are too difficult to reduce
In the balanced redox reaction: 2 C2H6(g) + 7 O2(g) → 4 CO2(g) + 6 H2O(g), which species is reduced?
O2(g)
An_____ applies to specific case. An_____ is a generalization based on several observations. An_____ gives the reason for the observed properties or events.
Observation Law Theory
Distinguish between a metal and a metal-containing compound.
Only one of these contains ionic bonds.
Arrange the following elements in order of increasing atomic size: {Ge, P, Si}
P<Si<Ge
Scientific thinking began when___.
People became skeptical of their explanations and turned to experimentation
What is the shape or geometry of NH3?
Pyramidal
Which of the following compounds could never act as an acid?
SO4-2
Which of the following is a metalloid?
Silicon
An electron in the outermost shell of which group 1 element experiences the greatest nuclear charge?
Sodium, Na
In which are the molecules moving faster: a swimming pool of boiling water or a cup of boiling water?
The average motion of the molecules in each is the same
What do the brackets in the following equation represent? [H3O+]× [OH-] = Kw
The brackets mean the molarity of the compound inside them.
What is the difference between a compound and a mixture?
The components of a mixture are not chemically bonded together
Since atoms are mostly empty space, why don't objects pass through one another?
The electrons on the atoms repulse the other electrons on other atoms when they get close.
Water coming out of volcanic sea vents at the bottom of the ocean can reach temperatures in excess of 300ºC without boiling. Explain.
The extreme pressure exerted by the miles of ocean water above prevent the formation of any bubbles of water vapor.
How might electrolysis be used to raise the hull of a sunken ship?
The gaseous products of the electrolysis of water could be collected with large bags attached to the hull of the ship. As the bags inflate with the gas they are buoyed upward pulling the ship also upward.
What chemical change occurs when a wax candle burns?
The heated wax molecules combine with oxygen molecules
The ray of light in a neon sign bends when a magnet is held up to it because_____.
The light arises from the flow of electrons within the tube
Why might coating a metal with another metal that is harder to oxidize prevent the first metal from being oxidized?
The metal that is coated is protected from moisture and oxygen so it doesn't react.
Why is carbon dioxide able to be stored more effectively in ocean water vs. fresh water?
The pH of the ocean is pretty high and so the carbon dioxide is trapped in a neutralization reaction.
How might warmer oceans accelerate global warming?
The solubility of CO2 in water decreases as temperatures rise.
Which contains more heat energy: a swimming pool of boiling water or a cup of boiling water?
The swimming pool because it has greater mass of water
All matter is composed of atoms. Atoms are composed of protons, neutrons, and electrons. These statements are part of a scientific _____.
Theory
Atoms of metallic elements can form ionic bonds, but they are not very good at forming covalent bonds. Why?
They have a great tendency to lose electrons.
In redox reactions, metals tend to undergo oxidation.
True
Photosynthesis is the process by which plants use solar energy to convert carbon dioxide and water to glucose.
True
What is the predominant gas found within a bubble of boiling water?
Water vapor
What is the purpose of a salt-bridge?
What is the purpose of a salt-bridge?
Can a glass be filled to above its brim with water without the water spilling over the edge?
Yes, due to the strong powers of the cohesive forces within water
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.
In a battery, the following two oxidation-reduction reactions are taking place: What is undergoing oxidation?
Zn
Which of the following statements describes a basic solution?
[H3O+]< [OH-]
Which of the following statements describes an acidic solution?
[H3O+]> [OH-]
Given that the above energy profiles have the same scale, which of the reactions is the most exothermic?
a
Which of the following items would you use to make an acidic buffer solution?
acetic acid (a weak acid) and sodium acetate
Cutting back on the pollutants that cause acid rain is one solution to the problem of acidified lakes. Suggest another.
add a neutralizing substance such as limestone
During which process is energy absorbed by the water?
all
Which of the following items would you use to make a basic buffer solution?
ammonium hydroxide (a weak base) and ammonium chloride
What is a base?
anything that accepts a hydrogen ion
In a chemical equation the coefficients ________.
appear before the chemical formulas
If the oceans became acidic, they would start to ________.
release more CO2, which would raise the pH
What is the name of CaCl2?
calcium chloride
Carbon dioxide reacts with water to form ________.
carbonic acid
Some reactions are more sluggish than others. To speed up these reactions and save energy a(n) ________ is sometimes added.
catalyst
In the process of treating wastewater, _____ is added to kill pathogens.
chlorine
If the rate at which we produce CO2 were to stop rising, the levels of CO2 in the atmosphere would ________.
continue to rise
As a solution of CO2in water is heated, the solubility of the CO2_____.
decreases
As water begins to freeze at 0ºC, its density _____.
decreases
As water warms from room temperature at 4ºC to 22ºC, its density _____.
decreases
In the following buffer system, what happens to the concentration of the highlighted molecule if you add base (OH-)? HF+NaF+H20=F-+H30++Na+
decreases
Heat is simply another word for
energy that flows from hot to cold
If an atom were the size of a baseball, its nucleus would be about the size of a(n)
flea
During combustion, the oxygen atoms of oxygen molecules ________.
gain a negative charge
What is a reduction?
gain of electrons
When a sulfur (S) atom forms an ion it _____ two electrons and has a charge of _____.
gains/2-
The elements that make the best reducing agents are the ________.
group 1 alkali metals
A hydrogen atom does not form more than one covalent bond because it _____.
has only one electron to share
As water cools from room temperature at 23ºC to 4ºC, its density _____.
increases
As water warms from room temperature at 0ºC to 4ºC, its density _____.
increases
The overall rate at which humans are producing carbon dioxide is ________.
increasing
The "tail"of a soap molecule dissolves into oil or grease due to _____ interactions.
induced dipole-induced dipole
Softened water doesn't rinse soap off your body so well because it _____.
is missing ions that help the soap molecules to dissolve in water
Technology
is the application of science
When a calcium (Ca) atom forms an ion it _____ 2 electrons and has a charge of _____.
loses/2+
The longer the wavelength of electromagnetic radiation the ____ the energy?
lower
Which of the following is a physical change?
melting ice
Iodine, I2, has a higher melting point than fluorine, F2, because its _____.
molecules are larger
In a battery, the following two oxidation-reduction reactions are taking place: Which reaction is taking place at the anode?
rxn A
As temperature above absolute zero, the phase in which atoms and molecules no longer move is_________
none of the above
A stagnant pond smells worse than a babbling brook because _____.
of lack of sufficient oxygen
Half-frozen fruit punch is always sweeter than the same fruit punch completely melted because
only the water freezes while the sugar remains in solution
The hydronium ion, H3O+, is a ________.
polyatomic ion
The hydroxide ion, HO-, is a ________.
polyatomic ion
The presence of antifreeze in your car's radiator _____ the boiling point and _____ the freezing point of the water.
raises, lowers
The solubility of KCl in water is 34 grams per 100 ml at 20ºC. Such a solution is _____?
saturated
In the treatment of drinking water, _____ is added to settle impurities.
slaked time
The phase change from a solid directly to a gas is known as _____.
sublimation
Chemistry is the study of the____.
submicroscopic, microscopic, and macroscopic because most everything around us is made of atoms and molecules
A scientific hypothesis is a
testable explanation
Robert Millikan's Oil Drop Experiment allowed him to determine ____.
the charge of the electron
J.J Thompson's work allowed him to discover ____.
the charge of the mass radio of the electron
Ernest Rutherford's Gold Foil Experiment allowed him to conclude ____.
the existence of atomic nucleus
What is a reduction?
the gain of electrons
A hot tub and a cup of water are both 104 F. While they are the same temperature______.
the hot tub has more heat energy
What is the activation energy?
the minimum amount of energy to break the bonds in reactants
According to the law of conservation of matter, we must have the same number and type of atoms after the chemical change as were present before the chemical change.
true
The solubility of KCl in water is 34 grams per 100 ml at 20ºC. A solution that contains 25 grams of KCl in 100 ml of water at 20ºC is considered to be _____?
unsaturated
It is important to protect water pipes in your home from freezing because _____.
water expands more than the pipe material, which will fracture the pipes if water in them freezes
What is a chemical reaction?
when one or more new compounds are formed by rearranging atoms
At what point will a buffer solution cease to moderate changes in pH?
when the acting buffering component is all neutralized
The oldest known elements are the ones_______.
with atomic symbols that do not match their modern names
