Chemistry Final
How many grams of ethanol (MM = 46.08 g/mol) do you need to weigh in order to prepare 500. mL of a 0.15 M solution of ethanol in water?
3.5 grams
How many grams of sucrose, molar mass 342.34 g/mol, are dissolved in water to make 500. mL of a 0.185 M solution?
31.6 grams
The atomic number of carbon is 6. How many valence electrons does each carbon atom have?
4
The atomic number of silicon is 14. How many valence electrons does a silicon atom have?
4
Which of these is an extensive property of a wax candle?
Amount of heat produced by burning the entire candle
Which of these elements is correctly matched up with its number of valence electrons?
Bromine-7
Which chemical equation below correctly shows the conservation of matter?
C5H12 + 8O2 → 5CO2 + 6H2O
Which of the following has a Lewis structures with a double bond?
Carbon Dioxide
Which of the following is an intensive property?
Density
Which change occurs during an endothermic chemical reaction?
Energy is absorbed
Which of the following is a balanced chemical equation?
Fe2O3 + 6 HCl --> 2 FeCl3 + 3 H2O
Which of the these describe a chemical property of a substance?
Flammability of gasoline
At the molecular level, what can occur during a chemical change but not during a physical change?
Formation of covalent bonds
What are the oxidation numbers for the hydrogen and oxygen in H3O+ in the following equation? 2H3O+ + Zn --> H2 + 2H2O + Zn+2
H = +1; O = -2
Which of the following is an example of a chemical change?
Hydrogen and nitrogen form ammonia
Which of the following statements correctly describes the effect of concentration on reaction rate?
Increasing the concentration of reactants increases the reaction rate.
How is the temperature of an ideal gas related to its volume at constant pressure?
Inversely Proportional
What is the chemical formula for potassium sulfide?
K2S
Exothermic reactions result in the release of energy. Which of the following does NOT describe an exothermic reaction?
Melting of ice
What is the source of energy emitted by the Sun?
Nuclear fusion
What is the formula for the compound dinitrogen pentoxide?
N2O5
How does an increase in kinetic energy affect the motion of particles of matter?
Particles move faster as kinetic energy is added
Which is a solid that forms in a solution during a chemical reaction?
Precipitate
Which of the following particles has a positive electrical charge?
Proton
Which particles of an atom are affected by electrical forces?
Protons and electrons only
How can the following equation be balanced? (NH4)2Cr2O7 --> Cr2O3 + N2 + H2O
Put a coefficient of 4 in front of water
Which process would cause a material to change its state from gas to liquid?
Removing energy from the molecules
What are the products of the decomposition of sulfuric acid when it is heated? H2SO4 -->
SO3 + H2O
Which of the following is NOT an example of a chemical change?
Separating a solution of salt-water
Which of the following should be classified as an element?
Silver
Metals are malleable and ductile. What do these properties indicate about the bonds that hold metal atoms together?
The bonding is the same in all directions throughout the metal.
Which statement is true of Bohr's model of the atom?
The electrons travel in definite paths around a small, positively charged nucleus
During an experiment, Monique observed that an oil was not soluble in water. Which of the following is a valid conclusion?
The oil is a nonpolar covalent compound because it does not dissolve in water.
Which of the following is ALWAYS TRUE of two objects that have
The particles that make up the hotter object are moving faster.
How can you determine whether nitrogen dioxide is a compound or a mixture?
The properties of nitrogen dioxide are different from nitrogen and oxygen, so it is a compound.
A scientist carries out a reaction in a test tube. After the bubbling stops, she notices the test tube is very warm. What might she conclude about the reaction?
The reaction was exothermic
What keeps the protons in an atomic nucleus from flying away from one another?
The strong nuclear force overcomes the repulsive force of protons
Why did Thomson's results require a revision of Dalton's atomic theory?
Thomson showed that atoms are not the smallest particles of matter
What occurs during an elastic collision between gas particles?
Total kinetic energy remains the same
Which of these substances is a liquid at room temperature?
Water
The change of state from a liquid to a solid is exothermic. How could this be demonstrated in a lab?
by observing the temperature changes in the surroundings as ice forms
What type of reaction does the equation below describe? 2C4H10 + 13O2 --> 8O2 + 10H2O
combustion
When an electric current passes through water the water can react to form hydrogen and oxygen gases. What type of chemical reaction has occurred?
decomposition
When iron(III) oxide reacts with hydrogen chloride, iron(III) chloride and water are produced. What type of reaction is this?
double replacement
What force is responsible for the stability of all crystals?
electrical attraction
When sodium and chlorine react to form sodium chloride, which one of the following steps involves a release of energy?
formation of a crystal from sodium ions and chlorine ions
Which of the following states is included in an equilibrium expression?
gas aqueous
How could you speed up a chemical reaction?
increase the surface area of the reactants
Potassium iodide has a very high boiling point. What holds the particles of potassium iodide together?
ionic bonds
Which is the measure of the average kinetic energy of particles in an object?
temperature
Which elements often share properties?
those in a group
What is the charge of the nickel ion in nickel nitrate, Ni(NO3)3?
+3
A saturated solution of oxygen in water contains 0.30 grams of oxygen in each liter. What is the molarity of the solution?
.00094 M
How much of a 10.0 gram sample of a radioisotope will remain unchanged after 5 half-lives?
.3125 g
What is the oxidation number for Ca(s)?
0
What are the oxidation numbers of bromine atoms before and after the following reaction? H2 + Br2 --> 2HBr
0 and -1
A 2.80 g piece of metal absorbs 14.0 J of energy as it is heated from 22 to 35 degrees Celsius. Find the specific heat of this metal?
0.385 J/gK
A student weighs 5.0 gram of sodium fluoride, molar mass 42.00 g/mol, and dissolves it in enough water to fill a 250. mL flask. What is the concentration of the solution?
0.48 M
The atomic mass of bromine is 79.904 amu. If a chemist finds that the mass of a sample of bromine gas is 79.90 grams, how many moles of bromine gas are present?
0.5000 mol
What is the density of a cubic block of wood that measures 2.00 centimeters on each side and has a mass of 7.2 grams?
0.90 g/cm3
Mercury(II) oxide can be decomposed to form mercury and oxygen gas. What volume, in liters at STP, is occupied by the gas produced by the decomposition of 0.136 mol of HgO?
1.52L
Molybdenum has a molar mass of 95.94 g/mol. How many moles of molybdenum are present in 150.0 grams of molybdenum?
1.536 mol
A balloon has a volume of 1.5 L at 101 kPa. If the temperature remains constant, what will its volume be at 80.0 kPa?
1.9L
An atom has 5 protons, 5 neutrons and 5 electrons. What is its mass number?
10
What is the percentage by mass of hydrogen in water?
11.1%
How much of a potassium fluoride (MM = 58.10 g/mol) do you need to prepare 100. mL of a 2.00 M KF solution?
11.6 grams
The mass of a mole of sulfur atoms is 32 grams. In a chemical reaction, 2.0 moles of sulfur produces sulfur dioxide gas. What is the mass of the gas produced?
130 grams
The mass of a mole of sulfur atoms is 32.06 grams. In a chemical reaction, 2.0 moles of sulfur produces sulfur dioxide when it reacts with oxygen. What is the mass of the gas produced?
130 grams
An aerosol can contains a gas at 150 kPa. What will the pressure be if the can is heated from 20 to 85 degrees Celsius?
183kPa
Argon is the third period noble gas. What is the electron configuration of argon?
1s22s22p63s23p6
Which of the following equations is NOT balanced?
2 ZnS + 3O2 --> 2 ZnO + SO2
A student measures the volume and mass of an unknown substance in a chemistry lab. The volume is found to be 45.0 mL and the mass was measured to be 97 grams. What is the density of the substance?
2.16 g/mL
Calcium carbonate can be heated to produce calcium oxide, an industrial chemical with a wide variety of uses. The balanced chemical equation for the reaction is: CaCO3(s) --> CaO(s) + CO2(g) How much calcium carbonate must be decomposed to produce 5.00 L of carbon dioxide at STP?
22.3 g
Magnesium has three naturally occurring isotopes: Mg-24 (78.9%), Mg-25 (10.0%), Mg-26 (11.0%). What is the average atomic mass of magnesium?
24.30
Predict the product(s) of the synthesis reaction: 4Al + 3O2 -->
2Al2O3
In finding the average atomic mass of helium, scientists include only two of the element's 6 isotopes, helium-3 and helium-4, in their calculations. The four other isotopes do not naturally occur on earth. The atomic abundance of helium-4 is 0.9999986 and its mass is 4.003 amu. The atomic abundance for helium-3 is 0.0000014 and its mass is 3.016 amu. According to the given information, what is the average atomic mass for helium?
4.002994396 amu
What is the total number of ions produced by dissolving 1.0 mole of aluminum sulfate in water?
5.0 mol
You have a solution of hydrochloric acid labeled "2.00 M HCl". How much of this solution would you measure into a 250 mL flask in order to prepare a solution of HCl at a concentration of 0.40 M?
50. mL
Sodium reacts with chlorine to form sodium chloride according to the following reaction: 2Na + Cl2 --> 2NaCl How many moles of Cl2 react with 100. moles of sodium to form sodium chloride?
50.0 mol
Sodium reacts with chlorine to form sodium chloride. How many moles of chlorine react with 100. moles of sodium to form sodium chloride?
50.0 mol
Using the following balanced equation: 2H2 + O2 --> 2H2O, what is the number of moles of water that can be produced from 12 grams of hydrogen gas?
6.0 mol
How many moles of oxygen gas are there in 135 L of oxygen at STP?
6.02 mol
The molar mass of O2 is 32.0 grams, and the molar mass of magnesium is 24.30 grams. How many grams of oxygen are required to burn 10.0 g of magnesium if the reaction of the two elements creates magnesium oxide?
6.61 grams
Lithium has two isotopes: 92.5% of the atoms are Lithium-7. The remaining atoms are Lithium-6. What is the average atomic mass of Lithium?
6.925
How many electrons can be contained in the second energy level of an atom? Correct Answer:
8
What is the maximum number of valence electrons a neutral atom can have?
8
Which of the following is a true statement regarding catalysts?
A catalyst can increase the rate of a chemical reaction.
Which of these observations would likely be an indication of a chemical change?
A change in odor when two substances are mixed
Which of the following materials should be classified as a mixture?
Air
What is the equilibrium expression for the chemical reaction represented by the equation? PCl3(s) + Cl2(g) <--> PCl5(s)
k = 1/[Cl2]
What is the equilibrium expression represented by the equation? 2HI(g) <--> H2(g) + I2(g)
k = [H2][I2]/[HI]2
What is the equilibrium expression for the chemical reaction represented by this equation? N2 + 3H2 <--> 2NH3
k = [N2][H2]3/[NH3]2
When aluminum is added to lead nitrate, a single replacement reaction occurs. Predict the products of this reaction.
lead and aluminum nitrate
Which of these forces has the least strength?
london dispersion force
What causes an atom to emit light that is detected in its emission spectrum?
movement of an electron to a lower energy level
Which of the following crystals would be MOST LIKELY to have a very low melting point?
nonpolar covalent molecular crystal
What differentiates the three isotopes of hydrogen?
number of neutrons
During a laboratory experiment Juanita observes a model of two bonded atoms. She is told the atoms are both non-metals. Which of the following is a valid conclusion?
she is looking at a model of a covalent bond