Unit 7 Review

Values for the specific heat of water, as well as the latent heat of fusion and latent heat vaporization for water are given on back of the California CST periodic table.

The specific heat of aluminum is 0.90 J/g·°C. How much energy is required to raise the temperature of 10 grams of aluminum from 10°C to 20°C?
1. 90 joules
2. 0.009 joules
3. 111 joules
4. 100.9 joules
A 100 gram sample of a metal undergoes a temperature change from 20°C to 50° after absorbing 1500 J of heat. What is the specific heat of the metal?
1. 0.5 J/g·°C
2. 2 J/g·°C
3. 4.5 x 10⁶ J/g·°C
4. 0.25 J/g·°C
How many joules of heat energy are required to raise the temperature of 20 grams of water by 50°C?
1. 4180 joules
2. 239.2 joules
3. 0.00418 joules
4. 19.7 joules
What energy change has occured occurred when 500 grams of water cools from 35°C to 25°C?
1. -20 900 joules
2. 20 900 joules
3. -1196 joules
4. 11.96 joules
How many joules are required to vaporize 10 grams of water at its boiling point?
1. 22 600 joules
2. 226 joules
3. 0.0044 joules
4. 2270 joules
How much energy must be removed from 2 grams of water at 0°C to convert the water to ice?
1. 668 joules
2. 167 joules
3. 0.00599 joules
4. 336 joules
What mass of ice at 0°C can be melted by the addition of 1670 joules of heat?
1. 5 grams
2. 0.2 grams
3. 8350 grams
4. 1670 grams
How many grams of water at 100°C can be converted to steam by the addition of 565 joules of heat?
1. 0.25 grams
2. 4 grams
3. 56 500 grams
4. 1 276 900 joules
A 100 gram piece of brass at a temperature of 100°C is dropped into 100 grams of water that has a temperature of 20°C. Which of the following describes what happens next?
1. They come to equilibrium at a temperature above 60°C, because the metal has a higher specific heat than does the water.
2. They come to equilibrium at a temperature above 60°C, because the metal has a lower specific heat than does the water.
3. They come to equilibrium at a temperature below 60°C, because the metal has a higher specific heat than does the water.
4. They come to equilibrium at a temperature below 60°C, because the metal has a lower specific heat than does the water.
When a piece of gold (specific heat 0.13 J/g·°C) and a piece of iron (specific heat 0.46 J/g·°C) each absorb an equal amount of heat
1. the gold will end up with the higher final temperature
2. the iron will end up with the higher final temperature
3. they will end up at the same final temperature
Which of the following phase changes involve the addition (absorption) of heat?
1. condensation
2. vaporization
3. freezing
4. melting
Which of the following phase changes involve the removal (release) of heat?
1. condensation
2. vaporization
3. freezing
4. melting
When you mixed magnesium with hydrochloric acid in the lab, the reaction got warmer. This indicates that
1. the reaction is exothermic, because energy was released
2. the reaction is endothermic, because energy was released
3. the reaction is exothermic, because energy was absorbed
4. the reaction is endothermic, because energy was absorbed
When you mixed baking soda with citric acid in the lab, the reaction got colder. This indicates that
1. the reaction is exothermic, because energy was released
2. the reaction is endothermic, because energy was released
3. the reaction is exothermic, because energy was absorbed
4. the reaction is endothermic, because energy was absorbed
In an exothermic reaction,
1. the energy content of the reactants is greater than the energy content of the products
2. the energy content of the reactants is less than the energy content of the products
3. the energy content of the reactants is the same as the energy content of the products
In an endothermic reaction,
1. the energy content of the reactants is greater than the energy content of the products
2. the energy content of the reactants is less than the energy content of the products
3. the energy content of the reactants is the same as the energy content of the products
In the diagram above, the energy content of the reactants is
1. 80 kilojoules
2. 160 kilojoules
3. 240 kilojoules
In the diagram above, the energy content of the products is
1. 80 kilojoules
2. 160 kilojoules
3. 240 kilojoules
In the diagram above, the activation energy (E_a) would be calculated by doing which of the following?
1. 240 kilojoules - 160 kilojoules = 80 kilojoules
2. 240 kilojoules - 80 kilojoules = 160 kilojoules
3. 80 kilojoules + 160 kilojoules = 240 kilojoules
4. 160 kilojoules - 80 kilojoules = 80 kilojoules
In the diagram above, the heat of reaction (ΔH) would be calculated by doing which of the following?
1. 240 kilojoules - 160 kilojoules = 80 kilojoules
2. 240 kilojoules - 80 kilojoules = 160 kilojoules
3. 240 kilojoules + 160 kilojoules = 240 kilojoules
4. 160 kilojoules - 80 kilojoules = 80 kilojoules
In the diagram above, the energy content of the products
1. is the same as the energy content of the reactants
2. is the greater than the energy content of the reactants
3. is less than the energy content of the reactants
The diagram above depicts a reaction that is
1. endothermic
2. exothermic
3. isothermic
Which of the following will increase the rate of a chemical reaction?
1. An increase in pressure of gases
2. An increase in concentration of reactants
3. An increase in temperature
4. A decrease in surface area of reactants
An increase in temperature increases the rate of a chemical reaction by what means
1. Increasing the concentration of reactants
2. Increasing pressure
3. Decreasing activation energy
4. Increasing collision energy
5. Increasing collision frequency
Catalysts increase the rate of a chemical reaction by what means?
1. Increasing collision energy
2. Increasing the concentration of reactants
3. Lowering activation energy
4. Increasing temperature
For an effective collision to take place, there must be:
1. A sufficiently hard collision
2. A correctly oriented collision
3. A catalyst present
4. No products present
5. High pressure
Which of the following will slow down the rate of a chemical reaction?
1. Addition of a catalyst
2. Decreasing the temperature
3. Increasing the concentration of reactants
4. Increasing the surface area of the reactants
5. Increasing the pressure
At 25 ºC, a certain reaction is able to produce 0.80 moles of product per minute? At what rate might the product be produced at 35 ºC?
1. 0.40 moles per minute
2. 1.6 moles per minute
3. 0.20 moles per minute
4. 0.80 moles per minute
At 25 ºC, a certain reaction is able to produce 0.80 moles of product per minute? At what rate might the product be produced at 15 ºC?
1. 0.40 moles per minute
2. 1.6 moles per minute
3. 1.20 moles per minute
4. 0.80 moles per minute
Given the following reaction:

P₄(s) + 5 O₂(g) → 2 P₂O₅(s)

If the intial rate of the reaction consumes 1 mole of phosphorus, P₄, per second, what is the rate at which oxygen, O₂, is consumed initially?
1. 1 mole per second
2. 2 moles per second
3. 0.2 moles per second
4. 5 moles per second
Given the following reaction:

P₄(s) + 5 O₂(g) → 2 P₂O₅(s)

If the intial rate of the reaction consumes 1 mole of phosphorus, P₄, per second, what is the rate at which diphosphorus pentoxide, P₂O₅, is formed initially?
1. 1 mole per second
2. 2 moles per second
3. 0.2 moles per second
4. 5 moles per second
Given the following reaction:

C₃H₈(g) + 5 O₂(g) → 3 CO₂ + 4 H₂O(g)

If the intial rate of the reaction produces 2 moles of water vapor, H₂O, per second, what is the rate at which carbon dioxide, CO₂, is formed initially?
1. 3 moles per second
2. 2 moles per second
3. 2.67 moles per second
4. 1.5 moles per second
Given the following reaction:

C₃H₈(g) + 5 O₂(g) → 3 CO₂ + 4 H₂O(g)

If the intial rate of the reaction produces 2 moles of water vapor, H₂O, per second, what is the rate at which oxygen, O₂, is consumed initially?
1. 1 mole per second
2. 2 moles per second
3. 8 moles per second
4. 2.5 moles per second
Given the following reaction:

C₃H₈(g) + 5 O₂(g) → 3 CO₂ + 4 H₂O(g)

If the intial rate of the reaction produces 2 moles of water vapor, H₂O, per second, what is the rate at which propane, C₃H₈, is consumed initially?
1. 1 mole per second
2. 2 moles per second
3. 4 moles per second
4. 0.5 moles per second
Given the following reaction:

2 H₂(g) + O₂(g) → 2 H₂O

As this reaction takes place:
1. the quantity of water vapor, H₂O(g), decreases
2. the quantities of hydrogen, H₂, and oxygen, O₂, decrease
3. the quantities of hydrogen, H₂, and oxygen, O₂, increase
4. the quantity of hydrogen, H₂, increases the quantity of oxygen, O₂, decreases
In chemical reactions, electricity, a spark, and sunlight are all ways in which _______________ may be provided.
1. activation energy
2. reactants
3. products
4. catalysts
Given the following reaction:

H₂(g) + Cl₂(g) → 2 HCl

As this reaction takes place:
1. HCl is produced at the same rate that H₂ is consumed
2. H₂ and Cl₂ are consumed at the same rate
3. HCl is produced at the twice the rate that Cl₂ is consumed
4. HCl is produced at the half the rate that Cl₂ is consumed
When extra NH₃ is added to the following system at equilibrium:

3 H₂(g) + N₂(g) ⇌ 2 NH₃(g)
1. In order to restore equilibrium, the reaction shifts right, toward products
2. In order to restore equilibrium, the reaction shifts left, toward reactants
3. No change occurs
When N₂ is removed from the following system at equilibrium:

3 H₂(g) + N₂(g) ⇌ 2 NH₃(g)
1. In order to restore equilibrium, the reaction shifts right, toward products
2. In order to restore equilibrium, the reaction shifts left, toward reactants
3. No change occurs
When H₂ is added to the following system at equilibrium:

3 H₂(g) + N₂(g) ⇌ 2 NH₃(g)
1. In order to restore equilibrium, the reaction shifts right, toward products
2. In order to restore equilibrium, the reaction shifts left, toward reactants
3. No change occurs
When the pressure is increased on the following system at equilibrium:

3 H₂(g) + N₂(g) ⇌ 2 NH₃(g)
1. In order to restore equilibrium, the reaction shifts right, toward products
2. In order to restore equilibrium, the reaction shifts left, toward reactants
3. No change occurs
When the pressure is decreased on the following system at equilibrium:

3 H₂(g) + N₂(g) ⇌ 2 NH₃(g)
1. In order to restore equilibrium, the reaction shifts right, toward products
2. In order to restore equilibrium, the reaction shifts left, toward reactants
3. No change occurs
When the temperature is decreased on the following system at equilibrium:

2 HCl(aq) + Mg(s) ⇌ MgCl₂(aq) + H₂(g) + heat
1. In order to restore equilibrium, the reaction shifts right, toward products
2. In order to restore equilibrium, the reaction shifts left, toward reactants
3. No change occurs
When the temperature is increased on the following system at equilibrium:

2 HCl(aq) + Mg(s) ⇌ MgCl₂(aq) + H₂(g) + heat
1. In order to restore equilibrium, the reaction shifts right, toward products
2. In order to restore equilibrium, the reaction shifts left, toward reactants
3. No change occurs
When the temperature is decreased on the following system at equilibrium:

2 HCl(aq) + Mg(s) ⇌ MgCl₂(aq) + H₂(g) + heat
1. In order to restore equilibrium, the reaction shifts right, toward products
2. In order to restore equilibrium, the reaction shifts left, toward reactants
3. No change occurs
The system depicted here is maintained at a temperature of 30 degrees celsius. If the temperature of the system is doubled, the system will achieve equilibrium by which of the following responses?
1. A higher percentage of the water vapor in the container will condense to liquid.
2. A higher percentage of the water will move into the vapor phase.
3. The temperature of the liquid water will exceed the temperature of the vapor.
4. The temperature of the vapor will exceed the temperature of the liquid water.
When the temperature is increased on a closed system containing water and its vapor at equilibrium:

H₂O(l) + heat ⇌ H₂O(g)
1. In order to restore equilibrium, more liquid water evaporates
2. In order to restore equilibrium, water vapor condenses to form liquid water
3. No change occurs
When the temperature is decreased on a closed system containing water and its vapor at equilibrium:

H₂O(l) + heat ⇌ H₂O(g)
1. In order to restore equilibrium, more liquid water evaporates
2. In order to restore equilibrium, water vapor condenses to form liquid water
3. No change occurs
When the pressure is decreased on a closed system containing water and its vapor at equilibrium:

H₂O(l) + heat ⇌ H₂O(g)
1. In order to restore equilibrium, more liquid water evaporates
2. In order to restore equilibrium, water vapor condenses to form liquid water
3. No change occurs
When the pressure is increased on a closed system containing water and its vapor at equilibrium:

H₂O(l) + heat ⇌ H₂O(g)
1. In order to restore equilibrium, more liquid water evaporates
2. In order to restore equilibrium, water vapor condenses to form liquid water
3. No change occurs
The process of dissolving Na₂SO₄ in water is known to be exothermic:

Na₂SO₄(s) ⇌ 2 Na⁺(aq) + SO₄^2-(aq) + heat

If the temperature of the solution is decreased, Na₂SO₄ becomes:
1. More soluble
2. Less soluble
3. No change in solubility occurs
The process of dissolving Na₂SO₄ in water is known to be exothermic:

Na₂SO₄(s) ⇌ 2 Na⁺(aq) + SO₄^2-(aq) + heat

As the temperature of the solution increases, Na₂SO₄ becomes:
1. More soluble
2. Less soluble
3. No change in solubility occurs
This is the aqueous iron(III) thiocyanate equilibrium:

Fe³⁺(yellow) + SCN^-(colorless) ⇌ [FeSCN]²⁺(dark red)

If aqueous iron(III) chloride is added to the solution at equilibrium:
1. The solution becomes colorless
2. The solution becomes more yellow
3. The solution turns darker red
4. No change in color occurs
This is the aqueous iron(III) thiocyanate equilibrium:

Fe³⁺(yellow) + SCN^-(colorless) ⇌ [FeSCN]²⁺(dark red)

If aqueous potassium thiocyanate is added to the solution at equilibrium:
1. The solution becomes colorless
2. The solution becomes more yellow
3. The solution turns darker red
4. No change in color occurs
A beaker with a mixture of ice and water is maintained at equilibrium:

H₂O(s) + heat ⇌ H₂O(l)

If the temperature of the system is increased:
1. Ice melts to form liquid water (shift to the right)
2. Water freezes to form ice (shift to the left)
3. No change occurs
A beaker with a mixture of ice and water is maintained at equilibrium:

H₂O(s) + heat ⇌ H₂O(l)

If the temperature of the system is decreased:
1. Ice melts to form liquid water (shift to the right)
2. Water freezes to form ice (shift to the left)
3. No change occurs
A precipitation reaction achieves equilibrium:

BaCl₂(aq) + Na₂SO₄(aq) ⇌ 2 NaCl(aq) + BaSO₄(s)

If barium chloride (BaCl₂) is added to the system, which change occurs?
1. The reaction shifts to the right, and more precipitate is produced
2. The reaction shifts to the left, and some precipitate dissolves
3. No change occurs