Chemistry Chapter 6

Which bond is the strongest?

H-F

Which bond is the weakest?

H-I

Which of the following is NOT a reasonable assumption about the chemical reaction whose energy diagram is depicted below?

The activation energy for the reaction is 100kJ.

An equilibrium constant with a value of 8.0 × 106 indicates that at equilibrium _______

the products are favored

An equilibrium constant with a value of 8.0 × 10^6 indicates that at equilibrium ________.

the products are favored

An equilibrium constant with a value of 1.5 × 10-9 indicates that at equilibrium ________.

the reactants are favored

An equilibrium constant with a value of 1.5 × 10^-9 indicates that at equilibrium ________.

the reactants are favored

One step in the metabolism of glucose is depicted below. Which statement best describes how the equilibrium system would respond if the amount of dihydroxyacetone phosphate is decreased?

.The system would shift to the right, producing more dihydroxyacetone phosphate and glyceraldehyde 3-phosphate.

Which of the following energy quantities is equivalent to 578 J?

0.138 kcal

Consider the reaction: C3H8(g) + 5 O2(g) → 3 CO2(g) + 4 H2O(g), where ΔH = -531 kcal/mol. How much heat is released when 3.40 × 1020 molecules of C3H8(g) is burned?

0.300 kcal

Consider the reaction: C3H8(g) + 5 O2(g) → 3 CO2(g) + 4 H2O(g), where ΔH = -531 kcal/mol. How much heat is released when 3.40 × 10^20 molecules of C3H8(g) is burned?

0.300 kcal

Which quantity represents the largest amount of stored energy?

10 grams of fat

Which of the following energy quantities is equivalent to 258 Cal?

1080 kJ

Consider the combustion reaction of propane: C3H8(g) + 5 O2(g) → 3 CO2(g) + 4 H2O(g), where ΔH = -531 kcal. If 6.70 × 104 kcal of energy is released in the reaction, how many grams of oxygen were consumed?

2.02 × 10^4 g of O2

A peanut butter and jelly sandwich contains 9.00 g of fat, 6.00 g of protein, and 25.0 g of carbohydrate. How many Calories does this sandwich provide?

205 Cal

Consider the combustion reaction of propane: C3H8(g) + 5 O2(g) → 3 CO2(g) + 4 H2O(g), where ΔH = -531 kcal. If 1.24 × 105 kcal of energy is released in the reaction, how many moles of propane were burned?

234 mol of C3H8

Consider the reaction, C2H4(g) + H2(g) → C2H6(g), where ΔH = -137 kJ. How many kilojoules are released when 55.3 g of C2H4 reacts?

270. kJ are released

Walking at a brisk pace burns off about 280 Cal/h. How long would you have to walk to burn off the Calories obtained from eating a candy bar that contained 3 g of protein, 12 g of fat, and 28 g of carbohydrates?

50 minutes

Consider the reaction, 3 NO2(g) + H2O(l) → 2 HNO3(aq) + NO(g), where ΔH = -137 kJ. How many kilojoules are released when 92.3 g of NO2 reacts?

91.6 kJ are released

Which of the following is ALWAYS necessary for a chemical reaction to occur between two reactants, A and B?

A and B must collide with the proper orientation and with a certain minimum amount of energy

Which statement about catalysts is NOT true?

A catalyst lowers the ΔH of a chemical reaction.

Which of the following will increase the rate of a reaction?

All of these changes will increase the rate of a reaction.

Which statement concerning the reversible reaction 2 NO2(g) N2O4(g) is true?

As the forward reaction progresses and more N2O4 is formed, the reverse reaction rate increases.

Which value (if any) in each pair corresponds to a faster reaction?

Ea = 1 kcal

Which value (if any) in each pair corresponds to a slower reaction?

Ea = 100 kcal

Which term correctly describes a reaction in which the energy of the products is higher than the energy of the reactants?

Endothermic

A manufacturing company requires 157 kJ of energy to power one of its machines for a day. The reaction shown below would be able to provide a sufficient amount of energy for this purpose.2 HgO(s) → 2 Hg(l) + O2(g) ΔH = 182 kJ

False

A reversible reaction in which K = 9.65 × 10-14 contains a negligible amount of reactants at equilibrium.

False

A reversible reaction in which K = 9.65 × 10^-14 contains a negligible amount of reactants at equilibrium.

False

An endothermic reaction is one in which energy is absorbed and ΔH is negative (-).

False

Chemical reactions are considered favorable if the products have a higher energy than the reactants.

False

Consider the following reversible reaction at equilibrium: C6H12O6 (aq) + 6 O2(g) 6 CO2(g) + 6 H2O(l). If oxygen gas is removed from the reaction vessel, the equilibrium will shift to the right.

False

Consider the following reversible reaction at equilibrium: CO(g) + Cl2(g) COCl2(g). If the pressure inside the reaction vessel is increased, the equilibrium will shift to the left.

False

Consider the reaction: 2 C2H6(g) + 7 O2(g) → 4 CO2(g) + 6 H2O(g). Increasing the concentration of C2H6(g) will decrease the activation energy.

False

Consider the reversible reaction: PCl3(g) + Cl2(g) PCl5(g), where K = 0.5. Since K < 1, [PCl5] must be less than 1 M.

False

In order to cause an endothermic equilibrium reaction to shift in a direction to form more reactants, the reaction must be heated.

False

In the energy diagram shown below, the ΔH of the reaction is labeled by D.

False

Reactions with high Ea are generally fast reactions.

False

The equilibrium constant expression for the reversible reaction: CHCl3(g) + 3 HCl(g) CH4(g) + 3 Cl2(g) is

False

The equilibrium constant expression for the reversible reaction: CHCl3(g) + 3 HCl(g) CH4(g) + 3 Cl2(g) is .

False

The expression for the equilibrium constant, K, for the general reaction: a A + b B c C + d D is

False

The expression for the equilibrium constant, K, for the general reaction: a A + b B c C + d D is .

False

The larger the K for a reaction, the faster the reaction.

False

When the equilibrium constant for a reaction is much less than one (K < 1), the concentration of the products is larger than the concentration of the reactants.

False

Which K value below is consistent with an equilibrium system in which the reactants are favored?

K = 3.7 x 10^-8

Which K value below is consistent with an equilibrium system in which the products are favored?

K = 5.2 x 10^4

A catalytic converter uses a catalyst to catalyze three reactions that clean up the exhaust from an auto engine. Which element is not used as a catalyst in catalytic converters?

Sulfur

Consider the reversible reaction at equilibrium: N2(g) + O2(g) 2 NO(g). What is the effect of removing some N2(g) from the equilibrium system?

The concentration of O2(g) increases

The hydrolysis of sucrose depicted below has K = 1.4 × 105. Which of the following is a reasonable assumption about this reaction once equilibrium is established? sucrose + H2O glucose + fructose

The equilibrium mixture contains mostly glucose and fructose.

The hydrolysis of sucrose depicted below has K = 1.4 × 105. Which of the following is a reasonable assumption about this reaction once equilibrium is established?sucrose + H2O glucose + fructose

The equilibrium mixture contains mostly glucose and fructose.

The hydrolysis of sucrose depicted below has K = 1.4 × 10^5. Which of the following is a reasonable assumption about this reaction once equilibrium is established? sucrose + H2O glucose + fructose

The equilibrium mixture contains mostly glucose and fructose..

The rusting of iron is described by the reaction: 4 Fe(s) + 3 O2(g) → 2 Fe2O3(s). The formation of rust on an exposed piece of iron typically takes several months. Which of the following is NOT a reasonable assumption about this chemical reaction?

The formation of rust has a low activation energy.

The rate of a chemical reaction increases with an increase in the concentration of one or more reactants. This is best explained by which statement?

The higher concentration of reactants increases the frequency of collisions between molecules.

The reversible reaction: PCl3(g) + Cl2(g) PCl5(g), has K = 0.5. Based on the molecular art shown below, what can be inferred about the reaction conditions?A reversible reaction in which K = 9.65 × 10-14 contains a negligible amount of reactants at equilibrium.

The reaction has not yet reached equilibrium.

Activation energy is the minimum amount of energy necessary for a reaction to occur.

True

Ammonia (NH3) is synthesized by the reaction of nitrogen and hydrogen in the presence of an iron catalyst according to the equation below. Removing the iron catalyst would decrease the reaction rate.

True

Bond dissociation energies are always positive numbers.

True

Changes in potential energy occur in chemical reactions.

True

Consider the following reversible reaction at equilibrium: 2 NO(g) + O2(g) 2 NO2(g). If the pressure inside the reaction vessel is increased, the equilibrium will shift to the right.

True

Consider the following reversible reaction at equilibrium: C6H12O6 (aq) + 6 O2(g) 6 CO2(g) + 6 H2O(l). If carbon dioxide gas is removed from the reaction vessel, the equilibrium will shift to the right.

True

Consider the following reversible reaction at equilibrium: CO(g) + Cl2(g) COCl2(g), where ΔH = -108.6 kJ. When the temperature of the reaction vessel decreases, the system responds by forming more COCl2

True

Consider the following reversible reaction at equilibrium: CO(g) + Cl2(g) COCl2(g), where ΔH = -108.6 kJ. When the temperature of the reaction vessel decreases, the system responds by forming more COCl2.

True

Consider the following reversible reaction at equilibrium: CO(g) + Cl2(g) COCl2(g). If chlorine gas is added to the reaction vessel, the concentration of carbon monoxide will decrease.

True

Consider the reaction: 2 C2H6(g) + 7 O2(g) → 4 CO2(g) + 6 H2O(g). Decreasing the concentration of C2H6(g) will decrease the reaction rate.

True

Consider the reversible reaction: CO(g) + Cl2(g) COCl2(g). The reverse reaction is COCl2(g) → CO(g) + Cl2(g)

True

Consider the reversible reaction: CO(g) + Cl2(g) COCl2(g). The reverse reaction is COCl2(g) → CO(g) + Cl2(g).

True

Enzymes are proteins that act as biological catalysts.

True

In order to cause an endothermic equilibrium reaction to shift in a direction to form more products, the reaction must be heated.

True

Increasing the concentration of the reactants in a chemical reaction increases the number of collisions, and the reaction rate increases.

True

Kinetic energy is the energy associated with movement; potential energy is the energy inherent in an object due to its position or composition.

True

Le Châtelier's principle is a general rule used to explain the effect of a change in reaction conditions on equilibrium.

True

The difference in energy between the reactants and the transition state is called the energy of activation, symbolized by Ea.

True

The energy of the reacting molecules affects whether a particular collision will lead to a chemical reaction.

True

The stronger the bond, the higher its bond dissociation energy.

True

When the equilibrium constant for a reversible reaction is much greater than one (K > 1), the equilibrium is said to lie to the right.

True

The law of conservation of energy states that ________.

energy cannot be created or destroyed

For an endothermic reaction at equilibrium, increasing the temperature ________.

increases the rate of the forward reaction to form more products

Catalysts accelerate a reaction by ________.

lowering the energy of activation