chapter 6 hw

Which of the following is a true statement about the energy diagram shown below A) A labels the Ea of the reaction and B labels Δ H of the reaction. B) A labels the Δ H of the reaction and B labels Ea of the reaction. C) C labels the activation energy. D) D labels the reactants and E labels the products.

A) A labels the Ea of the reaction and B labels Δ H of the reaction

Which answer corresponds to the fastest reaction rate? A) Ea = 1 kcal B) Ea = 10 kcal C) Ea = 100 kcal D) Reaction rate is independent of Ea value.

A) Ea = 1 kcal

Which statement concerning ΔH is true? A) The magnitude of ΔH indicates the rate of a reaction. B) The magnitude of ΔH indicates the difference in energy between the reactants and products. C) The magnitude of ΔH represents the energy barrier that must be overcome in order for a reaction to proceed. D) More than one of the answers are true. E) None of the choices are correct.

B) The magnitude of ΔH indicates the difference in energy between the reactants and products

Which term correctly describes a reaction in which the energy of the products is higher than the energy of the reactants?A) oxidation-reduction B) endothermic C) exothermic D) combustion E) double replacement

B) endothermic

Catalysts accelerate a reaction by ________. A) lowering the enthalpy of the reaction B) lowering the energy of activation C) raising the enthalpy of the reaction D) raising the energy of activation E) More than one of the answers are correct.

B) lowering the energy of activation

An equilibrium constant with a value of 8.0 × 106 indicates that at equilibrium ________ A) the reactants are favored B) the products are favored C) approximately equal concentrations of reactants and products are present D) there are more reactants present than products E) None of the choices are correct.

B) the products are favored

Which statement about catalysts is NOT true? A) A catalyst increases the rate of a chemical reaction. B) A catalyst lowers the activation energy of a chemical reaction. C) A catalyst lowers theΔH of a chemical reaction. D) A catalyst is recovered unchanged in the reaction it catalyzes. E) All of the choices are correct.

C) A catalyst lowers the ΔH of a chemical reaction.

Which bond is the strongest?A) H-Br B) H-Cl C) H-F D) H-I E) All bonds involve a hydrogen-halogen bond, so they are all equivalent.

C) H-F

Which K value below is consistent with an equilibrium system in which the reactants are favored? A) K = 1 B) K = 1.8 x 103 C) K = 3.7 x 10-8 D) K = 500 E) K = 0.01

C) K = 3.7 x 10-8

For an exothermic reaction, which of the following changes would result in the formation of additional reactants? A) addition of a catalyst B) increasing the temperature C) adding products D) lowering the activation energy E) None of the choices are correct.

C) adding products

Which of the following is ALWAYS necessary for a chemical reaction to occur between two reactants, A and B? A) Equal amounts of A and B must be present. B) A and B must be present in the same physical state. C) The reaction must be carried out at a temperature higher than room temperature.D) A and B must collide with the proper orientation and with a certain minimum amount of energy.E) The mass of A and B must be equal.

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

Which statement concerning the reversible reaction 2 NO2( g)N2O4( g) is true? A) NO2is the product of the forward reaction.B) The reverse reaction produces N2O4.C) At the start of the reaction, the forward and reverse reaction rates are equal.D) As the forward reaction progresses and more N2O4is formed, the reverse reaction rate increases.E) The concentrations of NO2and N2O4are equal once equilibrium has been achieved.

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

The decomposition of PCl5 is an endothermic process: PCl5(g) PCl3(g) + Cl2(g). Which of the following changes would result in the production of additional Cl2(g)? A) increasing the temperature B) increasing the concentration of PCl3(g) C) decreasing the pressure on the system D) None of these changes will produce additional Cl2. E) All of these changes will produce additional Cl2.

D) None of these changes will produce additional Cl2.

A reversible reaction has reached equilibrium when which condition is established? A) The reverse reaction begins to occur.B) The concentrations of reactants and products become equal.C) All of the reactants have been converted into products.D) The forward and reverse reaction rates become equal.E) The reverse reaction is faster than the forward reaction.

D) The forward and reverse reaction rates become equal.

The law of conservation of energy states that A) the energy of the reactants and products in a chemical reaction are always equal B) all chemical reactions are reversible C) energy can be created, but not destroyed D) energy cannot be created or destroyed

D) energy cannot be created or destroyed

n the reaction: 2 C2H6( g) + 7 O2( g) → 4 CO2( g) + 6 H2O( g), increasing the concentration of C2H6( g) will ________. A) increase the activation energy of the reaction B) decrease the activation energy of the reaction C) decrease the Δ H of the reaction D) increase the reaction rate E) decrease the reaction rate

D) increase the reaction rate

For which of the following reactions would the concentrations of reactants and productsnot change if the pressure of the system were increased? A) N2(g) + 3H2(g)2NH3(g) B) 2SO2(g) + O2(g)2SO3(g) C) 2H2O(g)2H2(g) + O2(g) D) PCl3(g)PCl5(g) + Cl2(g)E) H2(g) + I2(g)2HI(g)

E) H2(g) + I2(g)2HI(g)

When the pressure of a gas phase reaction at equilibrium decreases, in which direction does the equilibrium shift? A) The equilibrium shifts in the direction that increases the number of moles of gas. B) The equilibrium shifts in the direction that decreases the number of moles of gas. C) The equilibrium does not shift. D) The equilibrium shifts always shifts to the right. E) The equilibrium shifts always shifts to the left.

A) The equilibrium shifts in the direction that increases the number of moles of gas.

For an endothermic reaction at equilibrium, increasing the temperature ________. A) does not shift the equilibrium sinceKis a constant B) increases the rate of the reverse reaction to form more reactants C) increases the rate of the forward reaction to form more products D) increases the rate of the reverse reaction to form more products E) increases the rate of the forward reaction to form more reactants

C) increases the rate of the forward reaction to form more products

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? A) The higher concentration of reactants increases the potential energy of the molecules.B) The higher concentration of reactants increases the activation energy of the reaction.C) The higher concentration of reactants increases the temperature of the molecules.D) The higher concentration of reactants increases the frequency of collisions between molecules.E) The higher concentration of reactants increases the pressure on the molecules.

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

Consider the reaction: C3H8( g) + 5 O2( g) → 3 CO2( g) + 4 H2O( g), where Δ H = -531 kcal. Which statement concerning this reaction is true A) Heat is absorbed. B) The bonds formed in the products are stronger than the bonds broken in the reactants. C) The products are higher in energy than the reactants. D) The reaction is endothermic. E) None of the choices are correct.

The bonds formed in the products are stronger than the bonds broken in the reactants.