Quiz2:chapter3: chemical equilibrium

(36) The equilibrium of the reaction:

N_2(g) + O_2(g)  ↔      2NO_(g) -  energy

is not affected by ---------------

(a) increasing the temperature.

(b) increasing the concentration of nitrogen gas

(c.) decreasing the pressure.   

(d) removing nitric oxide from the reaction

(35) In the reaction:

2SO_2(g)+O_2(g)  ↔     2SO_3(g) + energy

 the formation of sulphur trioxide increases as …………………

(a) the temperature decreases.

(b) the pressure increases.

(d.) (a), (b) and (c).

(c) SO₃ is removed from the reaction.

(34) Enzymes act as -----.agents in biological and industrial processes.

(a) oxidizing 

(b.) catalytic 

(c) drying 

(d) antiseptic

(33) The catalysts are considered

(a) metallic elements. 

(b) basic oxides.

(c) metallic compounds.

(d.) (a), (b) and (c).

(32) All the following catalyst properties may be affected during the chemical reaction.except

(a) its appearance.

(b) its surface area.

(c) its physical properties.

(d.) its chemical structure.

(31) The catalyst accelerates the chemical reaction because

(a) it increases the distances between the reactants.

(b.) it decreases the activation energy of the reactants.

(c) it affects the equilibrium point.

(d) (a). (b) and (c).

(38) Increasing the pressure in the following equilibrium reaction:

 N_2(g) + O_2(g)  ↔  2NO_(g) – energy

causes the reaction to shift in the direction which -----------

(a) decreases the absorbed heat.  

(b) increases the concentration of nitrogen gas.

(c) decreases the number of produced moles.      

(d.) no correct answer.

(39) The rate of the forward reaction increases by increasing the temperature and decreasing the pressure in the reaction

(a) H_2(g) + I_2(g)   ↔     2HI_(g)          ΔH = +ve

(b)NO_(g)   ↔    ½ O_2(g) + ½ N_2(g)      ΔH = -ve

(c) N₂H4_(g)   ↔  N_2(g) +2H_2(g)   ΔH = -ve

(d.)2NH_3(g)    ↔    N_2(g) +3H_3(g)     ΔH = +ve

(40) The gelatinous layer in photographic films contains ------

(a) sodium chloride.

(c) silver nitrate.

(b.) silver bromide.

(d) potassium iodide.

(51) Consider the following equilibrium system:

2O_2(g) ↔ 3O_2(g)      Kc=36

What is the concentration of O_3(g) when the equilibrium concentration

Of is 5.8 x 10^-2 mol/L ? -----------

(a.) 2.32 x 10^-3 mol/L

(b) 4.54 x 10^-3 mol/L

(c) 3.87 x 10^-3 mol/L.

(d) 8.7 x 10^-3 mol/L.

(50) Consider the following equilibrium system:

N_2(g) + O_(g) + heat  ↔  2NO_(g)

The amount of NO can be increased by

(a) decreasing the amount of O₂

(b.)increasing the temperature of the reaction.

(c) increasing the pressure.

(d) decreasing the amount of N₂

(49) Equal volumes of 1 mol/l solutions of W and X are mixture.

The reaction below rapidly reaches equilibrium?

W_(aq) + X_{(aq) ↔}Y_(aq) +Z_(aq)

At equilibrium, the concentration of Y(aq) is found to be 4 mol/L. What is the value of

Kc for the above reaction?

(a) 0.25

(b) 0.44

(c)4.0

(d.)16

(47) Consider the following system of equilibrium:

H₂O_(V)+CO_(g) ↔  CO₂+H_2(g)

The position of equilibrium shifts to the right as the result of the addition of some extra

H₂O_(V) How will this shift affect the concentrations of the other gases

(a) [CO] increases, [CO₂] decreases and [H₂] decreases.

(b) [CO] increases, [CO₂] increases and [H₂] decreases.

(c) [CO] decreases. [CO₂] decreases and [H₂] increases.

(d.) [CO] decreases. [CO₂] increases and [H₂] increases.

(46) Consider the following equilibrium system:

 CO_(g)+H₂O_(v)                        CO_2(g) +H_2(g)

 Which of the following actions would cause the concentration of H2(g) to decrease?……

 (a) Adding CO_(g)

(b) Adding H₂O_(v)

(c) Removing CO_2(g)

(d.) Removing H₂O_(v)

(45) Consider the following equilibrium system:

N₂H_4(g)+2O_2(g)   ↔2NO_(g) +2H₂O_(g)

Which of the following action can cause the position of equilibrium to shift to the right?

(a.) Adding N₂H_4(g)

(b) Adding H₂O_(g)

(c) Removing N₂H_4(g)   

(d) Removing O_2(g) 

(44) Consider the following reaction:

CO_2(g) + H_2(g)   ↔ CO_(g)  +H₂O_(v)

1 mole of CO₂ and 2 moles of H_2(g)  are placed in a 2L container. At equilibrium the concentration of CO(g) is 0.28 mol/L.

What is the equilibrium concentration of CO_2(g) and the equilibrium constant, Kc for the reaction?

(a.) 0.22 mol/L, and 0.495     

(b) 360 mol/L and 0.0081  

(c) 0.44 mol/L and 2.02

(d) 0.72 mol/L. and 123

(43) Which of the following is incorrect for a system at equilibrium?

(a) The system has a constant mass.

(b) The system acts to oppose disturbances.

(c) The forward and backward reactions proceed at the same rate.

(d.) The reactant and product concentrations vary with time.

(42) Nitrogen dioxide decomposes on heating according to the following equation

2NO_{2(g) ↔} 2NO_(g)+O_2(g)

When 6.80 moles of NO_2(g) were put into a 1.00L container and heated, the equilibrium mixture contained 1.2 moles of O_2(g) What is the equilibrium constar

Kc for the reaction?...........

(a.) 0.357

(b) 0.655

(c) 1.53

(d) 2.80

(41) Phosphorus reacts with chlorine according to the following equation:

     P_4(s)+6Cl_2(g)  ↔  4PCl_3(g)

What is the equilibrium constant, Kc, for the reaction?

(a)4[PCl₃] / [P4][Cl₂]

(b ) 4[PCl₃] / 6[Cl₂]

(c)[PCl₃]⁴ / [P₄][Cl₂]⁶   

(d.) 4[PCl₃]⁴ / [Cl₂]⁶

(52) An equal number of moles of steam and chlorine are placed in a closed container

at 375 K. The following reaction occurs:

 2H₂O_(g)+2Cl_2(g) ↔ 4HCl_(g) +O_2(g)           Kc=5x 10^-4 at 375°K

Which of the following relates [Cl2] and [HCI) at equilibrium?

(a) [Cl₂] <2 [HCI]

(b.) [Cl₂]2>[HCI]₄

(c) [C_l2]=2[HCI]

(d) [Cl₂]²= [HCI]₄

(53) 2SO_2(g)+O_2(g) ↔  2SO_3(g)      Kc= 4.5

In an experiment, a mixture of 4 moles of sulphur dioxide and 1.5 moles of oxygen is allowed to reach equilibrium.

The moles of SO₃ are  -----------------

(a) 5.5 moles.

(b) 4 moles.

(c) 3 moles.

(d.) less than 3 moles.

(54) Consider the following equilibrium system in a closed vessel reaction:

CH₃CHO_(g)  ↔  CH₄ +CO_2(g)         ΔH>0

What would happen if some CH_4(g) is added to the system? -------------

(a) The amounts of all substanses increases, relative to their previous equilibrium amounts.

(b) The value of Kc increases.

(c) The amounts of CH₃CHO_(g) and CO_(g) both increase, relative to their previous

equilibrium amounts.

(d.) The amount of CH3CHO_(g) increases, relative to the previous equilibrium amounts.

(61) For which of the following equilibrium system will the amounts of reactants increase

with an increase in the container volume ?

(a) C_(g) +CO_2(g)  ↔   2CO_(g)

(b) N_2(g) + 3H_{2(g)  ↔}  2NH_3(g)

(c) 2NO_(g) + O_2(g)  ↔ 2NO_2(g)

(d.) Both (b) and (c).

(60) Consider the following equilibrium system:

PCl_3(g)+O_2(g)  ↔ PCl_5(g)

Which of the following statements is/are correct when the volume of the system is decreased?

(a.) The position of equilibrium shifts to the right.

(b) The rate of the backward reaction increases.

(c) The value of Kc  increases.

(d) Both (a) and (b).

(59) Consider the following equilibrium system:

2SO_2(g) + O_2(g)↔ 2SO_3(g)    K=1.2×10⁴

Some of SO_2(g) is added to the equilibrium system.

Which of the following statements are correct?

(a.) The position of equilibrium shifts to the right.

(b) The rate of the forward reaction increases.

(c) The value of Kc increases,

(d) Both (a) and (b).

(58) In the equilibrium system: in presence of   _{ZnO /Cr2O3}

 CO_(g) + 2H_2(g) ↔ CH₃OH_(g)

Which of the following combinations describes the effect of removing the catalyst (ZnO/Cr2O3) from the above system?

(a) Equilibrium yield decreases and reaction rate decreases.

(b.) Equilibrium yield unchanged and reaction rate decreases.

(c) Equilibrium yield and reaction rate are unchanged.

(d) Equilibrium yield decreases and reaction rate unchanged.

(57) Methanol is manufactured by the reaction of carbon monoxide with hydrogen in the presence of a ZnO/Cr₂O₇ catalyst:

CO_(g) +2H_2(g)  ↔ CH₃OH_(g)

Which of the following combinations describes the effect of increasing the pressure

of the system?

(a) Equilibrium yield decreases and reaction rate increases.

(b) Equilibrium yield decreases and reaction rate decreases.

(c.) Equilibrium yield increases and reaction rate increases.

(d) Equilibrium yield increases and reaction rate decreases.

(56) The system below reaches equilibrium in a closed reaction vessel

4HCl_(aq) + MnO_{2(s) ↔} 2Cl₂(g)+2H₂O_(l)+ Mn²⁺_(aq) +2Cl^-_(aq)     ΔH<0

Which of the following actions will increase the mass of Cl_2(g) in the equilibrium mixture?

(a) Adding some MnO₂

(b) Increasing the temperature.

(c) Decreasing the volume of the reaction vessel.

(d.) Adding something that precipitates the Mn²⁺ ions.

(55)* From the following equilibrium constants:

H₂S_{(aq)  ↔} H⁺_(aq) + HS^-_(aq)  Kc=9.5

HS^-_{(aq)  ↔} H⁺_(aq) + S^2-  Kc=1x10^-19                    

What is the equilibrium constant for the following reaction?

S^2-_(aq) +2H⁺_(aq)↔ H₂S_(aq)

(a) 9.5 x 10^-27

(b) 9.75 x 10^-14

(c) 9.5 x 10¹¹

(d.) 1.05 x 10²⁶

(64) Which of the following statements about enzymes are correct?

(a) Enzymes are proteins.

(b) Enzymes increase the rate of biochemical reactions.

(c) Enzymes increase the equilibrium constant of biochemical reactions.

(d.) Both (a) and (b).