Chemistry

Chemical Equilibrium and Stoichiometry

135 Questions

Chemical equilibrium and stoichiometry questions cover equilibrium constants, percent yield, and the Haber process. These concepts test your ability to calculate reaction outcomes and purity. Practice these to excel in physical chemistry sections of competitive tests.

Equilibrium constant calculationsStoichiometric yieldHaber processPercent purityHomogenous equilibrium

Chemical Equilibrium and Stoichiometry Questions

Multiple choice

For which of the following reactions is Kp equal to Kc?

  1. H2(g) + I2(g) <------> 2HI(g)

  2. 2C(s) + O2(g) <------> 2CO(g)

  3. N2(g) + 3H2(g) <------> 2NH3(g)

  4. CaCO3(s) <------> CaO(s) + CO2(g)
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The relation between Kp and Kc is given as Kp = Kc(RT)∆ng………………∆ng is the difference between the number of moles of gaseous products and reactants.For this reaction ∆ng is 0. Hence Kp = Kc. Hence this is the correct answer.

Multiple choice

If K1, K2 be the equilibrium constants of two individual reactions and K3 is the equilibrium constant of a reaction obtained by addition of these two reactions, then correct relation between K1, K2 and K3 will be

  1. K3 = K1/K2

  2. K1 = K3/K2

  3. K1 = K2.K3

  4. K2 = K1.K3
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

This option is correct as the given option may be written as K3  =  K1.K2And when two reactions are added to give the third reaction then equilibrium constant of the third reaction is always the product of the equilibrium constant of the individual reactions. 

Multiple choice

Which of the following is an example of homogenous equilibrium?

  1. Ca(OH)2(s) + H2O(aq) ⇌ Ca2+(aq) + 2OH- (aq)

  2. Ag2O(s) + 2HNO3(aq) ⇌ 2AgNO3(aq) + H2O(l)

  3. Fe3+(aq) + SCN-(aq) ⇌ Fe(SCN)2+(aq)

  4. Ni(s) + 4CO(g) ⇌ Ni(CO)4(g)
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

This answer is correct because all the reactants and products are in the aqueous phase hence, represent homogenous equilibria.

Multiple choice

Using the following data 2CH4 (g) + 3O2 (g) → 2CO (g) + 4H2O (g); ΔG° = -1088 kJ CH4 (g) + 2O2 (g) → CO2 (g) + 2H2O (g); ΔG° = -801 kJ Calculate ΔG° for the reaction 2 CO (g) + O2 (g) → 2CO2 (g)

  1. 1028 KJ

  2. -1028 KJ

  3. 514 KJ
    • 514 KJ

  5. -1889 KJ
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

2CH4 (g) + 3O2 (g) → 2CO (g) + 4H2O (g) ΔG° = -1088 kJ  (Eq. 1) CH4 (g) + 2O2 (g) → CO2 (g) + 2H2O (g); ΔG° = -801 kJ     (Eq. 2)

Reversed Eq. 1 2CO (g) + 4H2O (g) →2CH4 (g) + 3O2 (g); ΔG° = -(-1088 kJ) (Eq. 3) 2 x Eq. 2 2CH4 (g) + 4O2 (g) → 2CO2 (g) + 4H2O (g); ΔG° = 2 x (-801 kJ) (Eq. 4) On adding eq. 3 and eq. 4, we get 2CO (g) + O2 (g) → 2CO2 (g); ΔG° = -(-1088 kJ) - 2 x (-801 kJ) = -514 KJ

Multiple choice

The Kp for the formation of ammonia at 250 0C is 1.42x10-5 atm. Find the Kc for this reaction.

  1. 0.057

  2. 0.0057

  3. 0.57

  4. 0.66
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The equation for the above reaction is

N2  + 3H2 -----------------> 2NH3   (Δ n = 2 - (1+3)  = -2)

Kp = 1.42x10-5

T = 273 + 500

     = 773 K

R = 0.0821 L.atm/mol.K

By substituting the values in the following expression, we have

Kc = Kp/ (RT) Δ n

1.42x10-5/ (0.0821 x 773)-2 = 0.057

Multiple choice

Consider the following equilibrium SO2 (g) + ½ O2 (g) ⇌ SO3 (g), $\Delta$H = –23.5 kCal mo1–1 The formation of SO3 is favoured by

  1. compression and decreasing the temperature

  2. compression and increasing the temperature

  3. expansion and increasing the temperature

  4. expansion and decreasing the temperature
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The reaction is exothermic (delta H < 0) and involves a decrease in moles of gas (1.5 moles to 1 mole). According to Le Chatelier's principle, decreasing temperature favors the exothermic direction, and increasing pressure (compression) favors the side with fewer moles of gas.

Multiple choice reactions of acids and bases properties of acids and bases acids, bases and salts acids and bases chemistry

Ist & IInd dissociation const. for oxalic acid is $K _{1}$  and $K _{2}$  which is right statement is : 

  1. $K _{2}$ ,$K _{1}$ are equal
  2. $K _{2}$ is 1000 times greater thean $K _{1}$
  3. $K _{2}$ is $\frac{1}{1000}$ time than $K _{1}$

  4. All correct
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Oxalic acid H2C2O4 is a diprotic acid. The first dissociation (H2C2O4 → HC2O4- + H+) is easier than the second (HC2O4- → C2O4²- + H+) because removing H+ from a negatively charged species (HC2O4-) is harder. K2 is typically 1/1000 of K1.

Multiple choice chemistry chemical reactions of organic compounds uses of alcohols commercially important alcohols - ethanol some commercially important alcohols commercially important alcohols - methanol methanol

Balanced chemical equations for the following:
Monochloro ethane is hydrolysed with aqueous KOH :

  1. $CH _3CH _2Cl + KOH \rightarrow C _2H _5OH + HCl + K _2O$
  2. $CH _3CH _2Cl + KOH \rightarrow C _2H _3OH + KCl + H _2O$
  3. $CH _3CH _2Cl + KOH \rightarrow C _2H _3Cl + KOH + H _2$
  4. $CH _3CH _2Cl + KOH \rightarrow C _2H _5OH + KCl + H _2O$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Reaction:
$CH _3CH _2Cl + KOH \rightarrow  C _2H _5OH + KCl + H _2O$

when alkyl halide is hydrolysed by aq. KOH then corresponding alcohol is formed.

Multiple choice zoology gas exchange and smoking respiration in human beings respiration and associated structures respiration in humans respiratory organs in humans

Complete and balance the following equation $Na _2HPO _4+X\rightarrow Y+NaH _2PO _4$.

  1. $X=NaHCO _3, Y=NaCl$
  2. $X=NaHCO _3, Y=H _2CO _3$
  3. $X=H _2CO _3, Y=NaH _2CO _3$
  4. $X=H _2CO _3, Y=NaHCO _3$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The reaction Na2HPO4 + H2CO3 -> NaHCO3 + NaH2PO4 is a standard buffer reaction where carbonic acid reacts with disodium hydrogen phosphate to form sodium bicarbonate and sodium dihydrogen phosphate.

Multiple choice botany photosynthesis action spectrum and absorption spectrum spectrum of electromagnetic radiation chloroplast and pigments of photosynthesis site of photosynthesis

Amount of $ C{ O} _{ 2 } $ mixed  annually is about 

  1. $70\times 1{ 0 }^{10 } Kg $
  2. $ 70\times 1{ 0 }^{11 } Kg$
  3. $ 70\times 1{ 0 }^{13 } Kg $
  4. $ 70\times 1{ 0 }^{13 } g $
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

David Keeling started measuring the annual CO2 production from an observatory in Hawaii. He found the amount to be $70\times 1 { 0 } ^ { 10 } Kg$.
So, the correct option is '$70\times 1 { 0 } ^ { 10 } Kg$'

Multiple choice urea organic compounds with functional group containing nitrogen

$NH 2COONH _4 \rightleftharpoons $ ____________.

  1. $NH _2CONH _2$, $H _2O$
  2. $NH _2CONH _2$
  3. $NH _2COONH _2$, $NH _2CONH _2$
  4. $NH _2COONH _2$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The basic process, developed in 1922, is also called the Bosch–Meiser urea process after its discoverers. Various commercial urea processes are characterized by the conditions under which urea forms and the way that unconverted reactants are further processed. The process consists of two main equilibrium reactions, with incomplete conversion of the reactants. 

The second is urea conversion: the slower endothermic decomposition of ammonium carbamate into urea and water:

${ H } _{ 2 }N-COON{ H } _{ 4 }⇌{ (N{ H } _{ 2 }) } _{ 2 }CO+{ H } _{ 2 }O$

Multiple choice chemistry chemical equilibrium equilibrium in physical processes introduction to equilibrium chemical equilibrium and acids-bases

${N} _{2}(g)+3{H} _{2}(g)\rightleftharpoons 2{NH} _{3}(g)+heat$
For the reaction above, what is the effect on the equilibrium position when the pressure is decreased?

  1. Increased production of products

  2. Increased production of reactants

  3. Fluctuations in the amounts of reactants and products

  4. No impact on the equilibrium

  5. Cannot be determined
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The given reaction is :-

${ N } _{ 2 }\left( g \right) +3{ H } _{ 2 }\left( g \right) \rightleftharpoons 2{ NH } _{ 3 }\left( g \right) +heat$
In this equilibrium, the forward reaction is accompanied by decrease in total no. of moles of gaseous species. If pressure on the system is decreased, the equilibrium shifts to the direction in which no. of moles increases as per Le Chatelier's principle. So, the backward reaction is favoured and reactants production is increased.