What weights of P 4 O 6 and P 4 O 10 will be produced by the combustion of 2 g of P 4 in 2 g of O 2 , leaving no P 4 and O 2 ?

Here, O 2 reacts with phosphorous to form P 4 O 6 first. Then, the newly formed P 4 O 6 reacts with the remaining O 2 to form P 4 O 10 . P 4 + 3 O 2 → P 4 O 6 mol of P 4 = 2 124 = 1 62 mol mol of O 2 = 2 32 = 1 16 mol The mole ratio of P 4 : O 2 = 1 : 3 . So, phosphorous is the limiting reagent. mol of P 4 = mol of P 4 O 6 = 1 62 mol Moles of unused O 2 = 1 16 - 3 × 1 62 = 7 496 mol P 4 O 6 + 2 O 2 → P 4 O 10 1 62 mol 7 496 mol The mole ratio of P 4 O 6 : O 2 = 1 : 2 . So, oxygen will be the limiting reagent. mol of P 4 O 10 = mol of O 2 2 P 4 O 6 = 220 gmol - 1 ; P 4 O 10 = 284 g mol - 1 w 284 = 7 2 × 496 So, the mass of P 4 O 10 = 2 . 004 gram Moles of unused P 4 O 6 = 1 62 - 7 2 × 496 = 9 992 mol So, the mass of P 4 O 6 = 9 992 × 220 = 1 . 996 gram .

A mixture containing KClO 3 , KHCO 3 , K 2 CO 3 and KCl was heated, producing CO 2 , O 2 and H 2 O gases according to the following equations: 2 KClO 3 ( s ) → 2 KCl ( s ) + 3 O 2 2 KHCO 3 ( s ) → K 2 O ( s ) + H 2 O ( g ) + 2 CO 2 ( g ) K 2 CO 3 ( s ) → K 2 O ( s ) + CO 2 ( g ) The KCl does not react under the conditions of the reaction. If 100 . 0 g of the mixture produces 1 . 80 g of H 2 O , 13 . 20 g of CO 2 and 4 . 0 g of O 2 , what was the composition of the original mixture?

For 100 gram of such mixture: ( 1 ) 2 KClO 3 ( s ) → 2 KCl ( s ) + 3 O 2 ( 2 ) 2 KHCO 3 ( s ) → K 2 O ( s ) + H 2 O ( g ) + 2 CO 2 ( g ) ( 3 ) K 2 CO 3 ( s ) → K 2 O ( s ) + CO 2 ( g ) KHCO 3 = 100 gmol - 1 ; K 2 CO 3 = 138 gmol - 1 ; KClO 3 = 122 . 5 g mol - 1 Consider the second equation. Here, two moles of KHCO 3 produced one mole of H 2 O . The number of moles of KHCO 3 = 2 × moles of water produced = 2 × 1 . 8 18 = 0 . 2 mol . Weight of KHCO 3 = 0 . 2 × 100 = 20 gram . Now, consider the first equation. Here, two moles of KClO 3 produced three moles of O 2 . The number of moles of KClO 3 = 2 3 × number of moles of O 2 = 2 3 × 4 32 = 0 . 083 mol . Weight of KClO 3 = 0 . 083 × 122 . 5 = 10 . 2 gram . Now, CO 2 is produced in both second and third reaction. Hence, the total carbon dioxide produced will be due to both the reactions. CO 2 produced in the second reaction will be equal to the moles of KHCO 3 consumed. Hence, the mass of CO 2 due to second reaction = 0 . 2 × 44 = 8 . 8 gram . Mass due to the third reaction is 13 . 2 - 8 . 8 = 4 . 4 gram = 4 . 4 44 = 0 . 1 mol . Hence, the number of moles of K 2 CO 3 = 0 . 1 mol Weight of K 2 CO 3 = 0 . 1 × 138 = 13 . 8 gram . Now, the weight of KCl in the mixture is 100 - ( 20 + 10 . 2 + 13 . 8 ) = 56 gram . Weights are calculated above for 100 gram of mixture. Hence, the weight of components is equal to their percentage.

In a gaseous reaction of the type aA + bB → cC + dD , which statement is wrong?

a grams of A combine with b grams of B , to give c grams of C and d grams of D .

a litres of A combine with b litres of B , to give c litres of C and d litres of D .

a moles of A combine with b moles of B , to give c moles of C and d moles of D .

a molecules of A combine with b molecules of B , to give c molecules of C and d molecules of D .

The equation 2 Al s + 3 2 O 2 g → Al 2 O 3 s shows that:

2 moles of Al react with 3 2 moles of O 2 , to produce 1 mole of Al 2 O 3 .

2 moles of Al react with 3 2 moles of O 2 , to produce 7 2 moles of Al 2 O 3 .

2 g of Al react with 3 2 g of O 2 , to produce 1 mole of Al 2 O 3 .

2 g of Al react with 3 2 L of O 2 , to produce 1 mole of Al 2 O 3 .

MEDIUM

JEE Main

IMPORTANT

Earn 100

Carnallite is a double chloride of potassium and magnesium, containing $38.86 %$ of water. $0.458 g$ of carnalite gave $0.71 g$ of $AgCl$ and $0.666 g$ of carnalite gave $0.27 g$ of ${Mg}_{2} P_{2} O_{7}$ . Find the percentage of $KCl$ in carnalite.

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Important Questions on Problems Based on Equations: Stoichiometry

MEDIUM

JEE Main

IMPORTANT

Modern Approach to Chemical Calculations>Chapter 2 - Problems Based on Equations: Stoichiometry>PROBLEMS>Q 29

What volume(in L) of hydrogen at

NTP

is needed to reduce

125 g

{MoO}_{3}

to its metal? Give an answer to the nearest integer value.

MEDIUM

JEE Main

IMPORTANT

Modern Approach to Chemical Calculations>Chapter 2 - Problems Based on Equations: Stoichiometry>PROBLEMS>Q 30

How much gas (in litres) will be produced at $0 ° C$ and $760 mm$ of pressure, when $10 g$ of oxalic acid is heated with concentrated sulphuric acid? Give an answer to the nearest integer value.

MEDIUM

JEE Main

IMPORTANT

Modern Approach to Chemical Calculations>Chapter 2 - Problems Based on Equations: Stoichiometry>PROBLEMS>Q 31

A natural gas sample contains

84 %

(by volume) of

{CH}_{4}, 10 %

C_{2} H_{6}, 3 %

C_{3} H_{8}

and

3 %

N_{2}

. If a series of catalytic reactions could be used for converting all the carbon atoms of the gas into butadiene,

C_{4} H_{6},

with

100 %

efficiency, how much butadiene could be prepared from

100 g

of the natural gas?

HARD

JEE Main

IMPORTANT

Modern Approach to Chemical Calculations>Chapter 2 - Problems Based on Equations: Stoichiometry>PROBLEMS>Q 32

What weights of

P_{4} O_{6}

and

P_{4} O_{10}

will be produced by the combustion of

2 g

P_{4}

2 g

O_{2}

, leaving no

P_{4}

and

O_{2}

MEDIUM

JEE Main

IMPORTANT

Modern Approach to Chemical Calculations>Chapter 2 - Problems Based on Equations: Stoichiometry>PROBLEMS>Q 33

From the following reactions, $2 {CoF}_{2} + F_{2} \to 2 {CoF}_{3}$ , ${({CH}_{2})}_{n} + 4 {nCoF}_{3} \to {({CF}_{2})}_{n} + 2 nHF + 4 {nCoF}_{2}$ , calculate how much $F_{2}$ will be consumed to produce $1 kg$ of ${({CF}_{2})}_{n}$ .

Give the answer in kg.

HARD

JEE Main

IMPORTANT

Modern Approach to Chemical Calculations>Chapter 2 - Problems Based on Equations: Stoichiometry>PROBLEMS>Q 34

A mixture containing ${KClO}_{3}, {KHCO}_{3}, K_{2} {CO}_{3}$ and $KCl$ was heated, producing ${CO}_{2}, O_{2}$ and $H_{2} O$ gases according to the following equations:

$2 {KClO}_{3} (s) \to 2 KCl (s) + 3 O_{2} 2 {KHCO}_{3} (s) \to K_{2} O (s) + H_{2} O (g) + 2 {CO}_{2} (g) K_{2} {CO}_{3} (s) \to K_{2} O (s) + {CO}_{2} (g)$

The

KCl

does not react under the conditions of the reaction. If

100.0 g

of the mixture produces

1.80 g

H_{2} O, 13.20 g

{CO}_{2}

and

4.0 g

O_{2}

, what was the composition of the original mixture?

EASY

JEE Main

IMPORTANT

Modern Approach to Chemical Calculations>Chapter 2 - Problems Based on Equations: Stoichiometry>Objective Problems>Q 1

In a gaseous reaction of the type $aA + bB \to cC + dD$ , which statement is wrong?

EASY

JEE Main

IMPORTANT

Modern Approach to Chemical Calculations>Chapter 2 - Problems Based on Equations: Stoichiometry>Objective Problems>Q 2

The equation

2 Al (s) + \frac{3}{2} O_{2} (g) \to {Al}_{2} O_{3} (s)

shows that:

Carnallite is a double chloride of potassium and magnesium, containing 38.86% of water. 0.458 g of carnalite gave 0.71 g of AgCl and 0.666 g of carnalite gave 0.27 g of Mg2P2O7. Find the percentage of KCl in carnalite.

Important Questions on Problems Based on Equations: Stoichiometry

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Carnallite is a double chloride of potassium and magnesium, containing $38.86 %$ of water. $0.458 g$ of carnalite gave $0.71 g$ of $AgCl$ and $0.666 g$ of carnalite gave $0.27 g$ of ${Mg}_{2} P_{2} O_{7}$ . Find the percentage of $KCl$ in carnalite.