A gas cylinder contains 12 × 10 24 molecules of oxygen gas. If Avogadro’s number is 6.022 × 10 23 . Calculate the mass of oxygen present in the cylinder.

The number of molecules present in one mole of oxygen molecule = 6 . 023 × 10 23 Therefore, the number of moles present in 12 × 10 24 molecules of oxygen= 12 × 10 24 6 . 023 × 10 23 = 20 moles Mass of one mole of oxygen molecule = 32 g Therefore, the mass of 20 moles of oxygen molecule = 32 × 20 = 640 g .

A gas cylinder contains 12 × 10 24 molecules of oxygen gas. If Avogadro’s number is 6.022 × 10 23 . Calculate the volume of oxygen at S T P present in the cylinder O = 16 .

Number of moles present in 12 × 10 24 molecules of oxygen molecule= 12 × 10 24 6 . 023 × 10 23 = 20 moles. Volume of oxygen gas that occupies 1 mole = 22 . 4 L Therefore, volume of oxygen gas occupied in 20 moles = ( 20 × 22 . 4 ) L = 448 L

Ethane burns in oxygen to form C O 2 and H 2 O according to the equation, 2 C 2 H 6 + 7 O 2 → 4 C O 2 + 6 H 2 O If 1 250 c c of oxygen is burnt with 300 c c of ethane. Calculate the volume of C O 2 formed.

2 C 2 H 6 + 7 O 2 → 4 C O 2 + 6 H 2 O According to the above reaction where ethane burns in the presence of oxygen, 2 volumes of ethane reacts with oxygen to give 4 volumes of carbon dioxide. This means the volume of carbon dioxide formed is two times the volume of ethane. So the volume of carbon dioxide formed from 300 cc of ethane would be two times the amount of ethane = ( 300 × 2 ) cc Therefore, the amount of carbon dioxide formed from 300 cc of ethane is 600 cc .

E M B I B E

All in One - ICSE Chemistry>Chapter 5 - Mole Concept and Stoichiometry>ARCHIVES*(Last 7 Years)>Q 5

MEDIUM

10th ICSE

IMPORTANT

Earn 100

Calculate the percentage of water of crystallisation in ${C u S O}_{4} . 5 H_{2} O (H = 1, O = 16, S = 32, C u = 64)$ .

Important Questions on Mole Concept and Stoichiometry

HARD

10th ICSE

IMPORTANT

All in One - ICSE Chemistry>Chapter 5 - Mole Concept and Stoichiometry>ARCHIVES*(Last 7 Years)>Q 5

A compound of

X

and

Y

has the empirical formula

{XY}_{2}

. Its vapour density is equal to its empirical formula weight. Determine its molecular formula.

HARD

10th ICSE

IMPORTANT

All in One - ICSE Chemistry>Chapter 5 - Mole Concept and Stoichiometry>ARCHIVES*(Last 7 Years)>Q 6

The ratio between the number of molecules in

2 g

of hydrogen and

32 g

of oxygen is

HARD

10th ICSE

IMPORTANT

All in One - ICSE Chemistry>Chapter 5 - Mole Concept and Stoichiometry>ARCHIVES*(Last 7 Years)>Q 7

A gas of mass

32 g

has a volume of

20 L

at

S T P

. Calculate the gram molecular weight of the gas.

HARD

10th ICSE

IMPORTANT

All in One - ICSE Chemistry>Chapter 5 - Mole Concept and Stoichiometry>ARCHIVES*(Last 7 Years)>Q 7

How much calcium oxide is formed when

82 g

of calcium nitrate is heated?
Also, find the volume of nitrogen dioxide evolved.

2 C a {({N O}_{3})}_{2} \to 2 C a O + 4 {N O}_{2} + O_{2}

(C a = 40, N = 14, O = 16)

.

HARD

10th ICSE

IMPORTANT

All in One - ICSE Chemistry>Chapter 5 - Mole Concept and Stoichiometry>ARCHIVES*(Last 7 Years)>Q 8

A gas cylinder contains

12 \times 10^{24}

molecules of oxygen gas. If Avogadro’s number is

6.022 \times 10^{23}

. Calculate
the mass of oxygen present in the cylinder.

MEDIUM

10th ICSE

IMPORTANT

All in One - ICSE Chemistry>Chapter 5 - Mole Concept and Stoichiometry>ARCHIVES*(Last 7 Years)>Q 8

A gas cylinder contains

12 \times 10^{24}

molecules of oxygen gas. If Avogadro’s number is

6.022 \times 10^{23}

. Calculate
the volume of oxygen at

S T P

present in the cylinder

(O = 16)

.

HARD

10th ICSE

IMPORTANT

All in One - ICSE Chemistry>Chapter 5 - Mole Concept and Stoichiometry>ARCHIVES*(Last 7 Years)>Q 8

A gaseous hydrocarbon contains

82.76 %

of carbon. Given that its vapour density is

29

, find its molecular formula.

(C = 12, H = 1)

HARD

10th ICSE

IMPORTANT

All in One - ICSE Chemistry>Chapter 5 - Mole Concept and Stoichiometry>ARCHIVES*(Last 7 Years)>Q 8

The equation, $4 {NH}_{3} + 5 O_{2} \to 4 NO + 6 H_{2} O$ ,

represents the catalytic oxidation of ammonia. If ammonia $100 {cm}^{3}$ is used, calculate the volume of oxygen required to oxidise the ammonia completely.