(a) Calculate the number of moles and the number of molecules present in 1.4 g of ethylene gas. What is the volume occupied by the same amount of ethylene?
(b) What is the vapour density of ethylene?

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Solution

(a) The molecular weight of ethylene
= 12+2+12+2 =28g

$M o l e = \frac{g i v e n m a s s}{m o l a r m a s s} = \frac{1.4}{28} = 0.05 m o l e s$

Number of molecules in 1 mole = $6.023 \times 10^{23}$
Therefore,
Number of molecules in 0.05 mole = $6.023 \times 10^{23} \times 0.05 = 0.3 \times 10^{23} 3 \times 10^{22}$ molecules.
Volume of occupied by 1 mole = 22.4l
volume of occupied by 0.05 = 22.4 $\times$ 0.05 = 1.12 litre

(b)

$v a p o u r space d e n c i t y equals fraction numerator m o l e c u l a r space w e i g h t over denominator 2 end fraction equals 28 over 2 equals 14$

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Similar questions

(a) Calculate the number of moles and number of molecules present in 1.4 g of ethylene gas. What is the volume occupied by the same amount of ethylene?
(b) What is the vapour density of ethylene?
(Avogadro's number = 6 × 10²³; Atomic weight of C = 12, H = 1; Molar volume = 22.4 litres at STP)

Calculate the number of moles and the number of molecules present in 1.4 g of ethylene gas. What is the volume occupied by the same amount of ethylene?

(a) (i) What volume of oxygen is required to burn completely $90 d m^{3}$ of butane under similar conditions of temperature and pressure?

$2 C_{4} H_{10} + 13 O_{2} \to 8 C O_{2} + 10 H_{2} O$

(ii) the vapour density of a gas is 8. What would be the volume occupied by 24.0 g of the gas at STP?
(iii) A vessel contains X number of molecules of hydrogen gas at a certain temperature and pressure. How many molecules of nitrogen gas would be present in the same vessel under the same conditions of temperature and pressure?

(b) $O_{2}$ is evolved by heating $K C l O_{3}$ using $M n O_{2}$ as a catalyst.

$2 K C l O_{3} M n O_{2} - --- \to 2 K C l + 3 O_{2}$

(i) Calculate the mass of $K C l O_{3}$ required to produce 6.72 litres of $O_{2}$ at STP.
[atomic masses of $K = 39, C l = 35.5, O = 16]$
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Q. What is the volume occupied by 4 grams of ethylene at

S T P

(in litres)?

What is the vapour density of ethylene?

(Avogadro's number = 6 x 10²³; Atomic weight of C = 12, H = 1; Molar volume = 22.4 litres at STP)

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(a) Calculate the number of moles and the number of molecules present in 1.4 g of ethylene gas. What is the volume occupied by the same amount of ethylene? (b) What is the vapour density of ethylene?

(a) Calculate the number of moles and the number of molecules present in 1.4 g of ethylene gas. What is the volume occupied by the same amount of ethylene?
(b) What is the vapour density of ethylene?