A gas cylinder can hold 1 kg. of H₂ at room temp. & press. :

(i) Find the number of moles of hydrogen present.

(ii) What weight of CO₂ can the cylinder hold under similar conditions to temp. & press.

(iii) If the number of molecules of hydrogen in the cylinder is X, calculate the number of CO₂ molecules in the cylinder under the same conditions of temp. & press.

(iv) State the law that helped you to arrive at the above result.

[H = 1, C = 12, O = 16]

(i) 2 g of hydrogen gas = 1 mole

∴ 1000 g of hydrogen gas = $\dfrac{1000}{2}$ = 500 moles.

(ii) Molar mass of CO₂ = C + 2(O) = 12 + 2(16) = 44 g

1 mole of carbon dioxide = 44 g

∴ 500 moles of carbon dioxide = 44 x 500 = 22,000 g = 22 kg.

Hence, Weight of carbon dioxide in cylinder = 22 kg

(iii) According to Avogadro's law — Equal volumes of all gases under similar conditions of temperature and pressure contain equal number of molecules.

∴ molecules in the cylinder of carbon dioxide = X.

(iv) Avogadro's law — Equal volume of all gases under similar conditions of temperature and pressure contain equal number of molecules.