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ICSE Class 10 Chemistry Question 15 of 20

Solved 2018 Question Paper ICSE Class 10 Chemistry — Question 15

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Question

Question 6(b)

Ethane burns in oxygen to form CO2 and H2O according to the equation:

2C2H6 + 7O2 ⟶ 4CO2 + 6H2O.

If 1250 cc of oxygen is burnt with 300 cc of ethane.

Calculate:

(i) the volume of CO2 formed.

(ii) the volume of unused O2.

Answer

[By Lussac's law]

2C2H6+7O2⟶4CO2+6H2O2 vol.:7 vol.⟶4 vol.\begin{matrix} 2\text{C}_2\text{H}_6 & + & 7\text{O}_2 &\longrightarrow & 4\text{CO}_2 & + & 6\text{H}_2\text{O} \\ 2\text{ vol.} & : & 7 \text{ vol.} & \longrightarrow & 4\text{ vol.} \end{matrix}

(i) To calculate the volume of CO2 formed :

C2H6:CO22 vol.:4 vol.300 cc:x\begin{matrix}\text{C}_2\text{H}_6 & : & \text{CO}_2 \\ 2 \text{ vol.} & : & 4 \text{ vol.} \\ 300 \text{ cc} & : & \text{x} \end{matrix}

∴

x=42×300=600 ccx = \dfrac{4}{2} \times 300 = 600 \text{ cc}

Hence, volume of carbon dioxide formed = 600 cc

(ii) To calculate the volume of unused O2 :

C2H6:O22 vol.:7 vol.300 cc:x\begin{matrix}\text{C}_2\text{H}_6 & : & \text{O}_2 \\ 2 \text{ vol.} & : & 7 \text{ vol.} \\ 300 \text{ cc} & : & \text{x} \end{matrix}

∴

x=72×300=1050 ccx = \dfrac{7}{2} \times 300 = 1050 \text{ cc}

Unused oxygen = 1250 - 1050 = 200 cc.

Hence, volume of unused oxygen = 200 cc