Question

Crude calcium carbide, $Ca{C}_2$, is made in an electric furnace by the reaction, $CaO+3C\to Ca{C}_2+CO$
The product contains 64% $Ca{C}_2$ and 36% unreacted $CaO$.
(Given that molecular weight of Ca = 40, C =12, O = 16)

• A. 11500 kg of $CaO$ is to be added to the furnace charge for each 8000 kg of $Ca{C}_2$
• B. 920 kg of $CaO$ is to be added to the furnace charge for each 1000 kg of crude product
• C. 708.2 kg of $CaO$ is to be added to the furnace charge for each 1000 kg of $Ca{C}_2$
• D. 910.3 kg of $CaO$ is to be added to the furnace charge for each 1000 kg of crude product

Answer 1

Answer: (A), (B)

The correct options are
A 11500 kg of $CaO$ is to be added to the furnace charge for each 8000 kg of $Ca{C}_2$
B 920 kg of $CaO$ is to be added to the furnace charge for each 1000 kg of crude product

The reaction is:
$CaO\left(s\right)+3C\left(s\right)\to Ca{C}_2\left(s\right)+CO\left(g\right)$

(A) Final product contains 64% $Ca{C}_2$ & 36% $CaO$
Let mass of product is 100 g
Mass of $Ca{C}_2=64g$
Mass of $CaO=36g$
$\text{Used mole of}CaO=\text{mole of}Ca{C}_{2}produced=\frac{64}{64}$
$\therefore$ mass of $CaO$ for producing $64gCa{C}_2=\frac{64}{64}\times 56=56g$
$\therefore$ Initial total mass of $CaO$ $=56+36=92g$

$64gCa{C}_2$ obtained from = $92gCaO$
$\therefore 1gCa{C}_2$ obtained from $=\frac{92}{64}gCaO$
$8\times {10}^{6}gCa{C}_2$ obtained from = $\frac{92}{64}\times 8\times {10}^6=11500000g$
For 8000 kg $Ca{C}_2\text{requires}=11500kgCaO$.

(B) 100 g product requires $CaO$ = 92 g
1 g product requires = $\frac{92}{100}$
${10}^6$ g product requires = $\frac{92}{100}\times {10}^6$
For 1000 kg (crude) product = 920 kg $CaO$.