Question

What mass of propane (C3H8) is needed to produce 346 g carbon dioxide in the following reaction? A. 346 g C3H8 B. 1.86 g C3H8 C. 5075 g C3H8 D. 115 g C3H8

Answer 1

The answer to this question 116 g.

Answer 2

Answer : The correct option is, (D) 115 grams

Explanation :

Mass of $CO_2$ = 346 g

Molar mass of $C_3H_8$ = 44 g/mole

Molar mass of $CO_2$ = 44 g/mole

First we have to calculate the moles of $CO_2$.

$\text{Moles of }CO_2=\frac{\text{Mass of }CO_2}{\text{Molar mass of }CO_2}=\frac{346g}{44g/mole}=7.86moles$

Now we have to calculate the moles of $C_3H_8$.

The balanced chemical reaction is,

$C_3H_8+5O_2\rightarrow 3CO_2+4H_2O$

From the balanced reaction we conclude that,

As, 3 mole of $CO_2$ obtained from 1 mole of $C_3H_8$

So, 7.86 moles of $CO_2$ react to give $\frac{1}{3}\times 7.86=2.62$ moles of $C_3H_8$

Now we have to calculate the mass of $C_3H_8$.

$\text{Mass of }C_3H_8=\text{Moles of }C_3H_8\times \text{Molar mass of }C_3H_8$

$\text{Mass of }C_3H_8=(2.62mole)\times (44g/mole)=115.28g=115g$

Therefore, the mass of propane needed are, 115 grams