Question

Caluclate the number of grams of oxygen that must react

Answer 1

Answer : The number of grams of oxygen react must be, 170.4 grams.

Solution : Given,

Mass of $C_3H_8$ = 46.85 g

Molar mass of $C_3H_8$ = 44 g/mole

Molar mass of $O_2$ = 32 g/mole

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

$\text{ Moles of }C_3H_8=\frac{\text{ Mass of }C_3H_8}{\text{ Molar mass of }C_3H_8}=\frac{46.85g}{44g/mole}=1.065moles$

Now we have to calculate the moles of $O_2$

The balanced chemical reaction is,

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

From the balanced reaction we conclude that

As, 1 mole of $C_3H_8$ react with 5 mole of $O_2$

So, 1.065 moles of $C_3H_8$ react with $1.065\times 5=5.325$ moles of $O_2$

Now we have to calculate the mass of $O_2$

$\text{ Mass of }O_2=\text{ Moles of }O_2\times \text{ Molar mass of }O_2$

$\text{ Mass of }O_2=(5.325moles)\times (32g/mole)=170.4g$

Therefore, the number of grams of oxygen react must be, 170.4 grams.