Question

Consider the reaction between acetylene, c2h2, and oxygen in a welding torch: 2c2h2(g) + 5o2(g) → 4co2(g) + 2h2o(g) if 5.4 moles of acetylene react with sufficient oxygen, how many grams of co2 will be formed?
a. 2.4 × 102 g
b. 9.5 × 102 g
c. 4.8 × 102 g
d. 1.5 × 102 g
e. 0.49 g

Answer 1

Answer : The mass of $CO_2$ formed will be, $4.8\times 10^2g$

Explanation :

The balanced chemical reaction will be:

$2C_2H_2(g)+5O_2(g)\rightarrow 4CO_2(g)+2H_2O(g)$

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

From the reaction, we conclude that

As, 2 mole of $C_2H_2$ react to give 4 mole of $CO_2$

So, 5.4 moles of $C_2H_2$ react to give $\frac{4}{2}\times 5.4=10.8$ moles of $CO_2$

Now we have to calculate the mass of $CO_2$

$\text{ Mass of }CO_2=\text{ Moles of }CO_2\times \text{ Molar mass of }CO_2$

$\text{ Mass of }CO_2=(10.8moles)\times (44g/mole)=475.2g=4.8\times 10^2g$

Therefore, the mass of $CO_2$ formed will be, $4.8\times 10^2g$

Answer 2

                                      2C2H2(g) + 5O2(g) → 4CO2(g) + 2H2O(g)
   from the reaction     2 mol                              4 mol
from the problem      5.4 mol                         10.8 mol

M(CO2) = 12.0 +2*16.0 = 44.0 g/mol
10.8 mol CO2 * 44.0 g CO2/1 mol CO2 = 475.2 g CO2 ≈480 = 4.8 * 10² g
Answer is  C. 4.8*10² g.