Question

How many molecules of carbon dioxide will be formed if 4.98 g of propane is burned in the following reaction?

C3H8+5O2 = 3CO2+4H20

Answer 1

Question: How many molecules of carbon dioxide will be formed if 4.98 g of propane is burned in the following reaction?

$$C_3H_8 + SO_2 = 3CO_2 + 4H_2O$$

Answer: First we must make a proportion

$$C_3H_8 \quad CO_2$$

44 g/mol - 3 mol

4.98 g - X mol, from the following proportion we can calculate amount of substance $CO_2$ $\frac{4.98g C_3 H_8}{44g C_3 H_8} = \frac{X \text{ mol } CO_2}{3 \times 1 \text{ mol } CO_2}$; find out X

$X = \frac{4.98g C_3 H_8 \times 3 \times 1 \text{ mol } CO_2}{44g C_3 H_8} = 0.34 \text{ mol } CO_2$; $X = n_{CO_2}$ - amount of substance $CO_2$;

then find out how many molecules (N) is formed, using Avogadro constant

$$N_A = 6.02214129 \times 10^{23} \text{ mol}^{-1}; N_{CO_2} = n_{CO_2} \cdot N_a;$$

$N = 6.02214129 \times 10^{23} \text{ mol}^{-1} \cdot 0.34 \text{ mol} = 2.05 \times 10^{23}$ molecules of $CO_2$

Final answer: $2.05 \times 10^{23}$ molecules of $CO_2$