Question

a reaction requires 2.573 moles of zinc oxide. how many grams of zno are needed?
a. 81.41 g
b. 168.3 g
c. 209.5 g
d. 31.64 g

Explanation:

Step1: Calculate molar mass of ZnO

Molar mass of Zn = 65.38 g/mol, molar mass of O = 16.00 g/mol.
$\text{Molar mass of ZnO} = 65.38 + 16.00 = 81.38\ \text{g/mol}$

Step2: Convert moles to mass

Use formula: $\text{Mass} = \text{Moles} \times \text{Molar Mass}$
$\text{Mass of ZnO} = 2.573\ \text{mol} \times 81.38\ \text{g/mol} \approx 209.5\ \text{g}$

Answer:

C. 209.5 g