Question

What is the mass of 0.5 moles of water (H$_2$O)?

• A. 18g
• B. 9g
• C. 36g
• D. 45g

Hint:

To find the mass of a substance, multiply the number of moles by its molar mass.

Answer 1

The Correct Option is B

The molar mass of water (H$_2$O) is calculated as: \[ \text{Molar mass of H}_2\text{O} = (2 \times 1) + (16) = 18 \, \text{g/mol} \] Now, we calculate the mass of 0.5 moles of water: \[ \text{Mass} = \text{Moles} \times \text{Molar mass} = 0.5 \, \text{mol} \times 18 \, \text{g/mol} = 9 \, \text{g} \] Thus, the mass of 0.5 moles of water is 9 g. So, the correct answer is option (2).