Question

1. a chemist needs 0.75 moles of nh₃. what mass should be measured?

17.0 g
8.5 g
22.5 g
12.8 g
clear all

Explanation:

Step1: Calculate molar mass of \( NH_3 \)

Molar mass of \( N \) is \( 14.0 \, g/mol \), molar mass of \( H \) is \( 1.0 \, g/mol \). For \( NH_3 \), molar mass \( M = 14.0 + 3\times1.0 = 17.0 \, g/mol \).

Step2: Use \( m = n\times M \) to find mass

Given \( n = 0.75 \, mol \), \( M = 17.0 \, g/mol \). So \( m = 0.75 \times 17.0 = 12.75 \approx 12.8 \, g \).

Answer:

12.8 g (corresponding to the option with 12.8 g)