Question

12. Calculate the no of molecules in:
34g of ammonia molecules, NH3

Answer 1

1.2 × 10²⁴ molecules NH₃

General Formulas and Concepts:

Chemistry

• Reading a Periodic Table
• Avogadro's Number - 6.022 × 10²³ atoms, molecules, formula units, etc.
• Dimensional Analysis

Step-by-step explanation:

Step 1: Define

34 grams NH₃

Step 2: Define conversions

Avogadro's Number

Molar Mass of N - 14.01 g/mol

Molar Mass of H - 1.01 g/mol

Molar Mass of NH₃ - 14.01 + 3(1.01) = 17.04 g/mol

Step 3: Convert

`34 \ g \ NH_3((1 \ mol \ NH_3)/(17.04 \ g \ NH_3) )((6.022 \cdot 10^(23) \ molecules \ NH_3)/(1 \ mol \ NH_3) )` = 1.20157 × 10²⁴ molecules NH₃

Step 4: Check

We are given 2 sig figs. Follow sig fig rules.

1.20157 × 10²⁴ molecules NH₃ ≈ 1.2 × 10²⁴ molecules NH₃