Question

10. You are given 480 grams of the substance. It's molecular weight is 1440 g. How many
atoms are there in the substance?

Answer 1

Answer:

There are 2.01 × 10²³ atoms in the substance.

General Formulas and Concepts:
Stoichiometry

• Dimensional Analysis
• Molar Ratio
• Avogadro's Number - 6.022 × 10²³ atoms, molecules, formula units, etc.

Explanation:

Step 1: Define

Identify given.

Initial amount of 480 grams of substance.

Molar Weight (Mass) of substance: 1440 g

Step 2: Convert

1. [DA] Set up:
   $\displaystyle 480 \ \text{g} \bigg( \frac{1 \ \text{mol}}{1440 \ \text{g}} \bigg) \bigg( \frac{6.022 \cdot 10^{23} \ \text{atoms}}{1 \ \text{mol}} \bigg)$
2. Evaluate:
   $\displaystyle 480 \ \text{g} \bigg( \frac{1 \ \text{mol}}{1440 \ \text{g}} \bigg) \bigg( \frac{6.022 \cdot 10^{23} \ \text{atoms}}{1 \ \text{mol}} \bigg) = 2.00733 \cdot 10^{23} \ \text{atoms}$
3. Round [Sig Figs]:
   $\displaystyle 2.00733 \cdot 10^{23} \ \text{atoms} \approx \boxed{2.01 \cdot 10^{23} \ \text{atoms}}$

∴ we have converted the given amount of substance into amount of atoms.

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Topic: AP Chemistry

Unit: Stoichiometry