Question

5. Calculate the number of moles of potassium nitrate, KNO3, in a sample with a mass of 85.2 grams.

Answer 1

Answer:

0.843 mol KNO₃

General Formulas and Concepts:

Math

Pre-Algebra

Order of Operations: BPEMDAS

1. Brackets
2. Parenthesis
3. Exponents
4. Multiplication
5. Division
6. Addition
7. Subtraction

• Left to Right

Chemistry

Atomic Structure

• Reading a Periodic Table
• Using Dimensional Analysis

Explanation:

Step 1: Define

85.2 g KNO₃

Step 2: Identify Conversions

Molar Mass of K - 39.10 g/mol

Molar Mass of N - 14.01 g/mol

Molar Mass of O - 16.00 g/mol

Molar Mass of KNO₃ - 39.10 + 14.01 + 3(16.00) = 101.11 g/mol

Step 3: Convert

$\displaystyle 85.2 \ g \ KNO_3(\frac{1 \ mol \ KNO_3}{101.11 \ g \ KNO_3} )$ = 0.842647 mol KNO₃

Step 4: Check

We are given 3 sig figs. Follow sig fig rules and round.

0.842647 mol KNO₃ ≈ 0.843 mol KNO₃