Question

How many grams are in 2.3 x 1024 formula units of KNO3?

Answer 1

Answer:

390 g KNO₃

General Formulas and Concepts:

Chemistry

Atomic Structure

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

Math

Pre-Algebra

Order of Operations: BPEMDAS

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

• Left to Right

Explanation:

Step 1: Define

2.3 × 10²⁴ formula units KNO₃

Step 2: Identify Conversions

Avogadro's Number

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

$2.3 \cdot 10^{24} \ formula \ units \ KNO_3(\frac{1 \ mol \ KNO_3}{6.022 \cdot 10^{23} \ formula \ units \ KNO_3} )(\frac{101.11 \ g \ KNO_3}{1 \ mol \ KNO_3} )$ = 386.172 g KNO₃

Step 4: Check

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

386.172 g KNO₃ ≈ 390 g KNO₃