Question

How many moles are in 1.42 x 10^25 molecules of NaCl?

Answer 1

Answer:

23.6 mol NaCl

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

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

Stoichiometry

• Reading a Periodic Table

Explanation:

Step 1: Define

1.42 × 10²⁵ molecules NaCl

Step 2: Identify Conversions

Avogadro's Number

Step 3: Convert

1. Set up:                             $\displaystyle 1.42 \cdot 10^{25} \ molecules \ NaCl(\frac{1 \ mol \ NaCl}{6.022 \cdot 10^{23} \ molecules \ NaCl})$
2. Multiply/Divide:                                                                                                   $\displaystyle 23.5802 \ mol \ NaCl$

Step 4: Check

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

23.5802 mol NaCl ≈ 23.6 mol NaCl