Given 4.20 x 1022 molecules of He gas, what mass of He do you have?

0.279 g He

General Formulas and Concepts:

Math

Pre-Algebra

Order of Operations: BPEMDAS

Brackets Parenthesis Exponents Multiplication Division Addition Subtraction Left to Right

Chemistry

Atomic Structure

Reading a Periodic TableAvogadro's Number - 6.022 × 10²³ atoms, molecules, formula units, etc.

Stoichiometry

Using Dimensional AnalysisExplanation:

Step 1: Define

4.20 × 10²² molecules He

Step 2: Identify Conversions

Avogadro's Number

[PT] Molar Mass of He - 4.00 g/mol

Step 3: Convert

Set up:                              Multiply/Divide:                                                                                              

Step 4: Check

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

0.278997 g He ≈ 0.279 g He

500bc indiais the answer.