Question

CH4 + 202 → CO2 + 2H2O
How many grams of O2 needed to react with 2 moles of CH4?

Answer 1

Answer:

100 g O₂

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

Stoichiometry

• Using Dimensional Analysis

Explanation:

Step 1: Define

[RxN - Balanced]   CH₄ + 2O₂ → CO₂ + 2H₂O

[Given]   2 mol CH₄

[Solve]   x g O₂

Step 2: Identify Conversions

[RxN] 1 mol CH₄ → 2 mol O₂

[PT] Molar Mass of O - 16.00 g/mol

Molar Mass of O₂ - 2(16.00) = 32.00 g/mol

Step 3: Stoichiometry

1. Set up conversion:                     $\displaystyle 2 \ mol \ CH_4(\frac{2 \ mol \ O_2}{1 \ mol \ CH_4})(\frac{32.00 \ g \ O_2}{1 \ mol \ O_2})$
2. Multiply/Divide:                           $\displaystyle 128 \ g \ O_2$

Step 4: Check

Follow sig fig rules and round. We are given 1 sig fig.

128 g O₂ ≈ 100 g O₂

Answer 2

Mass of O₂= 128 g

Further explanation

Given

Reaction

CH₄ + 20₂ → CO₂ + 2H₂O

2 moles of CH₄

Required

Mass of O₂

Solution

In a chemical equation, the reaction coefficient shows the mole ratio of the compounds involved in the reaction, reactants or products

From the equation, mol ratio of CH₄ : O₂ = 1 : 2, so moles O₂ :

= 2/1 x moles CH₄

= 2/1 x 2

= 4 moles

Mass of O₂ :

= mol x MW

= 4 x 32 g/mol

= 128 g