CH4 + 202 → CO2 + 2H2O
How many grams of O2 needed to produce 36 grams of H2O?

64 g O₂

Math

Pre-Algebra

Order of Operations: BPEMDAS

Chemistry

Atomic Structure

Stoichiometry

Step 1: Define

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

[Given]   36 g H₂O

[Solve]   x g O₂

Step 2: Identify Conversions

[RxN] 2 mol O₂ → 2 mol H₂O

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

[PT] Molar Mas of H - 1.01 g/mol

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

Molar Mass of H₂O - 2(1.01) + 16.00 = 18.02 g/mol

Step 3: Stoichiometry

Step 4: Check

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

63.929 g O₂ ≈ 64 g O₂

Mass of O₂ needed = 64 g

Given

Reaction

CH₄ + 2O₂ → CO₂ + 2H₂O

36 grams of H₂O

Required

Mass of O₂ needed

Solution

mol H₂O :

= mass : MW H₂O

= 36 : 18 g/mol

= 2

From the equation, mol ratio of O₂ : H₂O = 2 : 2, so mol O₂=2

Mass O₂ :

= mol x MW O₂

= 2 x 32 g/mol

= 64 g

definition

                    entropy is a measure of the randomness or the extent of disorder of a chemical process.

                      enthalpy is a measure of the heat change of a reaction occurring at a constant pressure.

measurement units:

                        entropy is measured in joule per kelvin (jk⁻¹)   whereas enthalpy is measured in joule per mole (jmol⁻¹)

requirements:

                            entropy has no requirements or limits, and its change is measured by the division between the heat change of the chemical process and the temperature.

                              in contrast, enthalpy can only be related to the heat change of the reaction under standard conditions.