Complete Theory

Worked Examples

Example 1Moles, molecules, and mass

Example 2Limiting reagent

Exercise 1Mole and molar massMedium

📋 Problem to solve

How many moles and molecules are contained in

88\,\mathrm{g}

of carbon dioxide (

\mathrm{CO_2}

)? The molar mass is

M = 44\,\mathrm{g/mol}

📌 Given data

m = 88 gM = 44 g/mol

Exercise 2Empirical formulaHard

📋 Problem to solve

An unknown compound contains 40.0% C, 6.7% H, and 53.3% O by mass. Determine its empirical formula.

📌 Given data

C 40.0%H 6.7%O 53.3%

Exercise 3Limiting reagent and yieldHard

📋 Problem to solve

In the reaction

\mathrm{2H_2 + O_2 \to 2H_2O}

4\,\mathrm{g}

of hydrogen react with

40\,\mathrm{g}

of oxygen. What is the theoretical mass of water? (

M(\mathrm{H_2})=2

M(\mathrm{O_2})=32

M(\mathrm{H_2O})=18

g/mol)

📌 Given data

m(H_2)=4 gm(O_2)=40 gM(H_2)=2, M(O_2)=32, M(H_2O)=18 g/mol

📚

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