Theoretical Yield Examples in Chemistry

Start with the recap, study the fully worked examples, then use the practice problems to check your understanding of Theoretical Yield.

This page combines explanation, solved examples, and follow-up practice so you can move from recognition to confident problem-solving in Chemistry.

Concept Recap

The maximum amount of product that could be formed in a chemical reaction, calculated from the stoichiometry of the balanced equation using the limiting reactant.

The perfect-world result — the most product you could possibly get if nothing is lost or wasted.

Read the full concept explanation →

How to Use These Examples

  • Read the first worked example with the solution open so the structure is clear.
  • Try the practice problems before revealing each solution.
  • Use the related concepts and background knowledge badges if you feel stuck.

What to Focus On

Core idea: Theoretical Yield starts with the given amount, names the substance, and chooses the conversion factor that cancels the old unit.

Common stuck point: Students often know a formula related to theoretical yield but skip the recognition step: Am I using a mole bridge, molar mass, formula ratio, or balanced-equation ratio to connect measured amounts? That leads to a correct-looking substitution attached to the wrong chemical model.

Sense of Study hint: Ask: Am I using a mole bridge, molar mass, formula ratio, or balanced-equation ratio to connect measured amounts?

Common Mistakes to Watch For

Before you work through the examples, skim the mistake guide so you know which shortcuts and sign errors to avoid.

Stoichiometry Mistakes

Worked Examples

Example 1

easy
Define theoretical yield and explain how it differs from actual yield.

Answer

Theoretical yield = maximum possible product; actual yield≤theoretical yield\text{Theoretical yield = maximum possible product; actual yield} \leq \text{theoretical yield}

First step

1
Theoretical yield is the maximum amount of product that can be formed from a given amount of reactants, assuming the reaction goes to completion with no losses.

Full solution

  1. 2
    It is calculated using stoichiometry from the balanced equation and the limiting reactant.
  2. 3
    Actual yield is the amount of product actually obtained in the laboratory, which is always less than or equal to the theoretical yield due to side reactions, incomplete reactions, and losses during purification.
The theoretical yield represents an ideal scenario. In practice, reactions rarely achieve 100% yield because of practical limitations such as side reactions, equilibrium constraints, and mechanical losses during product isolation.

Example 2

medium
Calculate the theoretical yield of water when 8.08.0 g of hydrogen reacts with excess oxygen. (2H2+O2→2H2O2\text{H}_2 + \text{O}_2 \rightarrow 2\text{H}_2\text{O}; H = 1.0081.008, O = 16.00 g/mol16.00\,\text{g/mol})

Example 3

medium
Compute the theoretical yield of NaCl (in g) when 2 mol Na reacts with 0.5 mol Cl2\text{Cl}_2 via 2Na+Cl2→2NaCl2\text{Na} + \text{Cl}_2 \rightarrow 2\text{NaCl}. (MNaCl=58.5M_{NaCl}=58.5)

Example 4

medium
Determine theoretical yield (g) of NH3\text{NH}_3 when 14 g N2\text{N}_2 (M=28M=28) reacts with 6 g H2\text{H}_2 (M=2M=2). N2+3H2→2NH3N_2 + 3H_2 \rightarrow 2NH_3. (MNH3=17M_{NH_3}=17)

Example 5

hard
From C2H4+H2O→C2H5OH\text{C}_2\text{H}_4 + \text{H}_2\text{O} \rightarrow \text{C}_2\text{H}_5\text{OH}, find the theoretical mass of ethanol from 28 g ethylene (M=28M=28, MC2H5OH=46M_{C_2H_5OH}=46, excess water).

Example 6

challenge
Sodium azide decomposes: 2NaN3→2Na+3N22\text{NaN}_3 \rightarrow 2\text{Na} + 3\text{N}_2. Find the theoretical mass of N2\text{N}_2 from 13.0 g NaN3\text{NaN}_3 (M=65M=65, MN2=28M_{N_2}=28).

Practice Problems

Try these problems on your own first, then open the solution to compare your method.

Example 1

medium
In the reaction 2Na+Cl2→2NaCl2\text{Na} + \text{Cl}_2 \rightarrow 2\text{NaCl}, calculate the theoretical yield of NaCl from 11.511.5 g of sodium with excess chlorine. (Na = 23.023.0, Cl = 35.45 g/mol35.45\,\text{g/mol})

Example 2

hard
A student reacts 6.506.50 g of zinc with 20.020.0 mL of 3.00 M HCl3.00\,\text{M HCl}. The reaction is Zn+2HCl→ZnCl2+H2\text{Zn} + 2\text{HCl} \rightarrow \text{ZnCl}_2 + \text{H}_2. Determine the limiting reactant and the theoretical yield of ZnCl2\text{ZnCl}_2. (Zn = 65.3865.38, ZnCl2\text{ZnCl}_2 = 136.28 g/mol136.28\,\text{g/mol})

Example 3

easy
What is the theoretical yield?

Example 4

easy
In C+O2→CO2C + O_2 \rightarrow CO_2, what is the theoretical yield (mol) of CO2CO_2 from 2 mol C?

Example 5

easy
In 2H2+O2→2H2O2H_2 + O_2 \rightarrow 2H_2O, theoretical yield of H2OH_2O (g) from 2 mol H2H_2? (M=18M=18)

Example 6

easy
Why is the actual yield usually less than the theoretical yield?

Example 7

easy
Which reactant determines the theoretical yield?

Example 8

easy
In N2+3H2→2NH3N_2 + 3H_2 \rightarrow 2NH_3, theoretical yield (mol) of NH3NH_3 from 2 mol N2N_2 (excess H2H_2)?

Example 9

easy
In 2Mg+O2→2MgO2Mg + O_2 \rightarrow 2MgO, theoretical yield (g) of MgO from 1 mol Mg (excess O2O_2)? (MMgO=40M_{MgO}=40)

Example 10

easy
If theoretical yield is 50 g and you recover 50 g, what is the percent yield?

Example 11

medium
In CaCO3→CaO+CO2CaCO_3 \rightarrow CaO + CO_2, theoretical yield (g) of CaOCaO from 100 g CaCO3CaCO_3? (MCaCO3=100M_{CaCO_3}=100, MCaO=56M_{CaO}=56)

Example 12

medium
In 2H2+O2→2H2O2H_2 + O_2 \rightarrow 2H_2O with 4 g H2H_2 (M=2M=2) and excess O2O_2, theoretical yield of water (g)? (M=18M=18)

Example 13

medium
In C+O2→CO2C + O_2 \rightarrow CO_2 with 6 g C (M=12M=12) and 16 g O2O_2 (M=32M=32), theoretical yield of CO2CO_2 (g)? (M=44M=44)

Example 14

medium
In 2Al+3Cl2→2AlCl32Al + 3Cl_2 \rightarrow 2AlCl_3, theoretical yield (mol) of AlCl3AlCl_3 from 4 mol Al (excess Cl2Cl_2)?

Example 15

medium
In N2+3H2→2NH3N_2 + 3H_2 \rightarrow 2NH_3 with 1 mol N2N_2 and 6 mol H2H_2, theoretical yield (mol) of NH3NH_3?

Example 16

medium
Theoretical yield is 80 g and actual yield is 60 g. Percent yield?

Example 17

medium
In 2H2O→2H2+O22H_2O \rightarrow 2H_2 + O_2, theoretical yield (g) of O2O_2 from 36 g water? (MH2O=18M_{H_2O}=18, MO2=32M_{O_2}=32)

Example 18

medium
In Zn+2HCl→ZnCl2+H2Zn + 2HCl \rightarrow ZnCl_2 + H_2, theoretical yield (mol) of H2H_2 from 0.5 mol Zn (excess HCl)?

Example 19

medium
In 2Na+Cl2→2NaCl2Na + Cl_2 \rightarrow 2NaCl, theoretical yield (g) of NaCl from 2 mol Na (excess Cl2Cl_2)? (MNaCl=58.5M_{NaCl}=58.5)

Example 20

challenge
In C+O2→CO2C + O_2 \rightarrow CO_2 with 6 g C (M=12M=12) and 8 g O2O_2 (M=32M=32), find theoretical yield of CO2CO_2 (g). (M=44M=44)

Example 21

challenge
In N2+3H2→2NH3N_2 + 3H_2 \rightarrow 2NH_3 with 14 g N2N_2 (M=28M=28) and 6 g H2H_2 (M=2M=2), theoretical yield of NH3NH_3 (g)? (M=17M=17)

Example 22

challenge
Theoretical yield of a product is 0.5 mol (M=44M=44). If only 17.6 g is recovered, what is the percent yield?

Example 23

easy
In C+O2→CO2\text{C} + \text{O}_2 \rightarrow \text{CO}_2, what is the theoretical yield (mol) of CO2\text{CO}_2 from 5 mol of C (excess O2\text{O}_2)?

Example 24

easy
In 2H2+O2→2H2O2\text{H}_2 + \text{O}_2 \rightarrow 2\text{H}_2\text{O}, theoretical yield (mol) of H2O\text{H}_2\text{O} from 4 mol H2\text{H}_2 (excess O2\text{O}_2)?

Example 25

easy
In Mg+2HCl→MgCl2+H2\text{Mg} + 2\text{HCl} \rightarrow \text{MgCl}_2 + \text{H}_2, theoretical yield (mol) of H2\text{H}_2 from 1.5 mol Mg (excess HCl)?

Example 26

easy
Is theoretical yield ever less than actual yield?

Example 27

easy
In 2KClO3→2KCl+3O22\text{KClO}_3 \rightarrow 2\text{KCl} + 3\text{O}_2, theoretical yield (mol) of O2\text{O}_2 from 2 mol KClO3\text{KClO}_3?

Example 28

easy
In N2+3H2→2NH3\text{N}_2 + 3\text{H}_2 \rightarrow 2\text{NH}_3, theoretical yield (g) of NH3\text{NH}_3 from 1 mol N2\text{N}_2 (excess H2\text{H}_2)? (MNH3=17M_{NH_3}=17)

Example 29

medium
In CaCO3→CaO+CO2\text{CaCO}_3 \rightarrow \text{CaO} + \text{CO}_2, theoretical yield (g) of CO2\text{CO}_2 from 50 g CaCO3\text{CaCO}_3? (MCaCO3=100M_{CaCO_3}=100, MCO2=44M_{CO_2}=44)

Example 30

medium
In 2H2+O2→2H2O2\text{H}_2 + \text{O}_2 \rightarrow 2\text{H}_2\text{O}, theoretical yield (g) of H2O\text{H}_2\text{O} from 16 g O2\text{O}_2 (M=32M=32) with excess H2\text{H}_2? (MH2O=18M_{H_2O}=18)

Example 31

medium
In Fe2O3+3CO→2Fe+3CO2\text{Fe}_2\text{O}_3 + 3\text{CO} \rightarrow 2\text{Fe} + 3\text{CO}_2, theoretical yield (mol) of Fe from 1 mol Fe2O3\text{Fe}_2\text{O}_3 (excess CO)?

Example 32

medium
In Zn+2HCl→ZnCl2+H2\text{Zn} + 2\text{HCl} \rightarrow \text{ZnCl}_2 + \text{H}_2, theoretical yield (g) of H2\text{H}_2 from 6.5 g Zn (M=65M=65, MH2=2M_{H_2}=2, excess HCl)?

Example 33

medium
In 2Al+3CuCl2→2AlCl3+3Cu2\text{Al} + 3\text{CuCl}_2 \rightarrow 2\text{AlCl}_3 + 3\text{Cu}, theoretical yield (mol) of Cu from 0.6 mol Al (excess CuCl2\text{CuCl}_2)?

Example 34

medium
In 2H2+O2→2H2O2\text{H}_2 + \text{O}_2 \rightarrow 2\text{H}_2\text{O}, theoretical yield (g) of H2O\text{H}_2\text{O} from 10 g H2\text{H}_2 (M=2M=2) with excess O2\text{O}_2? (M=18M=18)

Example 35

medium
In C3H8+5O2→3CO2+4H2O\text{C}_3\text{H}_8 + 5\text{O}_2 \rightarrow 3\text{CO}_2 + 4\text{H}_2\text{O}, theoretical yield (mol) of CO2\text{CO}_2 from 2 mol propane (excess O2\text{O}_2)?

Example 36

hard
In 2Al+3Cl2→2AlCl32\text{Al} + 3\text{Cl}_2 \rightarrow 2\text{AlCl}_3, theoretical yield (g) of AlCl3\text{AlCl}_3 from 5.4 g Al (M=27M=27) and 21.3 g Cl2\text{Cl}_2 (M=71M=71)? (MAlCl3=133.5M_{AlCl_3}=133.5)

Example 37

hard
In N2+3H2→2NH3\text{N}_2 + 3\text{H}_2 \rightarrow 2\text{NH}_3, theoretical yield (g) of NH3\text{NH}_3 from 28 g N2\text{N}_2 (M=28M=28) and 9 g H2\text{H}_2 (M=2M=2)? (MNH3=17M_{NH_3}=17)

Example 38

hard
In Mg+2HCl→MgCl2+H2\text{Mg} + 2\text{HCl} \rightarrow \text{MgCl}_2 + \text{H}_2, theoretical yield (g) of H2\text{H}_2 from 4.86 g Mg (M=24.3M=24.3) and 50 mL of 6.0 M HCl? (MH2=2M_{H_2}=2)

Example 39

hard
In Fe2O3+3CO→2Fe+3CO2\text{Fe}_2\text{O}_3 + 3\text{CO} \rightarrow 2\text{Fe} + 3\text{CO}_2, theoretical yield (g) of Fe from 160 g Fe2O3\text{Fe}_2\text{O}_3 (M=160M=160) with excess CO. (MFe=56M_{Fe}=56)

Example 40

hard
In CH4+2O2→CO2+2H2O\text{CH}_4 + 2\text{O}_2 \rightarrow \text{CO}_2 + 2\text{H}_2\text{O}, theoretical yield (g) of CO2\text{CO}_2 from 8 g CH4\text{CH}_4 (M=16M=16, excess O2\text{O}_2)? (MCO2=44M_{CO_2}=44)

Example 41

challenge
In 4NH3+5O2→4NO+6H2O4\text{NH}_3 + 5\text{O}_2 \rightarrow 4\text{NO} + 6\text{H}_2\text{O}, theoretical yield (g) of NO from 17 g NH3\text{NH}_3 (M=17M=17) and 32 g O2\text{O}_2 (M=32M=32)? (MNO=30M_{NO}=30)
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Background Knowledge

These ideas may be useful before you work through the harder examples.

stoichiometrylimiting reactant