Difference between revisions of "Limiting Reactant"

Revision as of 14:33, 23 January 2019

Key Stage 4

Meaning

A limiting reactant is a reactant that is not supplied in a large enough quantity for a complete reaction with the other reactants.

About Limiting Reactants

A limiting reactant prevents a complete reaction.

Examples

2H₂(g) + O₂(g) → 2H₂O(l)

If there is 4g of Hydrogen then 32g of Oxygen is needed for a complete reaction to occur.

If there is 4g of Hydrogen but only 31g of Oxygen then the Oxygen is a limiting reactant.

If there is 3g of Hydrogen but only 32g of Oxygen then the Hydrogen is a limiting reactant.

Finding a Limiting Reactant

Limiting Reactants and Mass
If there are are 6g of Carbon and 15g of Oxygen in the following reaction: C + O₂ → CO₂ Which is the limiting reactant in this reaction?	If there are are 27g of Aluminium and 32g of Oxygen in the following reaction: 4Al + 3O₂ → 2Al₂O₃ Which is the limiting reactant in this reaction?	If there are are 180g of Glucose and 200g of Oxygen in the following reaction: C₆H₁₂O₆ + 6O₂ → 6H₂O + 6CO₂ Which is the limiting reactant in this reaction?
1. Find the Relative Formula Mass of the reactants. M_r of C = 12g M_r of O₂ = 32g	1. Find the Relative Formula Mass of the reactants. M_r of NaOH = 40g M_r of HCl = 36.5g	1. Find the Relative Formula Mass of the reactants. M_r of NaOH = 40g M_r of HCl = 36.5g
2. State the ratio of moles of each chemical needed. 1 moles of C is needed for every 1 mole of O₂	2. State the ratio of moles of each chemical needed. 4 moles of Al are needed for every 3 moles of O₂	2. State the ratio of moles of each chemical needed. 1 mole of C₆H₁₂O₆ is needed for every 6 moles of O₂
3. Find the number of moles supplied of each chemical. No. Moles of C = \(\frac{Mass}{M_r}\) No. Moles of C = \(\frac{6}{12}\) No. Moles = 0.5 mol Therefore 0.5 moles of O₂ is needed. No. Moles of O = \(\frac{Mass}{M_r}\) No. Moles of O = \(\frac{15}{32}\) No. Moles = 0.46 mol Oxygen is the limiting reactant. 1 mole of O₂ = 32g	3. Find the number of moles supplied of each chemical. No. Moles of Al = \(\frac{Mass}{M_r}\) No. Moles of Al = \(\frac{27}{27}\) No. Moles = 1 mol Therefore 0.75 moles of O₂ are needed. No. Moles of O = \(\frac{Mass}{M_r}\) No. Moles of O = \(\frac{32}{32}\) No. Moles = 1 mol Oxygen is the limiting reactant.	3. Find the number of moles supplied of each chemical. No. Moles of C₆H₁₂O₆ = \(\frac{Mass}{M_r}\) No. Moles of C₆H₁₂O₆ = \(\frac{180}{180}\) No. Moles = 1 mol Therefore 6 moles of O₂ are needed. No. Moles of O = \(\frac{Mass}{M_r}\) No. Moles of O = \(\frac{200}{32}\) No. Moles = 6.25 mol Glucose is the limiting reactant.

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-Find the [[Relative Formula Mass]] of the [[reactant]]s.
+'''1. Find the [[Relative Formula Mass]] of the [[reactant]]s.'''
 M<sub>r</sub> of C = 12g
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-Find the [[Relative Formula Mass]] of the [[reactant]]s.
+'''1. Find the [[Relative Formula Mass]] of the [[reactant]]s.'''
 M<sub>r</sub> of NaOH = 40g
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-Find the [[Relative Formula Mass]] of the [[reactant]]s.
+'''1. Find the [[Relative Formula Mass]] of the [[reactant]]s.'''
 M<sub>r</sub> of NaOH = 40g
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-State the [[ratio]] of [[mole]]s of each [[chemical]] needed.
+'''2. State the [[ratio]] of [[mole]]s of each [[chemical]] needed.'''
 [[mole]]s of C is needed for every 1 [[mole]] of O<sub>2</sub>
 | style="height:20px; width:250px; text-align:center;" |
-State the [[ratio]] of [[mole]]s of each [[chemical]] needed.
+'''2. State the [[ratio]] of [[mole]]s of each [[chemical]] needed.'''
 [[mole]]s of Al are needed for every 3 [[mole]]s of O<sub>2</sub>
 | style="height:20px; width:250px; text-align:center;" |
-State the [[ratio]] of [[mole]]s of each [[chemical]] needed.
+'''2. State the [[ratio]] of [[mole]]s of each [[chemical]] needed.'''
 [[mole]] of C<sub>6</sub>H<sub>12</sub>O<sub>6</sub> is needed for every 6 [[mole]]s of O<sub>2</sub>
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-Find the number of [[mole]]s supplied of each [[chemical]].
+'''3. Find the number of [[mole]]s supplied of each [[chemical]].'''
 No. [[Mole]]s of C = <math>\frac{Mass}{M_r}</math>
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 [[mole]] of O<sub>2</sub> = 32g
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-Find the number of [[mole]]s supplied of each [[chemical]].
+'''3. Find the number of [[mole]]s supplied of each [[chemical]].'''
 No. [[Mole]]s of Al = <math>\frac{Mass}{M_r}</math>
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-Find the number of [[mole]]s supplied of each [[chemical]].
+'''3. Find the number of [[mole]]s supplied of each [[chemical]].'''
 No. [[Mole]]s of C<sub>6</sub>H<sub>12</sub>O<sub>6</sub> = <math>\frac{Mass}{M_r}</math>