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# Limiting Reagent

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Sections
Empirical Formula
Molecular Formula
Calculating Molar Mass
Mole Concept
Mass Percent
Stoichiometry
Limiting Reagent
Percent Yield

The Limiting Reagent represents the compound that is totally consumed in the reaction.

###### Limiting Reagent & Theoretical Yield

Concept #1: Limiting Reagent

Theoretical Yield is the maximum amount of product a certain chemical reaction can form. It is determined by the limiting reagent.

Concept #2: Limiting Reagent Stoichiometric Chart

Example #1: Chromium (III) oxide reacts with hydrogen sulfide (H2S) gas to form chromium (III) sulfide and water:

Cr2O3 (s) + 3 H2S (g) → Cr2S3 (s) + 3 H2O (l)

What is the mass of chromium (III) sulfide formed when 14.20 g Cr2O3 reacts with 12.80 g H2S?

Practice: Acrylonitrile (C­3H3N) is the starting material for many synthetic carpets and fabrics. It is produced by the following reaction:

2 C3H6 (g) + 2 NH3 (g) + 3 O2 (g)  → 2 C3H3N (g) + 6 H2O (g)

If 12.0 g C3H6, 10.0 g NH­3, and 5.0 g O2 react, what mass of acrylonitrile can be produced, assuming 100% yield?

Practice: The reaction between solid aluminum and iron (III) chloride can generate temperatures reaching 3000 ºC and is used in welding metals.

2 Al + Fe2O3 → Al2O­3 + 2 Fe

If 150 g of Al are reacted with 432 g of Fe­2O3, what is the mass of the excess reactant remaining?