Stoichiometry, Reaction Types, and Yield Calculations

Stoichiometry, Yields and Reaction Types

Solution

Solution — This is obtained when one chemical becomes completely dissolved in another.

Theoretical Yield

Theoretical yield — If a chemist calculates the maximum amount of product that could be obtained in a chemical reaction, he or she is calculating the theoretical yield.

Stoichiometry

Stoichiometry — Terms used to designate the calculations of quantities of substances involved in chemical reactions.

Percent Yield

Percent yield — This is obtained by dividing the actual yield by the theoretical yield and multiplying by 100%.

Limiting Reactant

Limiting reactant — The reactant that is fully consumed during the reaction.

Practice Questions

1.1 — In the equation 6 CO₂ + 6 H₂O ... the mole ratio of water to oxygen is ...

3.2 — In the equation Al₂(SO₄)₃ + 3 Ca(OH)₂ ... hydroxide to aluminium hydroxide is ...

Unit

UNIT

Reaction Types and Example Equations

• Decomposition reaction — 2 Ag₂O → 4 Ag + O₂
• Double displacement reaction — BaCl₂ + K₂CrO₄ → BaCrO₄ + 2 KCl
• Single displacement reaction — Ag + NaCl → AgCl + Na
• Combination reaction — NH₃ + HCl → NH₄Cl
• Decomposition reaction — 2 H₂O → 2 H₂ + O₂

Balancing

Balance:

- 3 H₃ + ___ N₂ → 2 NH₃

      A           B            C

- 2 AlBr₃ + -3 K... → -6 KBr + Al...

          A              B             C       D

Tabla

TABLA

Worked Example 1

2 Fe + O₂ → 2 FeO

Respuesta del problema:

8 mol Fe × (2 mol FeO / 2 mol Fe) × (71.85 g / 1 mol FeO) = 574.8 g FeO

Worked Example 2

2 C₂H₁₂O + 17 O₂ → 12 CO₂ + 2 O ...

Respuesta del problema:

23.7 mol CO₂ × (17 mol O₂ / 12 mol CO₂) = 19.40 mol O₂

Worked Example 3 — How much MgCl2?

Reaction: 2 HCl + Mg → MgCl₂ + H₂

Problem: 25.6 mL of 0.100 N HCl

Calculation shown step by step:

25.6 mL HCl × (1 L / 1000 mL) × (0.100 mol HCl / 1 L) × (1 mol MgCl₂ / 2 mol HCl) × (95.20 g / 1 mol MgCl₂) = 0.122 g MgCl₂

(Por si viene más teoría)

Actual Yield

Actual yield — The quantity of product actually obtained from a reaction.

Mole Ratio

Mole ratio — We can write it for any two substances represented by an equation.

Double Replacement General Form

Double replacement reaction — AB + CD → AD + CB

Definitions of Reaction Types

Decomposition reaction — When a single compound breaks down into two or more simpler substances.

Combination reaction — The production of a single compound from the reaction of two or more substances.

Combustion — Oxygen is consumed as carbon dioxide and water are produced (in hydrocarbon combustion).

Key Terms

• Coefficient — The number that we place in front of a chemical formula in an equation.
• Balanced chemical equation — The number of atoms of each element is the same on both sides; atoms are balanced.
• Yields — Produces.
• Reactants — The substances at the beginning of the reaction.
• Products — The substances produced by the reaction.
• Chemical reaction — Occurs when substances undergo fundamental changes in identity.
• Chemical equation — Used to present, symbolically, what is taking place during the reaction.
• Catalyst — A substance that is added to speed up a reaction.
• Aqueous solution — A substance that is dissolved in water.