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Chemistry Presentation
(27-39)
By Christopher Hughes
And
Billy Guevara
Chapter 12 (#27-37)
Objectives
Chapter 12
Mole Ratio
Moles -> Moles
Moles-> Grams
Grams-> Grams
Limiting reagent
Excess Reagent
Objectives (continued)
Chapter 13
Properties of solids
Types of phase changes
Chapter 12:Terms to Know
Stoichiometry
Mole ratio
Limiting reagent
Excess reagent
Mole Ratio
A conversion factor derived from the coefficients of a balanced chemical
equation interpreted in terms of moles.
Example
What is the mole ratio of D to A in the generic chemical reaction?
2A + B -> C + 3D
Answer: 3:2
How to find the Mole ratio of a balanced Chemical equation
To find the mole ratio of a balanced chemical equation, first you have to
balance the chemical equation
Fe2O3 + CO -> CO2 + Fe
Fe2O3 + 3CO -> 3CO2 + 2Fe
What is the mole ratio?
Fe2O3 + 3CO -> 3CO2 + 2Fe
Fe2O3 Fe2O3 Fe2O3
3CO
2Fe
3CO2
3CO 3CO
3CO2 2Fe
3CO2
2Fe
Moles -> Moles
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Example: When Iron Rust in air, Iron (III) Oxide is produced. How many
moles of oxygen react with 2.4 moles of iron in the rusting reaction?
Balanced chemical equation
4Fe + 3O2 -> 2FeO3
Answer :1.8 moles of O2
Grams -> Grams
Example: Mercury can be obtained by reacting mercury(II) sulfide with
calcium oxide. How many grams of calcium oxide are needed to produce 36.0
g of Hg?
4HgS + 4CaO -> 4Hg + 3CaS + CaSO4
Grams -> Moles
gH2 mol H2 mol NH3gNH3
given quantity = 5.40g H2
[5.40g H2/1 ] [1 mol H2/2.0g H2] [2mol NH3/ 3 mol H2] = 1.8mol NH3
Limiting Reagent
The reagent (reactant) that is used up first in a reaction and thus determines
the amount of product that can be formed in a reaction.
Excess Reagent
The reagent that is not completely used up
and is left over after the reaction is complete.
action is complete
Sample Problem
Copper reacts with sulfur to form copper(I) sulfide. What is the limiting
reagent when 80.0 g. of Cu reacts with 25.0 g. of S?
Chapter 13 (#38 &39)
Chapter 13: Terms to Know
Boling point
Melting point
Sublimation
Properties of Solids
The general properties of solids reflect the orderly arrangement of their
particles and the fixed locations of their particles. Most solids like the atoms,
ions or molecules are packed tightly together. These solids are dense and not
easy to compress.
Types of phase changes
Types of phase changes include the boiling point which when a liquid is
heated to a temperature at which particles throughout the liquid have
enough kinetic energy to vaporize and the liquid begins to boil. Another
phase change is sublimation which occurs in solids with vapor pressures that
exceed atmospheric pressure at or near room temperature.
That’s all Folks! 