The Law of Conservation of Mass indicates
- No change in total mass occurs in a reaction
- Mass of products is equal to mass of reactants
In an ordinary chemical reaction
- Matter cannot be created or destroyed
- The number of atoms of each element are equal
- The mass of reactants equals the mass of products
The coefficients in an equation may be used to generate conversion factors used in problem solving
These conversion factors are called “mole ratios.”
MOLE RATIOS (from equation coefficients) ARE CONVERSION FACTORS BETWEEN
: number of moles of one compound and number of moles of another compound
Chemical Stoichiometry
using mass and quantity relationships among reactants and products in a chemical reaction to make predictions about how much of a product will be made.
A mole-mole factor
is a ratio of the moles for two
substances in an equation
Reaction Interpretation
- Balance the chemical reaction.
- Develop mole relationships.
- Performe mole to mole calculations.
- Convert moles to gram if required.
A limiting reactant in a chemical reaction is the
substance that
- Is used up first
- Stops the reaction
- Limits the amount of product that can form
Theoretical yield
The maximum amount of product calculated using the balanced equation
Actual yield
The amount of product obtained when the reaction takes place
Percent yield
The ratio of actual yield to theoretical yield.
*percent yield = actual yield (g)/theoretical yield (g) x 100
The heat of reaction
- Is the amount of heat absorbed or released during a reaction
- Is the difference in the energy of the reactants and the products
- Is shown as the symbol DH (delta)
DH=DHproducts-DHreactants
In an exothermic reaction
- Heat is released
- The energy of the products is less than the energy of the reactants
- Heat is a product
In an endothermic reaction
- Heat is absorbed
- The energy of the products is greater than the energy of the reactants
- Heat is a reactant
