WHAT IS STOICHIOMETRY?

INTERPRETING BALANCED CHEMICAL EQUATIONS

STOICHIOMETRY IS THE STUDY OF THE QUANTITATIVE, OR MEASURABLE, RELATIONSHIPS THAT EXIST IN CHEMICAL FORMULAS AND CHEMICAL REACTIONS.

N2H4 + 2 H2O2 -> N2 + 4 H2O

The coefficients can indicate the following: 1 molecule N2H4 + 2 molecules H2O2 -> 1 molecule N2 + 4 molecules

H2O

1 mole N2H4 + 2 moles H2O2 -> 1 mole N2 + 4 moles H2O

32 g N2H4 + 2(34 g) H2O2 -> 28 g N2 + 4 (18 g) H2O

HOW DO WE CALCULATE THE AMOUNT OF PRODUCT?

WHAT IS A LIMITING REACTANT?

The reactant that limits the amount of product formed

The reactant that in an experiment is all used up

Measures the efficiency of a reaction carried out in the lab

Theoretical yield – the maximum amount of product that can form during a reaction (calculated)

Actual yield – how much actually formsFactors causing % yield to be less than 100

Reaction not completing Impure reactants Loss of product during filtration Careless measurement

Percent Yield

HOW DO WE DETERMINE PERCENT YIELD?

Although you can determine the amount of product that will be produced in a chemical reaction, in reality, that calculated amount is not always the actual amount obtained from the reaction.

Shows the amount of heat produced or absorbed by a reaction

Every reactant will have a certain heat content, or enthalpy (H)

The change in enthalpy (H) will tell us if the reaction is exo or endothermic

Thermochemical Equation

If H is positive, reaction is endothermic (heat is a reactant)

If H is negative, reaction is exothermic (heat is a product)

Change in Enthalpy