Presentation on theme: "WHAT IS STOICHIOMETRY?. INTERPRETING BALANCED CHEMICAL EQUATIONS STOICHIOMETRY IS THE STUDY OF THE QUANTITATIVE, OR MEASURABLE, RELATIONSHIPS THAT EXIST."— Presentation transcript:
INTERPRETING BALANCED CHEMICAL EQUATIONS STOICHIOMETRY IS THE STUDY OF THE QUANTITATIVE, OR MEASURABLE, RELATIONSHIPS THAT EXIST IN CHEMICAL FORMULAS AND CHEMICAL REACTIONS. N 2 H 4 + 2 H 2 O 2 -> N 2 + 4 H 2 O The coefficients can indicate the following: 1 molecule N 2 H 4 + 2 molecules H 2 O 2 -> 1 molecule N 2 + 4 molecules H 2 O 1 mole N 2 H 4 + 2 moles H 2 O 2 -> 1 mole N 2 + 4 moles H 2 O 32 g N 2 H 4 + 2(34 g) H 2 O 2 -> 28 g N 2 + 4 (18 g) H 2 O
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 forms Factors 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