Chapter 8 - Quantities in Chemical Reactions Flashcards
Enthalpy of Reaction
the amount of heat released or absorbed by a chem rxn
under conditions of constrant pressure is the ENTHALPY OF RXN
^Hrxn is associated w stoichiometric amounts of reactants and products for the rxn as written
if ^Hrxn= (-) means exothermic
^Hrxn= (+) means endothermic
Stoichiometry
- numerical relationship b/w chem quantities in a balanced equation
- allows us to predict the # of products that formr in a chem rxn based on the # of reactants (and vice versa)
Limiting Reactant
- the reactant that makes the least amount of product
- reactant that is completely consumed in a chem rxn
-i have plenty of eggs and baking soda but a limited amount of flour. the flour will limit the number of pancakes i can make
Theoretical Yield
the amount of product that can be made in a chem rxn based on the amount of limiting reactant.
ex) I have a surplus of eggs and baking soda but a limited amount of flour. The #of pancakes I can make (theoretical yield) is based on the limited amount of flour (limiting reactant)
Actual Yield
if the theoretical yield is the number of products that can be made if everything goes smoothly, the actual yield is the amount of product actually produced in a chem rxn
ex) theoretically, we should have been able to make 15 pancakes with the reactants we have. however, some were burnt/dropped on the floor. So the ACTUAL YIELD is 11 pancakes
Percent Yield
percentage of theoretical yield actually obtained
PercentYield=
actual yield/theor yield
Enthalpy
the amount of thermal energy emitted or absorbed by a chem rxn under conditinis of constant pressure can be quantified with a function called Enthalpy
Enthalpy Reaction
the amount of thermal energy (or heat) that is emitted or absorbed when a rxn occurs at a constant pressure
^Hrxn, (-) means exothermic, (+) means endothermic
