Part 4
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how do you calculate number of moles present? ex: how many moles are in 9.52g of MgCl2?
mol = weight of sample (g)/ mw mol = 9.52 / 95.21 = .10 mol
to find moles given grams of a compound, what formula is used?
mol= g/mw ``` g= grams of sample (mw= mw of compound) ~~~
what is the formula for percent composition of an element?
% composition = mass of X in formula / mw x 100
what is an ionic equation?
includes spectator ions that do not participate in the actual reaction (displacement rxn)
what is a net ionic reaction?
shows only the species involved in the reaction, not the spectators (displacement rxn)
what type of reaction is double displacement and involves an acid reacting with a base to produce salt and water?
neutralization
how do you calculate theoretical yield?
theor. = (starting amount)(mw product) / ( mw of starting)
how do you calculate percent yield?
% yield= product amount/ theo. yield
the slowest step in a proposed rxn mechanism is known as what?
rate-determining step
how are orders of rxn determined?
experimentally
what is an enthalpy change?
represented by deltaH; the difference between the the potential energy of the products and the potential energy of the reactants
what does a negative delta H represent?
an exothermic reaction; heat is given off
what does a positive delta H represent?
an endothermic reaction; heat absorbed
as a rule of thumb, the rate of a reaction will double approximately, for each increase in temperature of how much?
10 degree Celsius increase= rate of rxn doubles approximately
what are the four main factors affecting reaction rate?
• reactant concentrations • temperature • medium • catalysts
when the forward rate of rxn = the reverse, what is the rxn said to be at?
equilibrium
what is Kc? what is it denotated as when dealing with gas?
equilibrium constant kp= gas
neutral, nonmetallic elements will always have electrons in what shell?
p
how many electrons can a p-subshell hold?
6
if a compound contains NH4 is it ionic or covalent bond?
ionic, even though it doesn’t contain a metal