THE MOLE
Using the mole and molar mass, make conversions between moles, mass and number of particles.
Use molar mass to calculate percent composition, empirical formula, and molecular formula.
A chemical used in batteries is 63.0% Manganese and 37.0% Oxygen. What is the empirical formula?
Answer: MnO2
The empirical formula of a compound is P2O5. The molar mass of the compound is 284 g/mol. What is the molecular formula?
Answer: P4H10
STOICHIOMETRY
Convert from one substance to anotherDetermine amount of reactant/productDetermine limiting reactant/excessDetermine theoretical & percent yieldUse density to convert between
substances
Using the following balanced chemical reaction:
CH4(g) + 2O2(g) CO2(g) + 2H2O(g)
How many molecules of oxygen are needed to react with 2.45 mol of CH4?
2.95 x 1024 molecules O2
What volume of hydrogen gas is produced if there are 112 g NH3 in the following reaction at 1.15 atm and 23
degrees Celsius? 2NH3(g) N2(g) + 3H2(g)
208 L
If reactant “A” runs out before reactant “B” and the reaction stops, then reactant “A” is known as the …
LIMITING REACTANT
Using the following reaction,
2Na(s) + 2H2O(g) 2NaOH(aq) + H2(g)
If you have 15.2 g of Na and 12.5 g of H2O, how many grams of H2 gas can be made?
0.658 g H2
If the theoretical yield of a reaction is 125 g and the actual yield is 115 g, what is the percent yield?
92.0 %
GASES
STP valuesUse gas laws to determine pressure,
volume, and temperature.Use gas laws to determine moles or grams
or molar mass.Use gas laws and stoich. to determine
amounts of reactants and products.
A sample of gas has a volume of 25 mL and a temperature of 65oC. What will the volume be if the temperature is raised to 125oC?
29 mL
How many grams of gas are present in a sample that has a molar mass of 70.0 g/mol and occupies 2.00 L at 117 kPa and 35.1oC?
6.36 g
What is the pressure in atmospheres of a 0.108 mol sample of helium gas at a temperature of 20.0oC if its volume is 0.505 L?
5.14 atm
Calculate the mass of solid ammonium nitrate that must be used to obtain 0.100 L of dinitrogen monoxide gas at STP.
NH4NO3(s) N2O(g) + 2H2O(g)
0.357 g
SOLUTIONS
Solubility (“like dissolves like”)Concentration (molarity)Vocab
unsaturated, saturated, supersaturated, soluble, insoluble, miscible, immiscible
Electrolytes and Non-Electrolytes
How many milliliters of a 0.850 M solution of sodium thiosulfate, Na2S2O3, contain 0.350 mol of Na2S2O3?
0.412 L
A ____________ solution contains the maximum amount of solute it can hold. An __________ solution contains less than the maximum amount. A ____________ solution contains more than the maximum amount.
saturated, unsaturated, supersaturated
Reactants must collide (with enough energy and the correct orientation) in order to produce an activated complex and form product.
Describe collision theory.
How does a catalyst increase the rate of a reaction?
It lowers the activation energy by creating an alternate path.
How does the rate of a reaction change over time?
The rate slows down because the concentration of the reactants decreases over time.
EQUILIBRIUM
Completion vs. ReversibleRates of Reactions at EquilibriumKeqLeChatelier’s PrincipleEquilibrium ExpressionsCalculating KKsp
A ________ reaction is represented by , while a ______ reaction is represented by .
completion, reversible
2 NO2 (g) N2O4 (g) + Energy
What happens if we… Lower the Temperature
Increase N2O4
Decrease NO2
Increase PressureIncrease Volume
Shift rightShift leftShift leftShift rightShift left
What does it mean if the reaction shifts to the right? How would the amounts of reactants and products change?
The reactions favors the forward reaction so the amounts of reactants decrease and products increase.
Equilibrium Expressions
Write the equilibrium constant for the following reaction:
N2 (g) + 3 H2(g) 2 NH3(g)
Keq = Keq = [NH[NH33]]22 [N[N22][H][H22]]33
Calculate Keq for the reaction below if [S2] = 0.0540 M, [H2] = 0.0377 M, and [H2S] =
0.184 M.2 H2S (g) 2 H2(g) + S2(g)
Keq = 2.27 x 10-3
What does a large value for Keq mean? A small value for Keq?
Large means products are favored at equilibrium while small means reactants are favored
Which of the substances below is most soluble? Least soluble?CaF2 – 3.5 x 10-11
PbCrO4 – 2.3 x 10-13
Al(OH)3 – 4.6 x 10-33
MgCO3 – 6.8 x 10-6
Most soluble = MgCO3
Least soluble = Al(OH)3
ACIDS & BASES
Electrolytes and Strong vs. WeakBronsted – LowryAmphoprotic – AmphotericpH calculationsTitrations
Strong acids and bases ionize ___________ while weak acids and bases ionize __________.
completely, partially
Label the A, B, CA, CB in the following reaction:
HSO4- (aq) + H2O (l) H3O+ (aq) + SO4
2-
HSO4- (aq) + H2O (l) H3O+ (aq) + SO4
2-
A B CA CB