Name ________________________________
Period ____
Regents Review 4: Stoichiometry
Review Book Topic 2,3
23
multiply by 6.02 x 10
divide by GFM
grams
atoms/
molecules
moles
23
multiply by GFM
divide by 6.02 x 10
multiply by
22.4 L
divide by
22.4 L
liters
(gases only)
A. The Mole
a. Mole is defined as the number of atoms of carbon present in 12.000 grams of C-12.
o The number of particles in a mole of a substance is 6.022 x 1023, which is
called Avogadro’s number (Think 1 dozen means 12, 1 mole is 6.022 x 1023
particles)
o The gram formula mass of any substance is the mass of one mole of the
substance.
b. Converting grams to moles or moles to grams use formula on the reference table
c. Converting moles to atoms (particles) for elements or atoms to moles (see above)
d. Converting moles to liters or liters to moles (see above)
B. Determining Missing Mass in Equations (conservation of mass)
mass of reactants=mass of products
example: If 103.0 g of potassium chlorate are decomposed to form 62.7 grams of potassium
chloride and oxygen gas according to the equation 2KClO3 → 2KCl + 3O2, how many
grams of oxygen are formed?
2KClO3 → 2KCl + 3O2
?
103.0 g = 62.7 g + ?(mass of oxygen)
-62.7 g -62.7 g
40.3 g = ? (grams of oxygen)
C. Molarity- use formulas on the reference table
D. Molecular vs. Empirical Formula
C3H6 is the molecular formula, CH2 is the empirical formula (simplest integer ratio)
E. Mole relations in balanced equations
Given quantity = Given quantity
Moles in equation
Moles in equation
How many moles of water will be produced from the
complete combustion of 3.0 mol of ethane according to
the following equation?
2C2H6 (g) + 7 O2 (g) 4CO2 + 6H2O (g)
3 mol C2H6 = ? mol H2O
2 mole C2H6
6H2O
Solve for ? mol water = 9
_____1. What is the empirical formula of the
compound whose molecular formula is P4O10?
(1) PO (2)PO2 (3) P2O5 (4) P8O20
_____2. Which gas sample at STP has the
same total number of molecules as 2.0 liters of
CO2(g) at STP?
(1) 5.0 L of CO2(g) (3) 3.0 L of H2S(g)
(2) 2.0 L of Cl2(g) (4) 6.0 L of He(g)
Given the formula representing a hydrocarbon:
____3. The molecular formula and the empirical
formula for this hydrocarbon are
(1) C5H10 and CH2 (3) C4H8 and CH2
(2) C5H10 and CH3 (4) C4H8 and CH3
_____4. Which formula is both a molecular and
an empirical formula?
(1) C6H12O6 (3) C3H8O
(2) C2H4O2 (4) C4H8
_____5. The molarity of an aqueous solution of
NaCl is defined as the
(1) grams of NaCl per liter of water
(2) grams of NaCl per liter of solution
(3) moles of NaCl per liter of water
(4) moles of NaCl per liter of solution
_____6. The gram-formula mass of NO2 is
defined as the mass of
(1) one mole of NO2
(2) one molecule of NO2
(3) two moles of NO
(4) two molecules of NO
_____7. What is the molarity of 1.5 liters of an
aqueous solution that contains 52 grams of
lithium fluoride, LiF, (gram-formula mass 26
grams/mole)?
(1) 1.3 M
(3) 3.0 M
(2) 2.0 M
(4) 0.75 M
_____8. A compound has the empirical formula
CH2O and a gram-formula mass of 60. grams
per mole. What is the molecular formula of this
compound?
(1) CH2O
(3) C3H8O
(2) C2H4O2
(4) C4H8O4
_____9. A 1.0-mole sample of krypton gas has a
mass of
(1) 19 g (3) 39 g
(2) 36 g
(4) 84 g
_____10.What is the empirical formula for a
compound with the molecular formula
C6H12Cl2O2?
(1) CHClO
(3) C3H6ClO
(2) CH2ClO
(4) C6H12Cl2O2
_____11.The compounds C2H4 and C4H8 have
the same
(1) freezing point at standard pressure
(2) boiling point at standard pressure
(3) molecular formula
(4) empirical formula
____12. Which sample of HCl(aq) contains the
greatest number of moles of solute particles?
(1) 1.0 L of 2.0 M HCl(aq)
(2) 2.0 L of 2.0 M HCl(aq)
(3) 3.0 L of 0.50 M HCl(aq)
(4) 4.0 L of 0.50 M HCl(aq)
_____13. Given the balanced equation
representing a reaction:
2Fe(s)+ 3Cu2+(aq)→2Fe3+(aq)+3Cu(s)
When the iron atoms lose six moles of
electrons, how many moles of electrons are
gained by the copper ions?
(1) 12 moles
(3) 3 moles
(2) 2 moles
(4) 6 moles
_____14.Given the balanced equation
representing a reaction:
Mg(s) + Ni 2+ (aq) →Mg 2+ (aq) + Ni(s)
_____13. What is the total number of moles of
electrons lost by Mg(s) when 2.0 moles of
electrons are gained by Ni 2+(aq)?
(1) 1.0 mol
(3) 3.0 mol
(2) 2.0 mol
(4) 4.0 mol
_____15. Which sample at STP has the same
number of molecules as 5 liters of NO2(g) at
STP?
(1) 5 grams of H2(g)
(2) 5 liters of CH4(g)
(3) 5 moles of O2(g)
(4) 5 ∙1023 molecules of CO2(g)
_____16.The number of moles of ions in 1 mol
of copper(II)phosphate is
1) 1
2) 4 3)2
4) 5
_____17. What is the gram formula mass of
K2CO3?
(1) 138 g (2) 106 g (3)99 g (4) 67 g
_____18. What is the total number of atoms
contained in 2.00 moles of nickel?
(1) 58.9 (2)118 (3) 6.02 x 1023 (4)1.2 x 1024
_____19. Which solution is the most
concentrated?
(1) 1 mole of solute dissolved in 1 liter of
solution?
(2) 2 moles of solute dissolved in 3 liters
of solution?
(3) 6 moles of solute dissolved in 4 liters
of solution?
(4) 4 moles of solute dissolved in 8 liters
of solution?
_____20. What is the total number of moles
of H2SO4 needed to prepare 5.0 liters of a 2.0
M solution of H2SO4?
(1) 2.5 (2)5.0 (3)10 (4) 20
21. During a test, a propane lantern is operated
for three hours and consumes 5.0 moles of
propane from the lantern’s tank. The balanced
equation below represents the combustion
of propane.
C3H8 + 5O2 →3CO2 + 4H2O + energy
Determine the total number of moles of CO2
produced in the combustion of propane.[1]
19. Given the balanced equation representing a
reaction:
C3H8(g) + 5O2(g) →3CO2(g) + 4H2O(g)
What is the total number of moles of O2(g)
required for the complete combustion of
1.5 moles of C3H8(g)?
20. In an experiment, 40.0 milliliters of HCl(aq)
is completely neutralized by 20.0 milliliters of
0.10 M NaOH(aq). Calculate the molarity of
the titrated acid in this trial. Your response must
include both a numerical setup and the calculated
result. [2]
21. Determine the mass of 5.20 moles of C6H12
(gram-formula mass = 84.2 grams/mole).[1]
22. An unsaturated solution is made by
completely dissolving 20.0 grams of NaNO3 in
100.0 grams of water at 20.0°C.
Show a correct numerical setup for calculating
the number of moles of NaNO3 (gram-formula
mass = 85.0 grams per mole) used to make
this unsaturated solution and solve. [1]