The Massive Mole Review
Complete each question on your own sheet of
paper. Show your work .
Warm Up Practice
1. How many atoms are found in one mole of mercury? 6.02 x 1023 atoms
2. 84.7 g of lead represents how many moles of lead? 0.409 mol
3. How many moles are represented in 201.7 g of copper (II) chloride? 1.500 mol
4. How many atoms of bismuth are found in 15 g of bismuth (III) bicarbonate?
2.3 x 1022 atoms
5. 1.9718 x 1020 molecules of boron trioxide weighs how many grams? 0.019263
g
6. How many molecules are in 10.5 g of diphosphorus pentaoxide? 4.45 x 1022
atoms
7. What is the molar mass of iron (III) phosphate? FePO4 is 150.8 g/mol
Percent Composition
1. Find the percent composition of each element in a compound that is 15.62 g
nitrogen (55.47%) and 12.54 g of carbon (44.53%).
2. Find the percent composition of a compound that is 10.12 g aluminum (36.08%)
and 17.93 g of sulphur (63.92%).
3. Calculate the percent by mass of carbon in glucose. 39.99%
4. Calculate the percent by mass of copper in copper (II) bromide. Cu = 28.45%
5. Calculate the percent composition of each element in K3N. K = 89.33% and N =
10.67%
6. Calculate the percentage composition of each element in Al2(SO4)3. Al = 15.77%,
S = 28.11%, and O = 56.12%
7. Find the percent composition of each element in a compound made of 12.5 g
barium (33.34%), 16.44 g oxygen (43.85%), and 8.551 g carbon (22.81%).
8. Find the percent composition of each element in a compound made of 37.5 g iron
(51.84%), 8.4 g chlorine (11.61%), and 26.44 g oxygen (36.55%).
Empirical and Molecular Formulas
1. A new barium-nitrogen compound was discovered. When the sample was
analyzed, it was found to be 76.5% (by weight) barium. What is the empirical
formula of the sample? BaN3
2. There are two common oxides of sulphur. One contains 32 g of sulphur for each
32 g of oxygen. The other oxide contains 32 g of sulphur for each 48 g of oxygen.
Find the empirical formula of each. SO2 & SO3
3. When 0.062 g of red phosphorus burns, 0.142 g of phosphorus oxide is formed.
What is the empirical formula of this phosphorus oxide compound? (assume no
mass is lost during reaction) P2O5
4. A compound is 24.4% Ca, 17.1% N and 58.5% O. Calculate the empirical
formula. Ca2N2O6
5. A compound is composed of 19.01 g of carbon, 18.48 g of nitrogen, 25.34 g of
oxygen, and 1.58 g of hydrogen. Find the empirical formula of this compound.
C6N5O6H6
6. A chemical compound is analyzed and found to contain 5.61 g of Mg and 36.9 g
of Br. The molar mass of this compound is 552.3 g/mol. Find the empirical and
molecular formulas? MgBr2, Mg3Br6
7. A compound is composed of 16.66 g of carbon and 3.49 g of hydrogen. The molar
mass of the compound is 58 g. Find the empirical formula and molecular formula
for this compound. C2H5, C4H10
8. A compound is composed of 7.20 g of carbon, 1.20 g of hydrogen, and 9.60 g of
oxygen. The molar mass of the compound is 180 g. Find the empirical and
molecular formulas for this compound. CH2O & C6H12O6
9. What is the molecular formula of a compound that is analyzed and found to
contain the following elements in the following percentage: carbon = 27.3 % and
oxygen = 72.7 % (percent by mass)? The molecular molar mass is 308 g/mol.
C7O14
10. The empirical formula for a compound is C2H5O and its molecular mass is 135
g/mol. Determine the molecular formula. C6H15O3
11. Hydroquinone, a chemical used for photographic developing, is 65.45% C, 5.51%
H and 29.09% O. Calculate the empirical and molecular formula. The molecular
mass is 110 g/mol. C3H3O & C6H6O2
12. A sample of "mung" is analyzed and found to contain the following element
amounts: carbon = 19.2 g and nitrogen = 22.1 g. What is the empirical formula?
CN
13. A sample of "monkey mung" was also found at the same time and analyzed. It
was found to contain the following element amounts: Mg = 8.062 g and O = 3.99
x 1023 atoms and a molecular molar mass of 450 g/mol. Find the molecular
formula. Mg8O16
Molarity
1. How many moles of Na2CO3 are there in 10.0 L of 2.0 M soluton? 20. mol
2. How many moles of Na2CO3 are in 10.0 mL of a 2.0 M solution? 2.0 x 10-2 mol
3. How many moles of NaCl are contained in 100.0 mL of a 0.20 M solution? 0.20
mol
4. What weight (in grams) of H2SO4 would be needed to make 750.0 mL of 2.00 M
solution? 147g
5. What volume (in mL) of 18.0 M H2SO4 is needed to contain 2.45 g H2SO4? 1.39
mL
6. What volume (in mL) of 12.0 M HCl is needed to contain 3.00 moles of HCl?
250. ml
7. How many grams of Ca(OH)2 are needed to make 100.0 mL of 0.250 M solution?
1.850g
8. What is the molarity of a solution made by dissolving 20.0 g of H3PO4 in 50.0 mL
of solution? 4.08M
9. What weight (in grams) of KCl is there in 2.50 liters of 0.50 M KCl solution?
93.3g
10. What is the molarity of a solution containing 12.0 g of NaOH in 250.0 mL of
solution? 1.20
11. Determine the molarity of these solutions:
a) 4.67 moles of Li2SO3 dissolved to make 2.04 liters of solution. 2.29M
b) 0.629 moles of Al2O3 to make 1.500 liters of solution. 0.430M
c) 4.783 grams of Na2CO3 to make 10.00 liters of solution. 4.512 x 10-3 M
d) 0.897 grams of (NH4)2CO3 to make 250 mL of solution. 3.74 x 10-2 M
e) 0.0348 grams of PbCl2 to form 45.0 mL of solution. 2.77 x 10-3 M
12. Determine the number of moles of solute to prepare these solutions:
a) 2.35 liters of a 2.00 M Cu(NO3)2 solution. 4.70 mol
b) 16.00 mL of a 0.415-molar Pb(NO3)2 solution. 6.64 x 10-3 mol
c) 3.00 L of a 0.500 M MgCO3 solution. 1.50 mol
d) 6.20 L of a 3.76-molar Na2O solution. 23.3 mol
13. Determine the grams of solute to prepare these solutions:
a) 0.289 liters of a 0.00300 M Cu(NO3)2 solution. 0.163 g
b) 16.00 milliliters of a 5.90-molar Pb(NO3)2 solution. 31.3 g
c) 508 mL of a 2.75-molar NaF solution. 58.8 g
d) 6.20 L of a 3.76-molar Na2O solution. 1.44 x 103 g
e) 0.500 L of a 1.00 M KCl solution. 37.3 g
f) 4.35 L of a 3.50 M CaCl2 solution. 1.69 x 103 g
14. Determine the final volume of these solutions:
a) 4.67 moles of Li2SO3 dissolved to make a 3.89 M solution. 1.20 L
b) 4.907 moles of Al2O3 to make a 0.500 M solution. 9.81 L
c) 0.783 grams of Na2CO3 to make a 0.348 M solution. 2.72 x10-2 L
d) 8.97 grams of (NH4)2CO3 to make a 0.250-molar solution. 0.379 L
e) 48.00 grams of PbCl2 to form a 5.0-molar solution. 3.5 x 10-2 L
15. What is the final concentration when you:
a) add 400.0 mL of 1.2M KCl to 300.0 mL of water 0.69 M
b) add 150.7 mL of 0.8 CaO to 137.8 mL of water 0.4M
c) add 327.1 mL of 1.80M LiOH to 500.0 mL of 1.70M LiOH 1.74 M
d) add 400.0 mL of 0.80M LiOH to 600.0 mL of 0.400M LiOH 0.56 M
16. What volume of water is added to:
a) 30.0 mL of 1.0M KCl to give a final concentration of 0.80M KCl 0.0075L
a) 50.0 mL of 6.0M KCl to give a final concentration of 3.2M KCl 0.044 L