Skill Practice 30
Name: ______________________________
Date: _______________
Hour: _____
1. Calculate the number of molecules in 210 grams of water.
7.02x1024 molecules
2. If you have 6.25 x 1024 molecules of sulfur tetrafluoride, how many grams do you have?
1120 g
3. Define what a mole is. Don’t give a number, give a definition in words.
The quantity of atoms needed to equal the substances atomic mass in units of grams.
4. What is the mass of 3.45 moles of aluminum sulfate?
1180 g
5. Consider zinc acetate and find its “formula mass” and its “molar mass”. Include units for
each.
Formula mass: 183.4 amu
Molar mass: 183.4 g/mol
6. If you have 245 grams of lithium carbonate, how many moles do you have?
3.32 mol
7. How many gold atoms do you have if you have 400 grams of gold?
1.22x1024 atoms
8. 68.5 grams of a certain compound contains 5.25 x 1023 molecules. What is the molar mass of
the compound?
78.5 g/mol
9. How many grams are there in a container of 2.26 x 1025 molecules of dinitrogen trisulfide?
4,670 g
10. How many molecules are in 325 g of N2O5?
1.81x1024 molecules
Skill Practice 31
Name: ______________________________
Date: _______________
Hour: _____
1. What is the percent by mass of carbon in Al2(CO3)3?
15.4%
2. Find the percent composition of oxygen in each of the following compounds:
a) Na2O
b) Mg(NO3)2
25.8%
64.7%
3. Find the percent composition of nitrogen in each of the following compounds.
a) (NH4)2O
b) N3O5
53.8%
34.4%
4. What is the empirical formula of a compound that contains 25.9% nitrogen (N) and 74.1%
oxygen (O) by mass?
N2O5
5. What is the molecular formula of a compound that has an empirical formula of NO2 and a
molar mass of 138 g/mol?
N3O6
6. A compound contains 64.3% carbon, 7.14% hydrogen and 28.6% oxygen. The molecular
formula has a molecular mass of 448 amu.
a) What is the empirical formula for this compound?
C3H4O
b) What is the molecular formula for this compound?
C24H32O8
7. A certain compound contains 26.35% C, 3.30% H and 70.35% O. If the molecular mass of
this compound is 819 amu, what is the molecular formulas of the compound?
C18H27O36
Skill Practice 32
Name: ______________________________
Date: _______________
Hour: _____
1. Consider the reaction in which 410 g of Ca(NO3)2 react with just the right amount of lithium
metal in a single replacement reaction.
a) How many grams of lithium are required?
35.0 g
b) How many grams of each product can be produced?
345 g LiNO3
100g Ca
2. When 250 g of Na2SO4 reacts with plenty of Ca3P2 according to the following balanced
equation, how many grams of Na3P will be produced?
3 Na2SO4 + Ca3P2  2 Na3P + 3 CaSO4
130g Na3P
265g CaSO4
3. Consider the following combustion reaction: 2 C4H10 + 13 O2  8 CO2 + 10 H2O. If 75.3 g
of C4H10 react with plenty of O2, what mass of CO2 and H2O can be produced?
229g CO2
117g H2O
4. Consider the following balanced equation: 3Ca(NO3)2 + 2AlCl3  2Al(NO3)3 + 3CaCl2. If
210.5g of calcium nitrate react, what is the mass of each product that can be produced?
409.8g Al(NO3)3
142g CaCl2
5. When 53.6 g of calcium carbonate react with plenty of aluminum fluoride, how many grams
of each product can be produced?
41.8g of each product will be produced