WorksheetsCHEM - Mole & Percentage Composition
Total questions: 59
Worksheet time: 3hrs 34mins
Where are the numbers for a mole ratio found?
They are part of the chemical formulas for the reactants / products.
They are given in the problem.
They are found on the periodic table for those elements.
They are found as coefficients in the reaction's balanced chemical equation.
2 C2H6 + 7 O2 → 4 CO2 + 6 H2O
Ethane (C2H6) combusts in the above reaction. What is the mole ratio of carbon dioxide to water?
2 C2H6 + 7 O2 → 4 CO2 + 6 H2O
A problem asks how many moles of oxygen gas are needed to react completely with 6 moles of ethane (C2H6). What is the second step in setting up the problem?
2 C2H6 + 7 O2 → 4 CO2 + 6 H2O
New problem: If 16 moles of carbon dioxide are formed by this reaction, how many moles of water were also produced?
4 mol H2O
6 mol H2O
24 mol H2O
96 mol H2O
384 mol H2O
2 C2H6 + 7 O2 → 4 CO2 + 6 H2O
New problem: If 3.5 moles of oxygen gas are used up as ethane combusts completely, how many moles of carbon dioxide are produced?
0.5 mol CO2
0.57 mol CO2
2.0 mol CO2
3.0 mol CO2
3.5 mol CO2
The mass of one mole of an element is equal to
its atomic number from the periodic table, but in amus.
its atomic mass from the periodic table, but in amus.
its atomic mass from the periodic table, but in grams.
its atomic number from the periodic table, but in grams.
What is the molar mass of PbSO4?
303.27 g/mol
255.27 g/mol
163.87 g/mol
372.27 g/mol
Shivani measures out 6.0 moles of epsom salt (MgSO4) to put in her bath. How many grams of MgSO4 went in the bath?
3.6 x 1024 g
720 g
0.050 g
340 g
Determine the mass of 4.20 moles of C6H12
353 g
0.0499 g
337 g
2.53 x 1024 g
What is the mass of 1.2 x 1024 atoms of C?
2.0 grams
24 grams
0.17 grams
1.4 x 1025 grams
Calculate the number of atoms in 0.0340 g Zn.
5.20 x 10-4 atoms Zn
3.13 x 1023 atoms Zn
3.13 x 1020 atoms Zn
2.05 x 1022 atoms Zn
How many grams are in 1.2 moles of neon?
0.059 grams
7.2 x 1023 grams
2.0 x 10-24 grams
24 grams
How many moles are in 98.3 grams of aluminum hydroxide, Al(OH)3?
1.26 moles
0.8 moles
7,670 moles
1.63 x 10-22 moles
To melt the ice, Juan throws 455 g of calcium chloride, CaCl2 on his sidewalk. How many moles of CaCl2 did he throw?
50,500 moles
4.10 moles
7.56 x 10-22 moles
111 moles
What is the molar mass when you have 4 moles of CO2?
176 grams
54 grams
128 grams
280 grams
How many moles of Na contain 1.45 x 1021 atoms of Na?
8.73 x 1044 moles
8.73 moles
0.00241 moles
2.41 x 1044 moles
What are the units for Avogadro's number?
meters
particles
grams
liters
atoms in
2.50 moles of zinc.
Ga2(SO3)3
48.86 g of cobalt is equal to how many moles of cobalt?
2879 moles
8.291 moles
.8291 moles
.829 moles
Convert 86.235 g of diphosphorus pentaoxide to moles.
12240 moles
1.8747 moles
.608 moles
.60755 moles
how many atoms are contained in a 456 g sample of carbon dioxide?
10.34 atoms
6.237 x 1024 atoms
1.871 x 1025atoms
2.079 x 1024 atoms
What would be the mass of 9.76 x 1022 formula units of SrCl2?
.1622 g
25.7 g
20.0 g
.3589 g
A sample of AlCl3 contains a total of 4.515 x 1027 atoms of chlorine. What must be the mass of this sample?
2.500 x 105 g
1.000 x 106 g
18.75 g
3.333 x 105 g
How many molecules are there in 31.8 moles of water? (H2O has a molar mass of 18.0 g/mol)
572 g
1.91 x 1025 molecules
5.28x 10-25 molecules
1.77 g
Vitamin C, also known as ascorbic acid, is water soluble and cannot be produced by the human body. Each day, a person's diet should include a source of Vitamin C, such as orange juice. Ascorbic acid has a molecular formula of C6H8O6 and a molar mass of 176 grams per mole.
Determine the number of moles of vitamin C in an orange that contains 0.171 grams of vitamin C.
30.1 moles
1030 moles
.000971 moles
.0001 mole
Calculate the number of moles of chlorine atoms in 55g of copper (II) chloride.
0.41 moles
0.82 moles
1.6 moles
.20 moles
What is the mass of 0.75 moles of (NH4)3PO4?
0.0044 g
91 g
110 g
74 g
How many molecules are present in 135 g of Teflon C2F4
6.13 x 1023 molecules
5.13 x 1023 molecules
8.13 x 10 23 molecules
9.13 x 1023 molecules
What is the molar mass of calcium hydroxide, Ca(OH)2?
74.1 g/mole
57.1 g/mole
58.1 g/mole
57.1 u
What is the general formula for the computation of percentage composition of the given element?
% mass of element = mass of element in the compound divided by mass of the compound times 100
% mass of element = mass of element in the compound divided by mass of the compound
% mass of element = mass of element in the compound divided by 100
% mass of element = mass of element in the compound
What is the percent by mass of magnesium in MgO?
20%
40%
50%
60%
What is the percent by mass of chlorine in NaCl?
39%
61%
35%
35%
What is the percent by mass of fluorine in CaF2 (gram-formula mass = 78 g/mol)?
24%
49%
49%
65%
Find the percent composition of Cu2S?
%Cu= 67.987 %S= 32.013
%Cu= 79.854 %S= 20.145
%Cu= 35.946 %S= 64.054
What is the percent composition of Benzene, C6H6?
C = 50%
H = 50%
C = 85.7 %
H = 14.3%
C = 92.2%
H = 7.8%
C = 71.9%
H = 28.1%
Find the molar mass of KCl
36 g/mol
36 g/mol
74 g/mol
178 g/mol
O = 89.9%
O = 33.3%
O = 89.9%
O = 80%
Carbon monoxide, a deadly gas, has a chemical formula of CO (one carbon atom with one oxygen atom). If you look at the total atomic mass of CO, does carbon or oxygen make up more of the mass?
carbon
oxygen
they are exactly the same
it is impossible to tell
What percentage of the total atomic mass of carbon monoxide (CO) is composed of carbon?
29%
43%
57%
73%
What percentage of the total atomic mass of carbon monoxide (CO) is composed of oxygen?
29%
43%
57%
73%
What percentage of the total atomic mass of magnesium bromide (MgBr2) is composed of magnesium?
13%
43%
63%
87%
What percentage of the total atomic mass of lithium phosphide (Li3P) is composed of phosphorus?
13%
29%
40%
60%
