Oxygen and Significant Figures
Chemistry 121 Worksheet 3 (Fall 2013)
1)
Determine the mass, in g, of
a) 7.34 mol N 2O 4
b) 3.16 ×1024 O 2 molecules
c) 18.6 mol CuSO 4 ⋅ 5 H 2O
d) 4.18 ×1024 molecules of C2 H 4 (OH) 2
e) a quantity of the amino acid lysine, C6 H14 N 2O 2 , containing 3.03 mol N atoms
2)
Determine the number of moles of
a) N atoms in a sample of C7 H 5 (NO 2 )3 that has the same number of O atoms as 12.4 g C6 H12O6
b) Br2 in a sample consisting of 2.17 ×1024 Br atoms
c) N atoms in 43.5 g of Mg(NO3 ) 2
d) Br2 in a sample consisting of 2.65 L liquid bromine (d = 3.10 g/mL)
3)
Explain which of the following statement(s) is (are) correct for sorbic acid, C6H8O2.
a) it has a C:H:O mass ratio of 3:4:1.
b) it has the same mass % composition as acrolein, C3H4O.
c) it has the same empirical formula as aspidinol, C12H16O4.
d) it has four times as many H atoms as O atoms, but four times as much O as H by mass.
4)
For the compound Ge[S(CH2)4CH3]4, determine
a) the total number of atoms in one formula unit
b) the ratio, by number, of C atoms to H atoms to 3 significant figures
c) the ratio, by mass, of Ge to S to 3 significant figures
d) the number of g S in 1 mol of the compound to 3 significant figures
e) the number of C atoms in 33.10 g of the compound
5)
Determine the mass % O in the mineral malachite, Cu 2 (OH) 2CO3 .
6)
Determine the mass % H2O in the hydrate Cr(NO3 )3 ⋅ 9H 2O . Express your answer to 4 significant figures.
7)
Determine the empirical formula of the rodenticide warfarin (a carbon-hydrogen-oxygen compound), which consists of 74.01% C and 20.76% O by mass.
8)
Selenium forms two oxides. One has 28.8% O by mass and the other has 37.8% O. What are the formulas of these two oxides?
9)
Adenine is a carbon-hydrogen-nitrogen compound with 44.45% C and 3.73% H by mass. It’s molecular mass is 135.14 u. What is its molecular formula?
10) Combustion of a 0.312 g sample of a carbon-hydrogen-nitrogen
1)
Determine the mass, in g, of
a) 7.34 mol N 2O 4
b) 3.16 ×1024 O 2 molecules
c) 18.6 mol CuSO 4 ⋅ 5 H 2O
d) 4.18 ×1024 molecules of C2 H 4 (OH) 2
e) a quantity of the amino acid lysine, C6 H14 N 2O 2 , containing 3.03 mol N atoms
2)
Determine the number of moles of
a) N atoms in a sample of C7 H 5 (NO 2 )3 that has the same number of O atoms as 12.4 g C6 H12O6
b) Br2 in a sample consisting of 2.17 ×1024 Br atoms
c) N atoms in 43.5 g of Mg(NO3 ) 2
d) Br2 in a sample consisting of 2.65 L liquid bromine (d = 3.10 g/mL)
3)
Explain which of the following statement(s) is (are) correct for sorbic acid, C6H8O2.
a) it has a C:H:O mass ratio of 3:4:1.
b) it has the same mass % composition as acrolein, C3H4O.
c) it has the same empirical formula as aspidinol, C12H16O4.
d) it has four times as many H atoms as O atoms, but four times as much O as H by mass.
4)
For the compound Ge[S(CH2)4CH3]4, determine
a) the total number of atoms in one formula unit
b) the ratio, by number, of C atoms to H atoms to 3 significant figures
c) the ratio, by mass, of Ge to S to 3 significant figures
d) the number of g S in 1 mol of the compound to 3 significant figures
e) the number of C atoms in 33.10 g of the compound
5)
Determine the mass % O in the mineral malachite, Cu 2 (OH) 2CO3 .
6)
Determine the mass % H2O in the hydrate Cr(NO3 )3 ⋅ 9H 2O . Express your answer to 4 significant figures.
7)
Determine the empirical formula of the rodenticide warfarin (a carbon-hydrogen-oxygen compound), which consists of 74.01% C and 20.76% O by mass.
8)
Selenium forms two oxides. One has 28.8% O by mass and the other has 37.8% O. What are the formulas of these two oxides?
9)
Adenine is a carbon-hydrogen-nitrogen compound with 44.45% C and 3.73% H by mass. It’s molecular mass is 135.14 u. What is its molecular formula?
10) Combustion of a 0.312 g sample of a carbon-hydrogen-nitrogen