Formula Calculation Problems

1.	Give the name of the following compounds: (a) Li2SO4, (b) CaCl2, (c) Na2HPO4.2H2O, (d) KHSO4, (e) PbF2, (f) NH4Br, (g) MnSO4.H2O
	Answer: (a) Lithium sulfate, (b) Calcium chloride, (c) Sodium hydrogen phosphate dihydrate, (d) Potassium hydrogen sulfate (e) Plumbous fluoride or Lead(II) fluoride (f) Ammonium bromide (g) Manganese sulfate monohydrate
2.	Give the formula of the following compounds: (a) Magnesium chloride, (b) Barium peroxodisulfate tetrahydrate, (c) Lithium hydroxide monohydrate, (d) Ammonium bromide, (e) Nickel chloride, (f) Lithium bromide, (g) Aluminum nitrate nonahydrate
	Answer: (a) MgCl2, (b) BaS2O8.4H2O, (c) LiOH.H2O, (d) NH4Br (e) NiCl2 (f) LiBr (g) Al(NO3)3.9H2O
3.	What is the formula weights of the following compounds: (a) CaC4H4O6.2H2O, (b) Na2S.9H2O, (c) NH4NO3, (d) Sr(NO3)2, (e) NH4SCN, (f) KCl, (g) CuS
	Answer: (a) 224.1824 g , (b) 240.17634 g, (c) 80.0432 g, (d) 211.6298 g, (e) 76.116 g, (f) 74.5513 g, (g) 95.606 g
4.	Calculate the number of moles of LiNO3 that will contain 6.02 x 1023 atoms of O.
	Answer: 0.33 mol LiNO3
5.	Calculate the number of moles of UO2(NO3)2 that will contain 6.02 x 1023 atoms of O.
	Answer: 0.125 mol UO2(NO3)2
6.	Calculate the number of moles of AlK(SO4)2.12H2O that will contain 6.02 x 1023 atoms of O.
	Answer: 0.05 mol AlK(SO4)2.12H2O
7.	How many number of Co atoms are contained in 43.3 g of CoSO4?
	Answer: 1.68 x 1023 Co atoms
8.	How many number of F atoms are contained in 7.81 g of BaF2?
	Answer: 5.36 x 1022 F atoms
9.	How many number of Cr atoms are contained in 63.75 g of Hg2CrO4?
	Answer: 7.42 x 1022 Cr atoms
10.	How many number of I atoms are contained in 2.54 g of Hg2I2?
	Answer: 4.67 x 1021 I atoms
11.	Determine the number of molecules of (NH4)2S present in 59.86 g of (NH4)2S.
	Answer: 5.29 x 1023 molecules
12.	Determine the number of molecules of Rb2SO4 present in 83.38 g of Rb2SO4.
	Answer: 1.88 x 1023 molecules
13.	Determine the number of molecules of NH4Br present in 12.3 g of NH4Br.
	Answer: 7.56 x 1022 molecules
14.	Calculate the weight in grams of 2.62 mol Cd(NO3)2.4H2O.
	Answer: 808.22 g
15.	Calculate the weight in grams of 0.92 mol NH4NO3.
	Answer: 73.64 g
16.	Calculate the weight in grams of 3.8 mol NaCH3COO.
	Answer: 311.73 g
17.	Determine the mass of 8.04 x 10-9 mol of CaCl2. Calculate the number of Ca atoms in 8.04 x 10-9 mol of CaCl2.
	Answer: 8.92 x 10-7 g; 4.84 x 1015 atoms
18.	Determine the mass of 10 x 10-3 mol of MgSO4.7H2O. Calculate the number of O atoms in 10 x 10-3 mol of MgSO4.7H2O.
	Answer: 2.46 g; 6.62 x 1022 atoms
19.	Determine the mass of 9.27 x 10-8 mol of KNO3. Calculate the number of O atoms in 9.27 x 10-8 mol of KNO3.
	Answer: 9.37 x 10-6 g; 1.67 x 1017 atoms
20.	How many grams of each of the constituent elements are contained in 1 mol of: (a) LiI, (b) Li2SO4.H2O, (c) Rb2SO4, (d) CaC4H4O6.2H2O, (e) CsCl, (f) CoSO4, (g) Ba(NO3)2.H2O
	Answer: (a) 1 mol Li = 6.941 g Li, 1 mol I = 126.9045 g I; (b) 2 mol H = 2.0158 g H, 5 mol O = 79.997 g O, 2 mol Li = 13.882 g Li, 1 mol S = 32.06 g S; (c) 2 mol Rb = 170.9356 g Rb, 1 mol S = 32.06 g S, 4 mol O = 63.9976 g O; (d) 8 mol H = 8.0632 g H, 8 mol O = 127.9952 g O, 1 mol Ca = 40.08 g Ca, 4 mol C = 48.044 g C; (e) 1 mol Cs = 132.9054 g Cs, 1 mol Cl = 35.453 g Cl; (f) 1 mol Co = 58.9332 g Co, 1 mol S = 32.06 g S, 4 mol O = 63.9976 g O; (g) 2 mol H = 2.0158 g H, 7 mol O = 111.9958 g O, 1 mol Ba = 137.33 g Ba, 2 mol N = 28.0134 g N
21.	Calculate the number of moles in 8.25 g CuCl2.
	Answer: 0.06 mol CuCl2
22.	Calculate the number of moles in 46.24 g NaH2PO4.
	Answer: 0.39 mol NaH2PO4
23.	Calculate the number of moles in 48.82 g Sr(NO3)2.
	Answer: 0.23 mol Sr(NO3)2
24.	Determine the number of moles in 3.49 g of Be.
	Answer: 0.39 mol Be
25.	Determine the number of moles in 68.94 g of O.
	Answer: 4.31 mol O
26.	Determine the number of moles in 98.05 g of Si.
	Answer: 3.49 mol Si
27.	Calculate the weight of one molecule of (a) Hg2CrO4, (b) FeSO4.7H2O, (c) ZnSO4.H2O, (d) Cu(OH)2, (e) MgCl2.6H2O, (f) Cu(NO3)2, (g) Al(OH)3
	Answer: (a) 8.59 x 10-22 g/molecule, (b) 4.62 x 10-22 g/molecule, (c) 2.98 x 10-22 g/molecule, (d) 1.62 x 10-22 g/molecule, (e) 3.38 x 10-22 g/molecule, (f) 3.12 x 10-22 g/molecule, (g) 1.3 x 10-22 g/molecule
28.	How much BaCO3 can be produced from 62.98 g of O?
	Answer: 258.94 g BaCO3
29.	How much MnS can be produced from 68.56 g of Mn?
	Answer: 108.57 g MnS
30.	How much Al(OH)3 can be produced from 62.1 g of Al?
	Answer: 179.53 g Al(OH)3

Isotope Problems

1.	Silver atom has two known isotopes existing in nature as 51.82 % 107Ag (atomic mass: 106.9041 u) and 48.18 % 109Ag (atomic mass: 108.9047 u) Calculate the atomic weight of Silver.
	Answer: 107.868 u
2.	There are two known isotopes of Iridium atom: 191Ir with a mass of 190.9609 u and 193Ir which has a mass of 192.9633 u. The atomic weight of Iridium atom is 192.2164. What is the percentage occurrence in nature of 191Ir? What is the percentage occurrence in nature of 193Ir?
	Answer: 37.3% of 191Ir and 62.7% of 193Ir.
3.	Carbon has an atomic weight of 12.011. Its isotopes exist in nature in the following proportions: 98.89% of 12C, 1.11% of 13C. One of its isotope, 12C, has a mass of 12 u. What is the mass of the other isotope?
	Answer: 12.991 u

Here is a new set of chemistry problems that you can use as drill and/or reviewer questions.

Percent Composition Problems

1.	Cd(NO3)2.4H2O
	Answer: H = 2.61% O = 51.87% Cd = 36.44% N = 9.08%
2.	NaHCO3
	Answer: Na = 27.37% H = 1.2% C = 14.3% O = 57.14%
3.	Co(NO3)2
	Answer: Co = 32.21% N = 15.31% O = 52.47%
4.	A laboratory sample was found to contain 68.05 % BaCO3. Compute the amount of C present in 0.67 g of the sample.
	Answer: 0.03 g
5.	A laboratory sample was found to contain 33.56 % KIO3. Compute the amount of I present in 9.91 g of the sample.
	Answer: 1.97 g
6.	A laboratory sample was found to contain 44.72 % PbSO4. Compute the amount of O present in 1.56 g of the sample.
	Answer: 0.15 g
7.	A sample mixture containing ZnCl2 has 4.83 % Zn. Calculate the percentage of ZnCl2 in the sample.
	Answer: 10.07 %
8.	A sample mixture containing CuCO3 has 5.19 % C. Calculate the percentage of CuCO3 in the sample.
	Answer: 53.39 %
9.	Calculate the amount in g of C contained in 5.01 g of CaC4H4O6.
	Answer: 1.28 g of C
10.	Calculate the amount in g of Na contained in 7.43 g of Na2CO3.H2O.
	Answer: 2.75 g of Na

Solute Concentration Problems

1.	Calculate the weight of a 17% by weight CaCl2 solution that will contain 7.61 g CaCl2.
	Answer: 44.76 g solution
2.	Fuming hydrochloric acid has a density of 1.19 g/mL and has 37% HCl by weight. What is the mass of HCl in 55 mL of this acid?
	Answer: 24.22 g HCl
3.	4.69 g of HCl is needed to be obtained from fuming hydrochloric acid (density 1.19 g/mL) which has 37% HCl by weight. Calculate the volume of fuming hydrochloric acid needed.
	Answer: 10.65 mL fuming hydrochloric acid
4.	235 mL of a solution with a concentration of 8 M NaClO4 is needed to be diluted in order to prepare a solution having a concentration of 4 M NaClO4. What must be the final volume of the diluted solution?
	Answer: 470 mL
5.	How many g of ZnCl2 is needed to prepare a 182 mL of a solution containing 3.46 g ZnCl2 per mL?
	Answer: 629.72 g ZnCl2
6.	Calculate the weight of a 8% by weight KI solution that will contain 3.46 g KI.
	Answer: 43.25 g solution
7.	Concentrated sulfuric acid has a density of 1.84 g/mL and has 97% H2SO4 by weight. What is the mass of H2SO4 in 144 mL of this acid?
	Answer: 257.01 g H2SO4
8.	137 mL of a solution with a concentration of 5 M Cu2S is needed to be diluted in order to prepare a solution having a concentration of 1 M Cu2S. What must be the final volume of the diluted solution?
	Answer: 685 mL
9.	4.69 g of HCl is needed to be obtained from fuming hydrochloric acid (density 1.19 g/mL) which has 37% HCl by weight. Calculate the volume of fuming hydrochloric acid needed.
	Answer: 10.65 mL fuming hydrochloric acid
10.	101 mL of a solution with a concentration of 8.24 g K2S2O5 per mL is needed to be diluted in order to prepare a solution having a concentration of 6.45 g K2S2O5 per mL. What must be the final volume of the diluted solution?
	Answer: 129.03 mL

Stoichiometry Problems

1.	Based on the following equation: Cu2S + O2 --> 2Cu + SO2, calculate the number of mol of Cu2S required to yield 4.02 mol of Cu.
	Answer: 2.01 mol of Cu2S
2.	Given the equation: 2KClO3 --> 2KCl + 3O2, how many mol of KClO3 will be needed to produce 7.23 mol of O2?
	Answer: 4.82 mol of KClO3
3.	According to the equation: CaCO3 --> CaO + CO2, calculate the mass of CaCO3 required so that 4.29 mol of CaO will be produced.
	Answer: 429.38 g of CaCO3
4.	Based on the following equation: 2C2H6 + 7O2 --> 4CO2 + 6H2O, how many g of C2H6 will be needed to produce 4.87 mol of H2O?
	Answer: 48.81 g of C2H6
5.	Based on the following equation: CaO + 3C --> CaC2 + CO, how many g of C is required so that 1.2 g of CaC2 is produced?
	Answer: 0.67 g of C
6.	Given the equation: 4KClO3 --> 3KClO4 + KCl, calculate the weight of KClO3 necessary to produce 8.37 g of KClO4.
	Answer: 9.87 g of KClO3
7.	Given the equation: 2KClO3 --> 2KCl + 3O2, calculate the amount of O2 that can be produced from the decomposition of 7.83 g of KClO3.
	Answer: 3.07 g of O2
8.	According to the equation: 4KClO3 --> 3KClO4 + KCl, calculate the weight of KClO3 necessary to produce 2.86 g of KCl.
	Answer: 18.81 g of KClO3
9.	Based on the following equation: 5C + 2SO2 --> CS2 + 4CO, how many g of C will be needed to produce 3.07 mol of CO?
	Answer: 46.09 g of C
10.	Based on the following equation: CaCO3 + 2HCl --> CO2 + CaCl2 + H2O, how many mol of CaCO3 is needed to produce 1.57 g of CO2?
	Answer: 0.04 mol of CaCO3