Chapter 7.1: The Mole
1 mole of something always contains how many particles? What is this number called?
6.022 x 1023 particles, Avogadro’s number
The quantity of grams that equals one mole of an element is called __________ and can be found where?
molar mass, the atomic mass on the periodic table
Calculate the mass, in grams, for each of the following:
a. 1.50 mol of Na
b. 2.80 mol of Ca
c. 0.125 mol of CO2
d. 0.0485 mol of Na2CO3
e. 7.14 x 102 mol of PCl3
a. 34.5 g
b. 112 g
c. 5.50 g
d. 5.14 g
e. 9.80 x 104 g
The percent of an element within a known amount of a compound is called
mass percent composition or mass percent
The actual formula of a compound is called:
the molecular formula
Write the empirical formula for each of the following substances:
a. H2O2, peroxide
b. C18H12, chrysene, used in the manufacture of dyes
c. C10H16O2, chrysanthemic acid, in pyrethrum flowers
d. C9H18N6, altretamine, anticancer medication
e. C2H4N2O2, oxamide, fertilizer
a. HO
b. C3H2
c. C5H8O
d. C3H6N2
e. CH2NO
Calculate each of the following:
a. Number of C atoms in 0.500 mol of C
b. Number of SO2 molecules in 1.28 mol of SO2
c. Moles of Fe in 5.22 x1022atoms of Fe
d. Moles of C2H6O in 8.50 x 1024 molecules of C2H6O
a. 3.01 x 1023 atoms of C
b. 7.71 x 1023 molecules of SO2
c. 0.0867 mol of Fe
d. 14.1 mol of C2H6O
Calculate the molar mass for each of the following:
a. Cl2
b. C3H6O3
c. Mg3(PO4)2
a. 70.90 g
b. 90.08 g
c. 262.9 g
Calculate the mass, in grams, in 0.150 mol of each of the following:
a. Ne
b. I2
c. Na2O
d. Ca(NO3)2
e. C6H14
a. 3.03 g
b. 38.1 g
c. 9.30 g
d. 24.6 g
e. 12.9 g
What is the formula for mass percent composition?
Mass of element/total mass of compound x 100%
The formula that represents the lowest whole-number ration of the atoms in a compound is called:
the empirical formula
The carbohydrate fructose found in honey and fruits has an empirical formula of CH2O. If the experimental molar mass of fructose is 180 g, what is its molecular formula?
C6H12O6
Calculate each of the following quantities in 2.00 mol of H3PO4:
a. Moles of H
b. Moles of O
c. Atoms of P
d. Atoms of O
a. 6.00 mol of H
b. 8.00 mol of O
c. 1.20 x 1024 atoms of P
d. 4.82 x 1024 atoms of O
Calculate the molar mass for each of the following:
a. AlF3
b. C2H4Cl2
c. SnF2
a. 83.98 g
b. 98.95 g
c. 156.7 g
Calculate the number of moles in each of the following:
a. 82.0 g of Ag
b. 0.288 g of C
c. 15.0 g of ammonia, NH3
d. 7.25 g of CH4
e. 245 g of Fe2O3
a. 0.760 mol of Ag
b. 0.0240 mol of C
c. 0.881 mol of NH3
d. 0.452 mol of CH4
e. 1.53 mol of Fe2O3
Calculate the mass percent composition of each of the following:
a. 4.68 g of Si and 5.32 g of O
b. 5.72 g of C and 1.28 g of H
c. 16.1 of Na, 22.5 g of S, and 11.3 g of O
d. 6.22 g of C, 1.04 g of H, and 4.14 g of O
a. 46.8% Si; 53.2% O
b. 81.7% C; 18.3% H
c. 32.3% Na; 45.1% S; 22.6% O
d. 54.6% C; 9.12% H; 36.3% O
Calculate the empirical formula for each of the following:
a. 3.57 g of N and 2.04 g of O
b. 7.00 g of C and 1.75 g of H
c. 0.175 g of H, 2.44 g of N, and 8.38 g of O
d. 2.06 g of Ca, 2.66 g of Cr, and 3.28 g of O
a. N2O
b. CH3
c. HNO3
d. CaCrO4
Benzene and acetylene have the same empirical formula, CH. However, benzene has an experimental molar mass of 78 g, and acetylene has an experimental molar mass of 26 g. What are the molecular formulas of benzene and acetylene?
benzene C6H6; acetylene C2H2
Quinine, C20H24N2O2, is a component of tonic water and bitter lemon.
a. How many moles of H are in 1.5 mol of quinine?
b. How many moles of C are in 5.0 mol of quinine?
c. How many moles of N are in 0.020 mol of quinine?
a. 36 mol of H
b. 1.0 x 102 mol of C
c. 0.040 mol of N
Calculate the molar mass for each of the following:
a. KCl, salt substitute
b. Fe2O3, rust
c. C19H20FNO3, Paxil, antidepressent
a. 74.55 g
b. 159.7 g
c. 329.4 g
Calculate the number of moles in 25.0 g of each of the following:
a. He
b. O2
c. Al(OH)3
d. Ga2S3
e. C4H10, butane
a. 6.25 mol of He
b. 0.781 mol of O2
c. 0.321 mol of Al(OH)3
d. 0.106 mol of Ga2S3
e. 0.430 mol of C4H10
Calculate the mass percent composition of each of the following:
a. MgF2, magnesium fluoride
b. Ca(OH)2, calcium hydroxide
c. C4H8O4, erythrose, a carbohydrate
d. (NH4)3PO4, ammonium phosphate, fertilizer
e. C17H19NO3, morphine, a painkiller
a. 39.01% Mg; 60.99% F
b. 54.09% Ca; 43.18% O; 2.721% H
c. 40.00% C; 6.714% H; 53.29% O
d. 28.19% N; 8.115% H; 20.77% P; 42.92% O
e. 71.55% C; 6.710% H; 4.909% N; 16.82% O
Calculate the empirical formula for each of the following:
a. 70.9% K and 29.1% S
b. 55.0% Ga and 45.0% F
c. 69.6% Mn and 30.4% O
d. 18.8% Li, 16.3% C, and 64.9% O
e. 51.7% C, 6.95% H, and 41.3% O
a. K2S
b. GaF3
c. Mn2O3
d. Li2CO3
e. C5H8O3
A sample of nicotine, a poisonous compound found in tobacco leaves, contains 74.0% C, 8.70% H, and 17.3% N. If the experimental molar mass of nicotine is 162 g, what is its molecular formulas?
C10H14N2
Naproxen is used to treat pain and inflammation caused by arthritis. Naproxen has a formula of C14H14O3.
a. How many moles of C are present in 2.30 mol of naproxen?
b. How many moles of H are present in 0.444 mol of naproxen?
c. How many moles of O are present in 0.0765 mol of naproxen?
a. 32.2 mol of C
b. 6.22 mol of H
c. 0.230 mol of O
Calculate the molar mass for each of the following:
a. Al2(SO4)3, antiperspirant
b. KC4H5O6, cream of tartar
c. C16H19N3O5S, amoxicillin, antibiotic
a. 342.2 g
b. 188.18 g
c. 365.5 g
Dinitrogen oxide (of nitrous oxide), N2O, also known as laughing gas, is widely used as an anesthetic in dentistry.
a. How many grams of the compound are in 1.50 mol of dinitrogen oxide?
b. How many moles of the compound are in 34.0 g of dinitrogen oxide?
c. How many grams of N are in 34.0 g of dinitrogen oxide?
a. 66.0 g of N2O
b. 0.772 mol of N2O
c. 21.6 g of N
Calculate the mass percent of N in each of the following:
a. N2O5, dinitrogen pentoxide
b. NH4Cl, expectorant in cough medicine
c. C2H8N2, dimethylhydrazine, rocket fuel
d. C9H15N5O, Rogaine, stimulates hair growth
e. C14H22N2O, lidocaine, local anesthetic
a. 25.94% N
b. 26.19% N
c. 46.62% N
d. 33.47% N
e. 11.96% N
Ascorbic acid (vitamin C), found in citrus fruits and vegetables, is important in metabolic reactions in the body, in the synthesis of collagen, and in the prevention of scurvy. If the mass percent composition of ascorbic acid is 40.9% C, 4.58% H, and 54.5% O, what is the empirical formula of ascorbic acid?
C3H4O3
Clavulanic acid has a molecular formula of C8H9NO5.
a. What is the molar mass of clavulanic acid?
b. What is the mass percent of C in clavulanic acid?
c. Max weighs 12 kg. If the dose of clavulanic acid is 2.5 mg/kg, how many moles of clavulanic acid are given?
a. 199.16 g
b. 48.24% C
c. 1.5 x 10-4mol