University:
Campbell University
Course:
CHEM 111 | General Chemistry I
Academic year:

2021
Views:

114

Pages:

2
Author:

santjinlmr

KEY The Mole Name - ______________ 1.) You obtain the following results. 11.1 ݃ of hydrogen gas reacts with 88.9 ݃ of oxygen gas. 46.7 ݃ of nitrogen gas react with 53.3 ݃ of oxygen gas. 42.9 ݃ of carbon react with 57.1 ݃ of oxygen gas. Assuming a mass of “1” for hydrogen, calculate the relative mass of oxygen, nitrogen and carbon. (Don’t be surprised if the values you calculate are not what you expect. Not all molecules involve 1:1 ratios, which was a problem for early chemists too). Answer – Convert mass of hydrogen to being “1”. ‫=ܪ‬ Convert all elements relative to hydrogen. ܰ= ସ଺.଻ ହଷ.ଷ = 0.876 × 8.01 = 7.01 ‫=ܥ‬ ܱ= ସଶ.ଽ ହ଻.ଵ ଵଵ.ଵ ଵଵ.ଵ ଼଼.ଽ ଵଵ.ଵ =1 = 8.01 = 0.751 × 8.01 = 6.02 2.) If 1.0 ‫ ܮ‬of nitrogen gas reacts with 3.0 ‫ ܮ‬of chlorine gas when both gases are at the same temperature and pressure, how many chlorine molecules are present for every nitrogen molecule in the reaction? Suggest a formula for the compound formed and name the compound. Answers - 3 chlorine for every 1 nitrogen NCl3 = nitrogen trichloride 3.) Experimentally it is found that 1.5 ‫ ܮ‬of gaseous sulphur reacts with 3.0 ‫ ܮ‬of gaseous oxygen at the same temperature and pressure. Suggest a possible formula and name the compound formed. Answers - There is double oxygen to sulphur. SO2 = sulphur dioxide 4.) At room temperature and pressure, 250 ݉‫ ܮ‬of chlorine gas react completely with 750 ݉‫ ܮ‬of fluorine gas. Suggest a possible formula and name for the compound formed in the reaction. Answers - There is triple the amount of fluorine to chlorine. ClF3 = chlorine trifluoride 1 KEY 5.) If 1.0 ‫ ܮ‬of unknown gas X contains 3.0 × 10 ଶଷ ݉‫ ݏ݈݁ݑ݈ܿ݁݋‬at a certain temperature and pressure, how many molecules are present in 5.0 ‫ ܮ‬of oxygen gas at the same temperature and pressure? Answer - 5.0 ‫× ܮ‬ ଷ.଴ ×ଵ଴మయ ௠௢௟௘௖ ଵ.଴ ௅ = 1.5 × 10ଶସ ݉‫ݏ݈݁ݑ݈ܿ݁݋‬ 6.) Calculate the molar mass of each of the following. a.) NO ሺ1 × 14.01ሻ + ሺ1 × 16.00ሻ = 30.01 ݃ i.) FeCl3 b.) H2O ሺ2 × 1.01ሻ + ሺ1 × 16.00ሻ = 18.02 ݃ j.) SnC2O4 ሺ1 × 118.71ሻ + ሺ2 × 12.01ሻ + ሺ4 × 16.00ሻ = 206.73 ݃ c.) NH3 ሺ1 × 14.01ሻ + ሺ3 × 1.01ሻ = 17.04 ݃ k.) Sn(C2O4)2ሺ1 × 118.71ሻ + ሺ4 × 12.01ሻ + ሺ8 × 16.00ሻ = 294.75 ݃ d.) CO2 ሺ1 × 12.01ሻ + ሺ2 × 16.00ሻ = 44.01 ݃ l.) (NH4)3PO4 149.12 ݃ e.) CH4 ሺ1 × 12.01ሻ + ሺ4 × 1.01ሻ = 16.05 ݃ m.) CH3COOH 60.06 ݃ f.) AgNO3 ሺ1 × 107.87ሻ + ሺ1 × 14.01ሻ + ሺ3 × 16.00ሻ = 169.88 ݃ n.) CH3CH2CH2CH3 58.14 ݃ g.) Ca(OH)2ሺ1 × 40.08ሻ + ሺ2 × 16.00ሻ + ሺ2 × 1.01ሻ = 74.10 ݃ o.) Ni(H2O)2(NH3)4Cl2 233.79 ݃ h.) Al(NO3)3ሺ1 × 26.98ሻ + ሺ3 × 14.01ሻ + ሺ9 × 16.00ሻ = 213.0 ݃ p.) Al2(SO4)3 ሺ1 × 55.85ሻ + ሺ3 × 35.45ሻ = 162.2 ݃ 342.1 ݃ 7.) Calculate the molar mass of each of the following. a.) Co3(AsO4)2 • 8H2O Answer - ሺ3 × 58.93ሻ + ሺ2 × 74.92ሻ + ሺ8 × 16.00ሻ + ሺ16 × 1.01ሻ + ሺ8 × 16.00ሻ = 598.8 ݃ b.) Pb(C2H3O2)2 • 3H2O Answer - ሺ1 × 207.20ሻ + ሺ4 × 12.01ሻ + ሺ6 × 1.01ሻ + ሺ4 × 16.00ሻ + ሺ6 × 1.01ሻ + ሺ3 × 16.00ሻ = 379.4 ݃ c.) MgSO4 • 7H2O Answer - ሺ1 × 24.31ሻ + ሺ1 × 32.06ሻ + ሺ4 × 16.00ሻ + ሺ14 × 1.01ሻ + ሺ7 × 16.00ሻ = 246.5 ݃ d.) KAl(SO4)2 • 12H2O Answer - ሺ1 × 39.01ሻ + ሺ1 × 26.98ሻ + ሺ2 × 32.06ሻ + ሺ8 × 16.00ሻ + ሺ24 × 1.01ሻ + ሺ12 × 16.00ሻ = 474.4 ݃ 2