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

2024
Views:

204

Pages:

4
Author:

era3s4ksd

1. How many atoms are there in each of the following? a) 5 molecules of C6H12Cl4 Answer: 5 molecules C6H12Cl4 * 12 atoms/molecule = 60 atoms b) 10 molecules of Co(ClO4)2 * 6H2O Answer: 10 molecules Co(ClO4)2 * 6H2O * 29 atoms/molecule = 290 atoms 2. How many molecules are there in each of the following? a) A flask containing 50.0 mL of NH3(g) at STP Answer: 50.0 mL NH3 * (1 L / 1000 mL) * (1 mol / 22.4 L) * (6.022 x 10^23 molecules / 1 mol) = 1.34 x 10^22 molecules NH3 b) 75.0 g of sugar (C12H22O11) Answer: 75.0 g C12H22O11 * (1 mol / 342.3 g) * (6.022 x 10^23 molecules / 1 mol) = 1.32 x 10^23 molecules C12H22O11 3. What is the volume occupied by each of the following gases at STP? a) 10.0 g of H2S (g) Answer: 10.0 g H2S * (1 mol / 34.08 g) * (22.4 L / 1 mol) = 6.58 L H2S b) 8.5 x 10^25 molecules of B2H6 (g) Answer: 8.5 x 10^25 molecules B2H6 * (1 mol / 6.022 x 10^23 molecules) * (22.4 L / 1 mol) = 3.2 x 10^2 L B2H6 4. What is the mass of each of the following? a) 1 atom of Au Answer: 1 atom Au * (1 mol / 6.022 x 10^23 atoms) * (196.97 g / 1 mol) = 3.271 x 10^-22 g Au b) 1.5 x 10^15 molecules of AgCl Answer: 1.5 x 10^15 molecules AgCl * (1 mol / 6.022 x 10^23 molecules) * (143.32 g / 1 mol) = 3.6 x 10^-7 g AgCl c) 250.0 mL of C3H8 (g) at STP Answer: 250.0 mL C3H8 * (1 L / 1000 mL) * (1 mol / 22.4 L) * (44.09 g / 1 mol) = 0.4695 g C3H8 5. How many moles are in each of the following? a) 5.00 g of C2H6 Answer: 5.00 g C2H6 * (1 mol / 30.07 g) = 0.0390 mol C2H6 b) 1.00 mL of O3 (g) at STP Answer: 1.00 mL O3 * (1 L / 1000 mL) * (1 mol / 22.4 L) = 4.46 x 10^-5 mol O3 c) 4.55 x 10^12 atoms Pt Answer: 4.55 x 10^12 atoms Pt * (1 mol / 6.022 x 10^23 atoms) = 7.56 x 10^-12 mol Pt d) 6.02 x 10^16 molecules of PCl5 Answer: 6.02 x 10^16 molecules PCl5 * (1 mol / 6.022 x 10^23 molecules) = 1.00 x 10^-7 mol PCl5 6. What is the molar mass of each of the following? a) A protein molecule having a mass of 1.25 x 10^-17 g Answer: 1.25 x 10^-17 g / 1 molecule * (6.022 x 10^23 molecules / 1 mol) = 7.53 x 10^6 g/mol protein b) 0.179 moles of a substance having a mass of 74.0 g Answer: 74.0 g / 0.179 mol = 413 g/mol substance c) Na2S2O3 * 5H2O Answer: (2 * 22.99) + (2 * 32.06) + (3 * 16.00) + (10 * 1.01) + (5 * 16.00) = 248.2 g/mol Na2S2O3 * 5H2O 7. a) What is the molar volume of gold? (density = 19.31 g/cm³) Answer: 19.31 g/cm³ * (1000 cm³ / 1 L) * (1 mol / 196.97 g) = 98.04 cm³/mol Au b) What is the density of liquid octane, C8H18, if 0.100 moles of octane has a volume of 16.2 mL? Answer: 0.100 mol C8H18 * (114.23 g / 1 mol) / 16.2 mL = 0.705 g/mL C8H18 c) What is the density of NOCl (g) at STP? Answer: 65.46 g/mol / 22.4 L/mol = 2.92 g/L NOCl