University:
Glendale Community College
Course:
CHM130 | Fundamental Chemistry
Academic year:

2019
Views:

488

Pages:

2
Author:

Maria Dunn

CHM130 CHAPTER 9 HOMEWORK KEY 1. Check all of the following that are equal to 1 mole: The following are all equal to 1 mole: 28.02 g N2, 153.81 g CCl4, 6.02x1023 CH4 molecules, 22.4 L HCl (g), and 119.00 g KBr. One mole of SO2 has a mass of 64.07 g, NOT 60.09 g; one mole of NO2 has a mass of 46.01 g, NOT 30.01 g; and one mole of I2 has a mass of 253.80 g, NOT 126.90 g. Also, only 1 mole of any gas occupies a volume of 22.4 L at STP, and 6.02x1023 of anything is equal to 1 mole. 2. The molar mass (MM) of CBr4 is _________ g/mol. MM of C + 4(MM of Br) = 12.01 + 4(79.90) = 331.61 g/mol 3. The molar mass (MM) of the CuCr2O7 is _________ g/mol. MM of Cu + 2(MM of Cr) + 7(MM of O) = 63.55 + 2(52.00) + 7(16.00) = 279.55 g/mol 4. The molar mass (MM) of the (NH4)2SO4 is _________ g/mol. 2(MM of N) + 8(MM of H) + MM of S + 4(MM of O) = 2(14.01) + 8(1.01) + 32.07 + 4(16.00) = 132.17 g/mol 5. The molar mass (MM) of Fe(C2H3O2)3 is _________ g/mol. MM of Fe + 6(MM of C) + 9(MM of H) + 6(MM of O) = 55.85 + 6(12.01) + 9(1.01) + 6(16.00) = 233.00 g/mol 6. What mass of NO2 is present in 3.00 moles of NO2? 46.01 g NO2 = 138 g NO2 3.00 moles NO2 x mol NO2 7. How many moles of CO are present in 175 g of CO? 175 g CO x mol CO = 6.25 moles CO 28.01 g CO 8. How many moles of HCl are present in 50.0 g of HCl? 50.0 g HCl x mol HCl = 1.37 moles HCl 36.46 g HCl 9. How many moles of NO(g) are present in 50.0 L of NO(g) at STP? 50.0 L NO x mol NO = 2.23 moles NO 22.4 L NO 10. How many moles of argon gas are present in 75.0 L of argon at STP? 75.0 L Ar x mol Ar = 3.35 moles Ar 22.4 L Ar 11. How many neon atoms are present in 25.0 g of neon? 25.0 g Ne x mol Ne 6.02x1023 Ne atoms = 7.46x1023 Ne atoms x 20.18 g Ne mol Ne 12. How many NH3 molecules are present in 65.0 g of NH3? 65.0 g NH3 x mol NH3 6.02x1023 NH3 molecules = 2.30x1024 NH3 molecules x 17.04 g NH3 mol NH3 13. What mass of HF(g) is present in 60.0L of HF(g)? 60.0 L HF x mol HF 20.01 g HF = 53.6 g HF x 22.4 L HF mol HF 14. What mass of He(g) is present in 25.0L of He(g)? 25.0 L He x mol He 4.00 g He = 4.46 g He x 22.4 L He mol He Page 1 of 2 CHM130 CHAPTER 9 HOMEWORK KEY 15. What mass of NO(g) is present in 55.0L of NO(g)? 55.0 L NO x mol NO 22.4 L NO x 30.01 g NO = 73.7 g NO mol NO 16. What volume (in L) of argon gas is present in 50.0 g of argon? 50.0 g Ar x mol Ar x 39.95 g Ar 22.4 L Ar = 28.0 L Ar mol Ar 17. What volume (in L) of CO gas is present in 105 g of CO(g)? 105 g CO x mol CO 22.4 L CO = 84.0 L CO x 28.01 g CO mol CO 18. Calculate the mass percentage of each element in CO2. One mole of CO2 (MM=44.01 g/mol) contains 12.01 g of carbon and 32.00 g of oxygen. 1(12.01 g C) x100% = 27.29% C C: 44.01 g CO2 2(16.00 g O) x100% = 72.71% O O: 44.01 g CO2 19. Calculate the mass percentage of each element in Na3P. One mole of Na3P (MM=99.94 g/mol) contains 68.97 g of sodium and 30.97 g of phosphorus. 3(22.99 g Na) x100% = 69.01% Na Na: 99.94 g Na3P 1(30.97 g P) x100% = 30.99% P P: 99.94 g Na3P 20. Calculate the mass percentage of each element in CaCrO4. One mole of CaCrO4 (MM=156.08 g/mol) contains 40.08 g of calcium, 52.00 g of chromium, and 64.00 g of oxygen. 1(40.08 g Ca) x100% = 25.68% Ca Ca: 156.08 g CaCrO4 1(52.00 g Cr) x100% = 33.32% Cr Cr: 156.08 g CaCrO4 4(16.00 g O) x100% = 41.00% O O: 156.08 g CaCrO4 Page 2 of 2