INTRO TO THE MOLE -PART 1

Transcription

1 INTRO TO THE MOLE -PART 1 Multiple Choice Identify the letter of the choice that best completes the statement or answers the question. 1. The law of definite proportions states that Specific substances always contain elements in the same ratio by mass. Specific substances always contain elements in the same ratio by volum Equal volumes of gases, under the same conditions, have the same number of molecules. Specific substances always contain elements in the same ratio by atomic structur none of the above 2. Tin and oxygen can combine to form two compounds of different combining proportions. Resulting formulas of these compounds include Sn2O and SnO2 SnO and SnO3 and SnO and SnO2 SnO2 SnO4 SnO 4 and SnO 3. Gold and fluorine are able to combine to form two compounds of different combining proportions. Resulting formulas of these compounds include AuF 3 and AuF2 AuF and AuF3 Au3F and AuF AuF and AuF2 Au2F and AuF3 4. The ratio of hydrogen to oxygen, by mass, in water is 2:1 1:8 1:2 16:1 1:16 5. Which of the following best describes one mole of potassium sulfate, K SO? 2 4 It contains six atoms in total. It contains molecules. It contains one sulfur atom. none of the above It has a mass of g. 6. The molar mass of copper(ii) sulfate pentahydrate, CuSO 4.5H2O, is 5.6 g/mol 1.5 g/mol g/mol 9.6 g/mol g/mol 7. The number of moles of H in three moles of copper(ii) sulfate pentahydrate, CuSO 4.5H2O, is There are atoms present in 0.5 mol of C none of the above 0.5 mol of Na all of the above 0.5 mol of Ar 9. The number of carbon atoms present in mol of acetic acid, CH3COOH, is atoms atoms atoms atoms atoms 10. The number of molecules of hydrogen peroxide found in 3.15 mol of H2O 2 is

2 3 molecules molecules molecules molecules molecules 11. The number of hydrogen atoms present in mol of ammonia, NH 3, is atoms atoms atoms atoms atoms 12. The molar mass of a sample of atoms of an element was found to be g/mol. This element is likely silver oxygen copper lead magnesium 13. If the molar mass of an unknown substance is found to be 98.2 g/mol, determine the mass of 6.3 mol of the substanc 15.6 g g g g g 14. The number of moles of molecules in 71.6 g of methane, CH 4, (molar mass = 16.0 g/mol) is 0.22 mol 9.77 mol 4.48 mol 1145 mol 8.77 mol 15. The number of atoms represented by the formula Ca(NO 3) The total number of atoms in 3.75 mol of ammonium nitrate, NH4NO 3, is atoms atoms atoms atoms atoms 17. A mass of 2.20 kg of sodium phosphate is converted into the following number of moles 7.45 mol 13.4 mol 74.5 mol 45.8 mol mol 18. The mass found in 0.10 mol of KHC4H4O 6 is 4.6 g 37.6 g 19 g 55.8 g.7 g 19. A patient takes two 50.0-mg tablets on a daily basis to help regulate a heart condition. If the daily dosage 4 is equivalent to moles, then its molar mass is 200 g/mol 50 g/mol 100 g/mol 800 g/mol 400 g/mol Converting mol of ammonium hydroxide (NH4OH) into mass yields 0.6 g 1.7 g 1.0 g 2.2 g 1.3 g 21. The number of hydrogen atoms present in mol of octane, C H, is 8 18

3 atoms atoms atoms atoms atoms 22. The number of molecules found in 0.87 mol of carbon monoxide is molecules molecules molecules molecules molecules. A sample of 28.0 g of iron has approximately the same number of atoms as 2.0 g of He 39.0 g of K 31.0 g of P 64.0 g of Cu 6.0 g of Sn. The number of atoms of oxygen found in g of calcium phosphate, Ca 3(PO 4) 2, is approximately atoms atoms atoms atoms atoms. Converting g of Mg(CN) 2 into moles yields approximately 0.98 mol 3.06 mol 1.49 mol 2.00 mol 2.53 mol 26. The total number of atoms represented in the formula Be(C2H3O 2) 2 is A possible molecular formula for the compound CH2O is C2H4O2 C10H20O10 C3H6O3 all of the above C4H8O4 28. The percentage of nitrogen, by mass, in nitric acid, HNO 3, is 1.6% 22.2% 11.1% 72.6% 15.6% 29. The percentage of oxygen, by mass, in calcium hydrogen carbonate, Ca(HCO 3) 2, is.7% 1.2% 59.2% 68.2% 14.8% 30. The percentage of nitrogen, by mass, in copper(ii) nitrate, Cu(NO 3) 2, is 14.9% 40.2% 33.9% 45.1% 36.5% 31. The percentage composition of chlorine, by mass, in the compound K2PtCl 4 is 47.0% 15.3% 34.2% 11.3% 18.9% 32. The percentage composition by mass of each element in sodium sulphate, Na2SO 4, is 32.4% Na, 22.6% S, 45.0% O 20.7% Na, 43.7% S, 35.6% O 22.6% Na, 32.4% S, 45.0% O 35.0%Na, 20.0% S, 45.0% O 43.7% Na, 20.7% S, 35.6% O

4 33. Ammonium nitrate, NH4NO 3, is commonly used for fertilizer. The percentage of nitrogen, by mass, in this fertilizer is 17.5% 47.5% 22.5% 55.0% 35.0% 34. Which of the following is a candidate for an empirical formula? CH44O22 C4H8 N2O4 Na4S2O8 CH3OH 35. A g sample of a compound is made up of 35.9 g of aluminum and 64.1 g of sulfur. The empirical formula of the compound is Al2S3 Al3S2 Al4S6 Al6S4 AlS 36. A g sample of a compound is composed of 16.3 g of carbon, 32.1 g of chlorine, and 51.6 g of fluorin The empirical formula of the compound is CClF C3Cl2F6 Cl CClF3 C9 6F18 C2Cl2F6 37. A compound containing carbon, hydrogen, and chlorine is composed of 49.0% carbon and 2.74% hydrogen by mass; the remainder is chlorin The empirical formula of the compound is CHCl C2H3Cl C3H2Cl C2H3Cl2 C2H2Cl 38. The empirical formula of a compound containing 92.3% carbon and 7.7% hydrogen, by mass, is C20H20 CH4 C12H12 CH C6H6 39. A g sample of a compound contains 26.6 g of potassium, 35.4 g of chromium, and 38.0 g of oxygen. The empirical formula of the compound is K2Cr2O7 K3Cr3O10 KCrO5 KCrO7 KCrO Upon analysis in the lab, a compound is found to consist of 2.2% hydrogen, 26.7% carbon, and 71.1% oxygen. The empirical formula for this compound is H2C2O4 HCO2 HCO HC2O2 HC2O 41. Hydrogen peroxide is known to contain 5.9% hydrogen and 94.1% oxygen, by mass. If its molar mass is 34.0 g/mol, its molecular formula is HO HO 3 H2O2 H3O3 HO A compound with a molar mass of 78.0 g/mol is found to contain 92.29% carbon and 7.71% hydrogen, by mass. The molecular formula of the compound is CH C5H5 C2H3 C6H6 C H 3 3

5 43. A compound has a molar mass of g/mol and an empirical formula of SiF 3. The compound's molecular formula is SiF3 Si4F12 Si5F15 Si3F9 Si2F6 44. The molar mass of a compound is found experimentally to be g/mol. If its empirical formula is CH2O, its molecular formula will be C6H12O6 C3H6O3 C5H10O5 C2H4O2 C4H8O4 45. A compound was found to contain 10.06% carbon, 89.10% chlorine, and 0.84% hydrogen, by mass. If the molar mass of the compound was found to be g/mol, its molecular formula will be CHCl3 C3H3Cl3 CH3Cl C3HCl CH3Cl3 46. A g sample of an organic compound is made up of g of carbon, 6.71 g of hydrogen, and g of oxygen. If its molar mass is 90.0 g/mol, its molecular formula will be CH2O C7H14O7 C3H6O3 C5H10O5 C2H4O2 47. A compound consists of 49.0% carbon, 2.72% hydrogen, and 48.3% chlorine, by mass. A lab analysis shows that the compound has a molar mass of g/mol. The molecular formula of the compound is C3H2Cl C6H4Cl2 C9H6Cl3 C6H4Cl C9H3Cl3 48. If the molar mass of a hydrocarbon is 26.0 g/mol, and its empirical formula is CH, its molecular formula is CH C4H4 C2H2 C5H5 C3H3 49. Identify the career where it is important to be able to analyze unknown substances and determine the chemical content of these substances. forensic lab technician water purification technician gemologist metallurgy technician all of the above

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