CHM142 Exam 1 Review with correct Solutions/Miami University
What is the total concentration of ions (in mol/L) in a solution obtained by dissolving 3.51 g of Cr(NO3)3 in enough water to make 351 mL of solution? (Molar mass of Cr(NO3)3: 238.01 g/mol) - Ans: 0.168 +/- 1% What is the concentration of sodium ions (in mol/L) in a solution obtained by mixing 90.5 mL of 0.181 M solution of Na2SO4 and 65.5 mL of 0.147 M solution of Na3PO4? Assume that volumes are additive. - Ans: 0.395 Which of the following molecules is polar? - Ans: IF5 What is the mole fraction of ethanol in a solution obtained by mixing 4.87 g of C2H5OH and 13.9 g of H2O? - Ans: 0.121 The solubility of argon in water at 0.474 atm gas pressure is 0.706 mmol/L. To what value (in atm) should the pressure of argon be increased for its concentration in water to reach the value of 1.35 mmol/L? - Ans: 0.906 What is the molarity (in mol/L) of solute B (molar mass = 112.85 g/mol) in solvent A (molar mass = 76.48 g/mol ) if 4.38 g of B are dissolved in 18.16 g of A? The density of solution is 1.068 g/mL. - Ans: 1.84 What is the molality of a solution of propanol in water in which the mole fraction of propanol is 0.175? - Ans: 11.77 Which of the following are colligative properties? A. vapor pressure B. freezing point depression C. boiling point - Ans: only B What should be the mole fraction of a nonvolatile solute in water to lower its vapor pressure by 4.78 torr at 30 ºC. At that temperature the vapor pressure of pure water is 31.82 torr. - Ans: 0.15 What is the mole fraction of benzene in the liquid phase of a mixture of benzene and toluene which at 20 ºC has the total vapor pressure equal to 56.7 torr? (At 20 ºC the vapor pressure of pure benzene is 75.0 torr, and the vapor pressure of pure toluene is 21.8 torr.) - Ans: 0.656 A 50.0 mL solution contains 0.142 g of KNO3. The osmotic pressure of this solution at 25.0 ºC was found to be 1.25 atm. What is the van't Hoff factor (i) for this solution? - Ans: 1.82 Consider the following reaction 5Br-(aq) + BrO3-(aq) + 6H+(aq) → 3Br2(aq) + 3H2O(l) Which one of the following is not a valid expression between various rates involving reactants and products?
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chm142 exam 1 review
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