Ans_Ex3 - Nielsen CHM1041 Answer Key Set 3 1. What is the...

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Nielsen Bhaskar/PC/1713Q/K 3/05 1 CHM1041 Answer Key Set 3 1. What is the percent sucrose (cane sugar), by weight, in a syrup prepared by dissolving 756 g sucrose in 1.20 kg water? 0 0 mass sucrose 0.756 sucrose = 100 100 38.6% total moss ratio 0.76 1.20 kg kg kg ×= + 2. The solubility of KNO 33 2 in water at 20°C is 31.6g KNO per 100 ml H O. The m l Density of water at What is the per cent by weight, in 20 is 0.998 / . Cg ° 3 KNO , The saturated solution? 22 0 0 3 100 0.998 / 99.8 31.6 100 24.0% 99.8 31.6 ml H O g ml g H O g KNO gg = + 3. A solution is prepared by mixing the following numbers of moles of hydrocarbons: 71 6 81 8 92 0 1.28 mole C H , 1.80 mole C H and 2.16 mole C H . What is (a) the mole Fraction and (b) the mole per cent of each component in this solution? () 8 0 7 16 6 8 0 a 1.28 0.244 1.28 1.80 2.16 1.80 0.344 1.28 1.80 2.16 2.16 1.28 1.80 2.16 CH moles C H X total moles mole mole mole moles C H moles X total moles moles mole mole moles C H moles X total moles moles mole moles == = ++ = 0.412 = 6 8 0 7 0 0 16 0 0 8 0 0 0 0 0 b Mole per cent = mole fraction × 100 , 100 0.244 100 24.4 , 100 0.344 100 34.4 , 100 0.412 100 41.1 100.0 X X X ×= ×=
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Nielsen Bhaskar/PC/1713Q/K 3/05 2 4. Calculate the mole fractions of ethyl alcohol, and water in a solution made by dissolving 9.20 of the alcohol in 18.0 of water. 25 C H OH, g g 5 2 2 2 1 - 9.20 0.200 46.1 1 18.0 1.00 18.0 0.200 0.167 0.200 1.00 1.00 0.833 0.200 1.00 CHOH HO mole moles C H OH g mole g mole moles H O g mole g mole X mole mole mole X mole mole =× = = == + + 5. a) Calculate the molality of a solution made by dissolving of ethylene 262 g glycol, 262 C H O , in 8000.g of water. 1 262 4.22 62.06 4.22 0.528 8.000 0.528 mole moles C H O g mole g moles solute mole mole molality or Kg solvent Kg Kg m = = = b) What is the molatily of P-dichlorobenzene in a solution prepared by dissolving 64 2 66 5.50 g C H Cl in 65.0 g benzene, C H ? 1 5.50 0.0374 147 0.0374 0.575 0.575 0.0650 mole moles C H Cl g mole g mole mole molality m Kg Kg ===
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Nielsen Bhaskar/PC/1713Q/K 3/05 3 c) What is the molality of a solution obtained by dissolving 15.2 The density of ethanol at g urea, () 2 2 CO NH , in 100.0 ml ethanol at 20°C? 20°C is 0.789 g/ml. 1 15.2 0.253 60.1 100.0 0.789 78.9 0.253 3.21 3.21 0.0789 mole moles urea g mole g g mass ethanol ml g ml mole mole molality m Kg Kg =× = === 6. What are the molarities of the solutes listed below when dissolved in water? a) 25 1.50 mole C H OH in 4.80 1 of solution 1.50 0.312 4.80 0.312 AA moles solute mole mole molarity or liter ratio M == = b) 3 12.5 g CH OH in 50.0 ml of solution 3 1 12.5 0.312 32.1 0.312 0.391 7.82 7.82 0.0500 mole mole moles CH OH g or gl M mole mole molarity or M ll c) ( ) 383 10.0 ml pure glycerol C H O , with density = 1.26 g/ml, in 250.0 ml solution. 10.0 1.26 12.6 1 12.6 0.137 92.1 0.137 0.548 0.548 0.250 g mass glycerol ml g ml mole moles glycerol g mole g mole mole molarity or M
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Nielsen Bhaskar/PC/1713Q/K 3/05 4 d) () 2 2 125 g CO NH , 98.6% pure, in 500.0 ml solution. 2 2 2 2 125 0.986 123 1 125 2.08 60.1 0.137 4.16 4.16 0.5000 AA mass pure CO NH g g mole molarity CO NH g mole g mole mole molarity or M =×= = == 7. Calculate the weight of each of the following needed to prepare 2000 ml of a 1.50 M solution: in liters M× V =m o l e s s o l u t e 1.50 2.000 3.00 A A moles moles solute required ×= (a) 44 3 3 , 3.00 149 447 g NH PO moles g NH PO mole (b) 23 , 3.00 106 318 g Na CO moles g Na CO mole
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This note was uploaded on 12/12/2011 for the course CHM 2041 taught by Professor Staff during the Fall '09 term at Santa Fe College.

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Ans_Ex3 - Nielsen CHM1041 Answer Key Set 3 1. What is the...

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