Discussion2 soln

Discussion2 soln - 2(given(need mol NaCl = 58.00 g 1 mol...

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Question 1 Discussion #2 Chem002 Spring 2008

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[2] George is making spaghetti for dinner, because he is a college student that cannot afford to take his date out to a real restaurant. Since he is Canadian, he places 4.010 kg of water in a pan and brings it to a boil. Before adding the pasta, he adds 58.00 g of table salt to the water and again brings it to a boil. It is a nice day at sea level so that pressure is 1.000 atm. Assume negligible evaporation of water. Kb for water is 0.5200 °C/ m . What is the temperature of the salty, boiling water in °C? Why does George salt the water ? Δ T B = i K B m Bp (soln) - normal Bp (T B ) = Δ T B i =2 (Na + + Cl - ) = mol NaCl/ kg H
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Unformatted text preview: 2 (given) (need) mol NaCl = 58.00 g 1 mol NaCl 58.44 g NaCl) x = 0.9925 mol NaCl m = mol NaCl/kg solvent = 0.9925 mol NaCl/ 4.010 kg H 2 O = 0.2475 m Δ T B = i K B m = 2(0.5200 o C/ m )(0.2475 m ) = 0.2574 o C [3] The Henry's law constant for helium gas in water at 30 °C is 3.70 × 10-4 M/atm. When the partial pressure of helium above a sample of water is 0.650 atm, what is the concentration of helium in the water in M ? (a) Bp (soln) = normal Fp (T B ) + Δ T B = 100 o C * 0.2574 o C = 100.3 o C (b) Because George must like salty water. S g = kP g = (3.70x10-4 M /atm)(0.650 atm) = 2.41 x 10-4 M...
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Discussion2 soln - 2(given(need mol NaCl = 58.00 g 1 mol...

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