of lead? 6) A solution is 30% KOH by mass in water and has density of 1.29 g/ml.

Question

of lead? 6) A solution is 30% KOH by mass in water and has density of 1.29 g/ml. Determine: a the molarity ) the molality the mole fraction of KOH What is the Henry's law constant (in M/atm) for the dissolution of helium in water if the concentration of helium in water is 1.47 x 10 M at a partial pressure of 293 mm Hg? Benzene. CoH, (k,--5. 120 C/m), normally freezes at 55°C. The addition of 1 gram of X to 8.5 grams of CSH, lowers the freezing point to 3.37 What is the molar mass of X? 9) How many grams of CioH, must be added to 25 grams of CCl, to produce a solution with a vapor pressure of 483 mm Hg? Pure CCl, has a vapor pressure of 504 mm Hg at this temperature 10) A 0.10 gram sample of a hormone dissolved in 125 mL of solution produces an osmotic pressureo

Explanation / Answer

Q6

if 30% is KOH, then

a)

Molarity = mol of KOH / Volume of solution

assume 100 g of mix

30 g of KOIH, 70 g of water

mol of KOH = mass/MW = 30/56.10564 = 0.5347

Volume = mass/D = 100/1.29 = 77.5 mL = 77.5*10^-3 L

[KOH] = mol/V = 0.5347/( 77.5*10^-3) = 6.8993 M

b)

molality = mol of KOH / kg water = 0.5347 / (70*10^-3) = 7.64 molal

c)

mol frac.

mol of H2O = mass/MW = 70/18 = 3.888

total mol = 3.888+0.5347 = 4.4227

x-KOH = mol of KOH / total mol = 0.5347 /4.4227 = 0.1208

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