How many grams of ethylene glycol, C2H4(OH)2, must be added to 400.0 g of water

Question

How many grams of ethylene glycol, C2H4(OH)2, must be added to 400.0 g of water to yield a solution that will freeze at -8.35 °C?
a) 75
b) 111 g
c) 37
d) 151

Question 2
What is the molarity of 87% phosphoric acid solution? (Density of the solution is 1.46 g/mL)
a) 39.0 M
b) 87.0 M
c) 13.0 M
d) 1.46 M

Question 3
Concentrated hydrochloric solution has molarity of 12.3 M. If the density of the solution is 1.19 g/mL, what is the % by mass for hydrochloric acid?
a)11.9%
b)75.4%
c) 37.7%
d) 12.3%

Question 4
I have a bottle of NH3. Its strength is 32.0% and its density is 0.89 g/mL. How do I figure out the molarity?
a) 5.0 M
b)16.7 M
c) 23.0 M
d) 8.9 M

Question 5
Generally, for solubility of a gas, as the temperature_________ the solubility _________.
a) decreases, does not change
b) increases, increases
c) increases, decreases
d) decreases, decreases

Question 6
A common laboratory technique for degassing a solvent is to place it in a flask that is sealed to the atmosphere and then evacuate the flask to remove any gases above the liquid. Why is this procedure effective?
a) Increasing the pressure of a gas above the liquid decreases it's solubility
b) solubility of gas is independent of it's pressure
c) decreasing the pressure of a gas above the liquid decreases it's solubility
d )decreasing the pressure of a gas above the liquid increases it's solubility

Question 7
Which of the solution has the highest freezing point?
a) 0.25 m CH3OH
b) 0.05 m K2SO4
c) 0.1 m NaCl
d) 0.1 m MgBr2

Question 8

What is the molar solubility (in M) of helium at 1.0 atm and 25 oC?

a) 0.037
b) 0.00037
c) 0.37
d) 0.0037

Question 9
Which compound has the highest solubility in water?
a) O2                 
b) NH3
c) CH4                
d) CO2

Explanation / Answer

1.

DTf = i*kf*m

(0+8.35) = 1*1.86*(w/62.07)*(1000/400)

w = 111.45 grams

2. 87% solution.

mass of phosphoric acid solution = 87 grams

mass of solution = 100 grams

Volume of solution = 100/1.46 = 68.5 ml

molarity = (87/98)*(1000/68.5)

     = 12.96

answer: C) 13.0 M

3.

M = %w*1000*density /mwt

12.3 = x*1000*1.19 / 36.5

x = 0.377

% = 37.7

answer: 37.7%

4.

M = 0.32*1000*0.89 / 17

   = 16.7 M

answer: 16.7 M

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