Question

1) Which of the following aqueous Cs₃PO₄ (MM = 494 g/mol) solutions each with a density of 1.1g/mL will have the higher molal concentration? Show work

a) 1M Cs₃PO₄

b) 1 m Cs₃PO₄

c) A and B are the same concentration

d) There is not enough information to give an answer?

2) Water and dimethyl ether are NOT miscible with one another because?

a) Both water and ether can be classified as polar molecules

b) water is polar and ether is nonpolar

c) Water has an oxygen with lone pairs

d) the shape of ether is bent

e) Ether has more carbons and hydrogens than water making it less polar to the point that the two liquids will not mix

Answer 1

Density = 1.1 g/ml Molecular Weight = 494

1) Molarity = No. of moles of solute / liters of solution

Molality = Moles of solute / Kg of solvent

To compare both of them I am converting 1M into 1m solution

Consider 1L solution, Total Mass of solution = 1000 mL x 1.1g/mL = 1100 g

1M solution means 1 mole of Cs₃PO₄ in 1 L solution = 494 g

No. of grams of solvent = Mass of solution - mass of solute = 1100 - 494 = 606 g

Molality = No. of moles of solute / Kg of solvent = 1/0.606 = 1.65

Therefore 1M Cs₃PO₄ has higher molal concentration than 1m Cs₃PO_4.

2) They are not miscible with one another since water is polar solvent and dimethyl ether is non polar