Question

1.)Equal masses of water and ethylene glycol (C2H6O2) are mixed. At what temperature will the mixture freeze? The molal freezing point constant for water is 1.86 ºC/m.

2.)The vapor pressure of a liquid depends on?

3.)How many atoms are in a body centered cubic lattice?

Answer 1

1) The molal freezing point of water = 1.86

Let mass of each is y grams

so depression in freezing point = Kf X molality of water

molality = mass of glycol   / molar mass of glycol X mass of water

molality = y / 62 X y

molality = 1 / 62 = 0.0161 molal

So freezing point depression = 1.86 X 0.0161 = 0.03⁰C

So the water will freeze at -0.03⁰C

2) the vapour pressure of liquids depends only upon the temperature.

3) There are eight atoms at each corner of the cube in body centered cubic lattice and one atom at the centre of body.

Each atom at corner will contribute 1/8th to the cube so total contribution of atoms at corners = 1/8 X 8 =1

Atom in centre will contribute to the cube = 1

so total atoms in BCC = 2