Calculate the vapor pressure (in torr) at 298 K in a solution prepared by dissolving 38.5 g of the non-volatile non-electrolye urea {CO(NH2)2} in 142 g of methanol. The vapor pressure of methanol at 298 K is 122.7 torr. Give your answer to 2 decimal places.

The vapor pressure of methanol solution at 298K is 107.12 torr

Explanation:

As the relative lowering of vapor pressure is directly proportional to the amount of dissolved solute.

The formula for relative lowering of vapor pressure will be,

where,

= relative lowering in vapor pressure

i = Van'T Hoff factor = 1 (for non electrolytes)

= mole fraction of solute  =

Given : 38.5 g of urea is present in 142 g of methanol

moles of solute (urea) =

moles of solvent (methanol) =

Total moles = moles of solute  + moles of solvent  = 0.64 + 4.4 = 5.04

= mole fraction of solute  =

Thus the vapor pressure of methanol solution at 298K is 107.12 torr

you need to take a look at the periodic system in order to sort these elements into pairs that would most likely exhibit similar chemical properties. first, you need to find elements that are found in the same group (groups are vertical in the periodic system), and then to see whether they have the same valence number. if they meet these criteria, they will have similar properties.

the first pair: ne (neon) and kr (krypton), are noble gases found in group 8

the second pair: li (lithium) and k (potassium), found in group 1

the third pair: s (sulfur) and te (tellurium), found in group 6

i believe it is-

d.) gravity pulled particles of dust and gas together to form planets.