Calculate the Molar Mass (g/mol) of an unknown nonelectrolyte if the osmotic pressure exerted by dissolving 44.2 mg of it in 358 mL of solution at 25.0 oC is 12.7 torr. a) 104 b) 181 c) 203 d) 78.6 e) 167 f) 283 g

b) 181

Explanation:

T = 25 + 273 = 298K (Upon converting to Kelvin Temperature)

Osmotic pressure, π = 12.7 torr = 0.0167 atm ( converting to atm by dividing the pressure value by 760 )

The equation relating these variables is given as;

π = MRT

M = π / RT

R = gas constant = 0.0821 L atm/mol K

Upon solving for M;

M = 0.0167 / ( 0.0821 * 298)

M = 0.0167 / 24.47

M = 0.000682 M

The mass concentration = Mass / Volume

Mass conc = 44.2 mg / 358

Mass conc = 0.1235g/l

The relationship between the molar concentration and mass concentration is;

Molar mass = Mass conc / Molar conc

Upon substituting the values we have;

Molar mass = 0.1235 /  0.000682

Molar mass = 181.09 g/mol

The correct option is option B.

- decrease the number of plants and animals living in the water.

the ideal gas law equation is as follows

pv = nrt

where p - pressure

v - volume

n - number of moles

r - universal gas constant

t - temperature

so if the pressure, volume and temperature are already known

we are left with n and r

since r is the universal gas constant that has a known fixed value then r too is known

so we are left with 'n'

once we know temperature volume and pressure

we can find the number of moles of gas present using the ideal gas law equation

this is not my own answer, this is an answer for the same question by the user blahblahmali. i do not claim ownership of this account.