Asked Feb 10, 2020

An aqueous solution of Na2SOis prepared and its measured freezing point is -16.0o C. Calculate the molarity of the solution. The density of the solution is 1.10g/mL. Kfor water is 1.86o C/m. 


Expert Answer

Step 1

The depression or lowering in freezing point is expressed as:

Chemistry homework question answer, step 1, image 1


The molality  and molarity are related as follows :

Chemistry homework question answer, step 1, image 2


Step 2


Freezing point of solution, Tf = -16.0 oC

Freezing point of solvent (water), Tfo = 0 oC

Freezing point depression constant, Kf = 1.86 oC/m

Density of the solution = 1.10g/mL


Na2SO4 (aq) →2  Na+ (aq) + SO42- (aq)

Here, i = number of ions dissociated = 2 + 1 = 3



△Tf = Freezing point of solvent – Freezing point of solution

△Tf = 0 oC – (–16.0 oC)

△Tf = 16.0 oC


Substituting the values of △Tf , i and Kf in equation (1), we get,

Chemistry homework question answer, step 2, image 1

Step 3

Now, given density, d =  1.10g/mL

Molar mass of Na2SO4 , MB = (2×23) + 32 + (4×16) = 142 g/mol


The molarity can be calculated using equation (2) as follows :

Chemistry homework question answer, step 3, image 1


Want to see the full answer?

See Solution

Check out a sample Q&A here.

Want to see this answer and more?

Solutions are written by subject experts who are available 24/7. Questions are typically answered within 1 hour.*

See Solution
*Response times may vary by subject and question.
Tagged in



Related Chemistry Q&A

Find answers to questions asked by student like you
Show more Q&A

Q: Urea (NH2CONH2) is the end product in protein metabolism in animals. The decomposition of urea in 0....

A: Given: NH2CONH2(aq) + H+(aq) + 2H2O(l) → 2NH4+(aq) + HCO3- (aq) It is first order reaction.    


Q: Carbon disulfide, CS2, is a volatile, flammable liquid. It has a vapor pressure of 400.0 mmHg at 28....

A: Vapor pressure (P1) = 760 mmHg (normal boiling point pressure) Normal boiling temperature (T1) = 46....


Q: An ideal RF value for a compound on a developed TLC plate is 0.30. How could you adjust the TLC deve...

A: Click to see the answer


Q: Americium-241 is used in smoke detectors. It has a first order rate constant for radioactive decay o...

A: Half-life of americium-241 is 59.4 days. Therefore, time = 3×59.4 days = 178.2 days.


Q: Determine the solubility

A: Henry’s law states that dissolved gases in liquid are directly proportional to the partial pressure ...


Q: What is the molar mass?

A: Given, Mass of carbohydrate  = 6.85g. Mass of water = 100.0g. Density = 1.024g/mL. Osmotic pressure ...


Q: Determine the freezing point of a solution that contains 83.8 g of naphthalene (C10H8, molar mass = ...

A: Molality of solution can be calculated as follows:


Q: Review I Constants I Periodic Table Microwave ovens use microwave radiation to heat food. The microw...

A: Specific heat capacity is 4.184 J/g.K. Heat applied = ? Initial temperature = 25oC = 298 K Final tem...


Q: Hydrofluoric acid, an aqueous solution containing dissolved hydrogen fluoride, is used to etch glass...

A: Given, the unbalanced chemical equation - The weight of silica = 5.68 g Now we will balanced the ch...