Chemistry, 07.12.2019 00:31, mzrereday3151

If we have three different solutions, a, b, and c, each containing 100 g of water, plus respectively 6.84 g of sucrose (c12h22o11), 0.72 g of ethanol, and 0.40 g of sodium hydroxide, which statement is true?

a. c has the lowest freezing point in the group.
b. a, b, and c all have different freezing points.
c. a and c have the same boiling point, but b has a lower one.
d. the boiling point of c is lower than that of a or b e. a, b, and c will all have about the same freezing points

Answers: 3

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answered: kaoris2322

c. A and C have the same boiling point, but B has a lower one.

Explanation:

The freezing point depression is expressed as:

ΔT = kf×m

Where kf is the freezing point depression constant that depends the nature of the solvent and m is molality (mol of solute/kg of solvent)

Boiling point elevation is:

ΔT = kb×m

Where kb is the ebulloscopic constant of the solvent.

As kf, kb and mass of solvent is the same for A, B and C solutions the only difference will be in moles of solute.

A 6,84g of sucrose are:

6,84g× $\frac{1mol}{342,3g}$ = 0,002 moles

B 0,72g of ethanol are:

0,72g× $\frac{1mol}{46,1g}$ = 0,0016 moles

C 0,40g of sodium hydroxide are:

0,40g× $\frac{1mol}{40g}$ = 0,001 moles

Using Van't Hoff factor that describes the number of moles in solution that comes from 1 mole of solute before dissolving, moles in solution for A, B and C are:

A. moles in solution: 0,02 moles×1 = 0,02 moles in solution

B. moles in solution: 0,016 moles×1 = 0,016 moles in solution

C. moles in solution: 0,01 moles×2 = 0,02 moles in solution

As A has the same moles in solution of C, the freezing point depression will be the same in A and C, and the lower freezing point depression will be in B.

Also, the boiling point will be higher in A and C, and then in B.

Thus:

a. C has the lowest freezing point in the group. FALSE. A and C have the lowest feezing point because have the higher freezing point depression.

b. A, B, and C all have different freezing points. FALSE. As moles of A and C are the same, freezing point will be the same for the solutions.

c. A and C have the same boiling point, but B has a lower one. TRUE.

d. The boiling point of C is lower than that of A or B . FALSE. Boiling point of C and A is higher than B.

e. A, B, and C will all have about the same freezing points. FALSE

answered: Guest

The gas would begin to expand, and eventually the can would burst or explode.

answered: Guest

because u need two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei to form isotopes.

so since they all have the same shape? i mean maybe because m& m and reeses are both chocolates

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If we have three different solutions, a, b, and c, each containing 100 g of water, plus respectively...