Chemistry, 05.07.2020 14:01 queenjanet46

Suppose that you add 26.7 g of an unknown molecular compound to 0.250 kg of benzene, which has a K f of 5.12 oC/m. With the added solute, you find that there is a freezing point depression of 2.74 oC compared to pure benzene. What is the molar mass of the unknown compound

Answers: 1

Show answers

Answers

Answer from: NotYourStudent

The molar mass of an unknown solute compound in the solution has been 199.626 g/mol.

With the addition of the solute to the solution, there has been a depression in the freezing point. The depression in the freezing point can be expressed as:

Depression in freezing point = Van't Hoff factor × Freezing point constant × molality

The molality can be defined as the moles of solute per kg solvent

Molaity = $\rm \dfrac{Mass\;of\;solute\;(g)}{Molecular\;mass\;of\;solute}\;\times\;\dfrac{1}{Mass\;of\;solvent\;(kg)}$

The depression in freezing point can be given as:

Depression in freezing point = Van't Hoff factor × Freezing point constant × $\rm \dfrac{Mass\;of\;solute\;(g)}{Molecular\;mass\;of\;solute}\;\times\;\dfrac{1}{Mass\;of\;solvent\;(kg)}$ ......(i)

Given, the depression in freezing point = 2.74 $\rm ^\circ C$

Van't Hoff factor = 1 (Molecular compound)

Freezing point constant (Kf) = 5.12 $\rm ^\circ C$ /m

Mass of solute = 26.7 g

Mass of solvent = 0.250 kg

Substituting the values in equation (i):

2.74 $\rm ^\circ C$ = 1 × 5.12

$\rm \dfrac{2.74}{5.12}$ = $\rm \dfrac{1}{Molecular\;mass\;of\;solute}\;\times\;\dfrac{26.7}{0.250\;kg}$

0.535 = $\rm \dfrac{1}{Molecular\;mass\;of\;solute}\;\times\;106.8$

Molecular mass of solute = $\rm \dfrac{106.8}{0.535}$ g/mol

Molecular mass of solute = 199.626 g/mol

The molar mass of an unknown solute compound in the solution has been 199.626 g/mol.

For more information about the molality of the compound, refer to the link:

link

Answer from: imsmart916

The molar mass of the unknown compound is 200 g/mol

Explanation:

Depression in freezing point is given by:

$\Delta T_f=i\times K_f\times m$

$\Delta T_f=2.74^0C$ = Depression in freezing point

i= vant hoff factor = 1 (for molecular compound)

K_f = freezing point constant = 5.12^0C/m

m= molality

$\Delta T_f=i\times K_f\times \frac{\text{mass of solute}}{\text{molar mass of solute}\times \text{weight of solvent in kg}}$

Weight of solvent (benzene)= 0.250 kg

Molar mass of solute = M g/mol

Mass of solute = 26.7 g

$2.74^0C=1\times 5.12\times \frac{26.7g}{Mg/mol\times 0.250kg}$

M=200g/mol

Thus the molar mass of the unknown compound is 200 g/mol

Answer from: Quest

people flirt to show their affection towards someone in a less forward way then telling. they want the other person to guess what they’re feeling to have the other person also start to like them

Answer from: Quest

1. and 2. question: in which equation? or i don't understand you, 3. a), 4. c), 5. c), 6. b), 7. d), 8. d) if small number is underlined(behind symbol) , b) if big number is underlined(in front of symbol)9. what is underlined there? 10. c)

Another question on Chemistry

Chemistry, 22.06.2019 00:30

The clouds are grey and ground is wet. a quantitative b qualitative

Answers: 1

Answer

Chemistry, 22.06.2019 03:20

What is the ima of the 1 st class lever in the graphic given? 2 3 0.5

Answers: 1

Answer

Chemistry, 22.06.2019 10:30

Skills of homo sapiens were found an excavation. the skulls were preserved because the bodies were frozen. so, these fossils are (blank) fossils.the image shows the evolution of skulls beginning 2 to 3 million years ago. based on the image, modern human skulls(blank) ape skulls.

Answers: 1

Answer

Chemistry, 23.06.2019 04:10

Which of the following is described by the equation h2o(s)+ heat=h2o(i) a freezing melting condensing evaporating

Answers: 2

Answer

You know the right answer?

Suppose that you add 26.7 g of an unknown molecular compound to 0.250 kg of benzene, which has a K f...

Questions