All categories

3 years ago

What molality of nonvolatile solute is needed to lower the melting point of camphor by 1.010°c? (kf = 39.70ºc/m)?

1 answer:

5 0

Molality is defined as the ratio of moles of solute to the mass of solvent in Kg. It is also known as molal concentration.

Formula used for determining the molality is:

$\Delta T=K_{f}\times m$ (1)

where,

$\Delta T$ = change in temperature

$K_{f}$ = freezing point depression constant

m = molality

Here, $\Delta T$ = $1.010^{0}C$ and $K_{f}$ = $39.70^{0}C/m$

Put the above values in formula (1)

$1.010^{0}C=39.70^{0}C/m\times m$

$m=\frac{1.010^{0}C}{39.70^{0}C}$

= $0.0254 m$

Hence, molality of nonvolatile solute is $0.0254 m$

You might be interested in

A vessel contains a mixture of gases. The mass of each gas used to make the mixture is known. Which of the following information

faltersainse [42]

Answer: The molar mass of each gas

Explanation:

Mole fraction is the ratio of moles of that component to the total moles of solution. Moles of solute is the ratio of given mass to the molar mass.

$\text{Mole fraction of solute}=\frac{\text{Moles of solute}}{\text{Total Moles}}$

Suppose if there are three gases A, B and C.

a) $\text{Mole fraction of A}=\frac{\text{Moles of A}}{\text{ Moles of (A+B+C)}}$

b) $\text{Mole fraction of B}=\frac{\text{Moles of B}}{\text{ Moles of (A+B+C)}}$

c) $\text{Mole fraction of C}=\frac{\text{Moles of C}}{\text{ Moles of (A+B+C)}}$

moles of solute = $\frac{\text {given mass}}{\text {Molar mass}}$

Thus if mass of each gas is known , we must know the molar mass of each gas to know the moles of each gas.

8 0

3 years ago

A bottle of coke is 250.0 mL. What is the volume in cubic centimeters?

hoa [83]

Answer:

The volume in cubic centimeters is 250

Explanation:

The rule of three or is a way of solving problems of proportionality between three known values and an unknown value, establishing a relationship of proportionality between all of them.

If the relationship between the magnitudes is direct, that is, when one magnitude increases, so does the other (or when one magnitude decreases, so does the other), the direct rule of three must be applied. To solve a direct rule of three, the following formula must be followed:

a ⇒ b

c ⇒ x

So:

$x=\frac{c*b}{a}$

The direct rule of three is the rule applied in this case where there is a change of units. To perform this conversion of units, you must first know that 1 mL = 1 cubic centimeters. So, if 1 cubic centimeters is 1 mL, how many cubic centimeters equals 250 mL?

$cubic centimeters=\frac{250 mL*1 cubic centimeters }{1 mL}$

cubic centimeters= 250

The volume in cubic centimeters is 250

3 0

3 years ago

What is the theoretical yield of methanol (CH3OH) when 12.0 grams of H2 is mixed with 74.5 grams of CO? CO + 2H2 CH3OH

AlladinOne [14]

1) We need to convert 12.0 g of H2 into moles of H2, and 74.5 grams of CO into moles of CO
Molar mass of H2: M(H2) = 2*1.0= 2.0 g/mol
Molar mass of CO: M(CO) = 12.0 +16.0 = 28.0 g/mol

12.0 g H2 * 1 mol/2.0 g = 6.0 mol H2
74.5 g CO * 1 mol/28.0 g = 2.66 mol CO

2) Now we can use reaction to find out what substance will react completely, and what will be leftover.

CO + 2H2 -------> CH3OH
 1 mol 2 mol
given 2.66 mol 6 mol (excess)

How much
we need CO? 3 mol 6 mol

We see that H2 will be leftover, because for 6 moles H2 we need 3 moles CO, but we have only 2.66 mol CO.
So, CO will react completely, and we are going to use CO to find the mass of CH3OH.

3) CO + 2H2 -------> CH3OH
 1 mol 1 mol
 2.66 mol 2.66 mol

4) We have 2.66 mol CH3OH
Molar mass CH3OH : M(CH3OH) = 12.0 + 4*1.0 + 16.0 = 32.0 g/mol

2.66 mol CH3OH * 32.0 g CH3OH/ 1 mol CH3OH = 85.12 g CH3OH

Answer is D) 85.12 grams.

3 0

3 years ago

PLEASE HELP

Dovator [93]

Answer:

Explanation:

All elements on both sides of the equation have the same amount of moles

5 0

2 years ago

Name the organic compound of ch2=chch2ch3

Lena [83]

I don’t know what exactly is but see at the picture.