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3 years ago

Which of the following is a physical property of a substance?

1 answer:

8 0

B boiling point https://chem.libretexts.org/Bookshelves/Introductory_Chemistry/Map%3A_Introductory_Chemistry_(Tro)/03%3A_Matter_and_Energy/3.05%3A_Differences_in_Matter%3A_Physical_and_Chemical_Properties#Summary

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"An aqueous CaCl2 solution has a vapor pressure of 83.1mmHg at 50 ∘C. The vapor pressure of pure water at this temperature is 92

Lynna [10]

Answer : The the concentration of $CaCl_2$ in mass percent is, 41.18 %

Solution : Given,

Molar mass of water = 18 g/mole

Molar mass of $CaCl_2$ = 110.98 g/mole

First we have to calculate the mole fraction of solute.

According to the relative lowering of vapor pressure, the vapor pressure of a component at a given temperature is equal to the mole fraction of that component of the solution multiplied by the vapor pressure of that component in the pure state.

$\fac{p^o-p_s}{p^o}=X_B$

where,

$p^o$ = vapor pressure of the pure component (water) = 92.6 mmHg

$p_s$ = vapor pressure of the solution = 83.1 mmHg

$X_B$ = mole fraction of solute, $(CaCl_2)$

Now put all the given values in this formula, we get the mole fraction of solute.

$\fac{92.6-83.1}{92.6}=X_B$

$X_B=0.102$

Now we have to calculate the mole fraction of solvent (water).

As we know that,

$X_A+X_B=1\\\\X_A=1-X_B\\\\X_A=1-0.102\\\\X_A=0.898$

The number of moles of solute and solvent will be, 0.102 and 0.898 moles respectively.

Now we have to calculate the mass of solute, $(CaCl_2)$ and solvent, $(H_2O)$ .

$\text{Mass of }CaCl_2=\text{Moles of }CaCl_2\times \text{Molar mass of }CaCl_2$

$\text{Mass of }CaCl_2=(0.102mole)\times (110.98g/mole)=11.32g$

$\text{Mass of }H_2O=\text{Moles of }H_2O\times \text{Molar mass of }H_2O$

$\text{Mass of }H_2O=(0.898mole)\times (18g/mole)=16.164g$

Mass of solution = Mass of solute + Mass of solvent

Mass of solution = 11.32 + 16.164 = 27.484 g

Now we have to calculate the mass percent of $CaCl_2$

$Mass\%=\frac{\text{Mass of}CaCl_2}{\text{Mass of solution}}\times 100=\frac{11.32g}{27.484g}\times 100=41.18\%$

Therefore, the the concentration of $CaCl_2$ in mass percent is, 41.18 %

4 0

2 years ago

To prepare an acetic acid/acetate buffer, a technician mixes 30.6 mL of 0.0880 acetic acid and 21.6 mL of 0.110 sodium acetate i

enyata [817]

Answer: There are 0.00269 moles of acetic acid in buffer.

Explanation:

To calculate the number of moles for given molarity, we use the equation:

$\text{Molarity of the solution}=\frac{\text{Moles of solute}\times 1000}{\text{Volume of solution in ml}}$ .....(1)

Molarity of acetic acid solution = 0.0880 M

Volume of solution = 30.6 mL

Putting values in equation 1, we get:

$0.0880M=\frac{\text{Moles of acetic acid}\times 1000}{30.6ml}\\\\\text{Moles of acetic acid}=\frac{0.0880\times 30.6}{1000}=0.00269mol$

Thus there are 0.00269 moles of acetic acid in buffer.

8 0

2 years ago

How does the burning of fossil fuels increase the greenhouse effect answers?

miskamm [114]

The burning of fossil fuels like coal, natural gas etc... leads to the emmission of carbondioxide which is a green house gas and leads to the increase of heat in the atmosphere. This results in greenhouse effect.

8 0

3 years ago

3. Write a hypothesis that explains your inference about the acidity of the paper. How might you test your hypothesis by extendi

vredina [299]

Answer:

google

Explanation:

go to the plus thing on your screen and search it. (please dont attack me im doing a dare >:( )

8 0

3 years ago

Which animal can leave its eggs to hatch and does not need to take care of the infants?

Murljashka [212]

Sea turtles they leave them on the beach

4 0

2 years ago

Read 2 more answers