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3 years ago

Which statement is true about the elements present in a pure substance?

Chemistry

2 answers:

djverab [1.8K]3 years ago

8 0

I'm not sure but I think is C or D.

Makovka662 [10]3 years ago

4 0

Answer: Option (D) is the correct answer.

Explanation:

An element is defined as a substance that contains atoms of one type.

For example, a piece of sodium metal will contain only atoms of sodium.

Therefore, it is a pure substance. Whereas a compound is a substance that consists of two or more different atoms in similar composition.

For example, $CaCl_{2}$ is a compound.

When elements change into compounds then they tend to change their chemical properties.

Hence, we can conclude that the statement they can only be separated by chemical methods, is true about the elements present in a pure substance.

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At 298 K, the osmotic pressure of a glucose solution (C6H12O6 (aq)) is 12.1 atm. Calculate the freezing point of the solution. T

Anarel [89]

Answer: The freezing point of solution is -0.974°C

Explanation:

To calculate the concentration of solute, we use the equation for osmotic pressure, which is:

$\pi=iMRT$

where,

$\pi$ = osmotic pressure of the solution = 12.1 atm

i = Van't hoff factor = 1 (for non-electrolytes)

M = molarity of solute = ?

R = Gas constant = $0.0821\text{ L atm }mol^{-1}K^{-1}$

T = temperature of the solution = 298 K

Putting values in above equation, we get:

$12.1atm=1\times M\times 0.0821\text{ L.atm }mol^{-1}K^{-1}\times 298K\\\\M=\frac{12.1}{1\times 0.0821\times 298}=0.495M$

This means that 0.495 moles of glucose is present in 1 L or 1000 mL of solution

To calculate the mass of solution, we use the equation:

$\text{Density of substance}=\frac{\text{Mass of substance}}{\text{Volume of substance}}$

Density of solution = 1.034 g/mL

Volume of solution = 1000 mL

Putting values in above equation, we get:

$1.034g/mL=\frac{\text{Mass of solution}}{1000mL}\\\\\text{Mass of solution}=(1.034g/mL\times 1000mL)=1034g$

To calculate the number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$

Moles of glucose = 0.495 moles

Molar mass of glucose = 180.16 g/mol

Putting values in above equation, we get:

$0.495mol=\frac{\text{Mass of glucose}}{180.16g/mol}\\\\\text{Mass of glucose}=(0.495mol\times 180.16g/mol)=89.18g$

Depression in freezing point is defined as the difference in the freezing point of pure solution and freezing point of solution.

The equation used to calculate depression in freezing point follows:

$\Delta T_f=\text{Freezing point of pure solution}-\text{Freezing point of solution}$

To calculate the depression in freezing point, we use the equation:

$\Delta T_f=iK_fm$

Or,

$\text{Freezing point of pure solution}-\text{Freezing point of solution}=i\times K_f\times \frac{m_{solute}\times 1000}{M_{solute}\times W_{solvent}\text{ (in grams)}}$

where,

Freezing point of pure solution = 0°C

i = Vant hoff factor = 1 (For non-electrolytes)

$K_f$ = molal freezing point elevation constant = 1.86°C/m

$m_{solute}$ = Given mass of solute (glucose) = 89.18 g

$M_{solute}$ = Molar mass of solute (glucose) = 180.16 g/mol

$W_{solvent}$ = Mass of solvent (water) = [1034 - 89.18] g = 944.82 g

Putting values in above equation, we get:

$0-\text{Freezing point of solution}=1\times 1.86^oC/m\times \frac{89.18\times 1000}{180.16g/mol\times 944.82}\\\\\text{Freezing point of solution}=-0.974^oC$

Hence, the freezing point of solution is -0.974°C

8 0

3 years ago

Four processes that change rock from one type to another.

Cloud [144]

Erosion
waethring
deposition
pressure or heat
all of this can change the form of rock to another

8 0

2 years ago

4. Can 200 ml of fluid be transferred to a 1-quart container? Explain the process that you used to arrive at your answer.

sukhopar [10]

Answer:

Yes, 200 ml of fluid can be transferred to a 1-quart container.

Explanation:

You must compare the two volumes, 200 ml and 1 quart. If 200 ml is less than or equal to 1 quart, then 200 ml of fluid can be transferred to a 1-quart container, else it is not possible.

To compare, the two volumes must be on the same system of units.

Quarts is a measure of volume equivalent to 1/4 of gallon.

One gallon is approximately 3.785 liters.

3.785 liter = 3.785 liter × 1,000 ml/liter

Then, to convert 1 quart to ml use the unit cancellation method:

(1/4)gallon × 3.785 liter/gallon × 1,000ml / liter = 946.25 ml

Thus, you get that a 1-quart container has volume of 946.25 ml, which allows that 200ml of fluid be transferred to it.

7 0

3 years ago

Conner is testing the pH of a swimming pool and he finds it to be 6.5. Optimal pH for swimming is between 7.0 and 7.6.

Lunna [17]

Answer:

The answer is B. I took the test and made a 100

Explanation:

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2 years ago

Is methane used as fule gas true or false

Hitman42 [59]

Answer:

its true methane is used as a fuel gas

Explanation:

4 0

2 years ago