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3 years ago

A number should be rounded up if

Chemistry

1 answer:

Vedmedyk [2.9K]3 years ago

6 0

Answer:

C.) The number after it is between 5 and 9

Explanation:

If the digit to the right is less than five, you must leave the digit you want to round to as it is.

But, if the digit to the right is greater than or equal to five, you must increase the value of the digit you're rounding to by one. And any remaining digits before the decimal point become zeros, and any that are after the decimal point are dropped.

Hope this helps you out! : )

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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

3 years ago

How much heat is lost or gained by the calorimeter

Maslowich

Answer:

1.113 kJ or 1,113 J.

Explanation:

I hope this helps :)

5 0

3 years ago

The standard cell potential (E°cell) for the reaction below is +0.63 V. The cell potential for this reaction is ________ V when

Natasha_Volkova [10]

Answer: 0.52V

Explanation:

Ecell = Ecell(standard) - [(0.0592 logQ)/n]

Q = product of the quotient

n = no of electrons transferred = 2

Ecell = 0.63 - [(0.0592*Log(1 / 2.0 * 10-4) / 2]

Ecell = 0.63 - 0.0194

Ecell = 0.5205V

5 0

3 years ago

Please help! If a forensic chemist discovers evidence through examination which would prove a person guilty of a crime, why then

Bogdan [553]

Explanation: You cannot be convicted of a crime without evidence. You cannot be convicted of a state crime. You cannot be convicted of a federal crime. If there is no evidence against you, under the law, it simply is not possible for the prosecutor's office to obtain a conviction at trial. So, when you do have evidence it is really impossible to not get convicted unless the judge truly believes your side of the story and declares you not guilty.

I hope this helped :) If not i'm sorry!

7 0

3 years ago

What two gases have a profound effect on the type of organisms that can live in an area and influences the regions carrying capa

Over [174]

Answer:

Oxygen and Carbon dioxide

Explanation:

Oxygen is required for respiration whereby energy is released from natural occurring nutrients accompanied by the release of water and carbon dioxide. carbon dioxideis also required by plants to photosynthesise.

Oxygen and carbon dioxide in the troposphere supports life as by enabling respiration in organisms and photosynthesise in plants can. Without oxygen in an environment, only life forms that live by anaerobic respiration will thrive. This affects a regions carrying capacity

3 0

3 years ago