Which particles are equal in number for an atom with a neutral charge?

A 0.2436-g sample of an unknown substance was dissolved in 20.0 ml of cyclohexane. The density of cyclohexane is 0.779 g/ml. The

Viktor [21]

The depression in freezing point is related to molality of solution as follows:

$\Delta T_{f}=k_{f}m$

Here, $k_{f}$ is freezing point depression constant, for cyclohexane it is equal to 20°C kg/mol.

The value of freezing-point depression is 2.5 °C, molality can be calculated as follows:

$m=\frac{\Delta T_{f}}{k_{f}}=\frac{2.5 ^{o}C}{20 ^{o}C kg/mol}=0.125 mol/kg$

Molality is defined as number of moles of solute in 1 kg of solvent.

Here, solvent is cyclohexane, its volume is given 20.0 mL and density is 0.779 g/mol thus, mass of cyclohexane can be calculated as follows:

$m=d\times V=0.779 g/mL\times 20 mL=15.58 g$

Converting this into kg,

$1 g=10^{-3} kg$

Thus, 15.58 g will be 0.01558 kg.

Now, number of moles of unknown solute is related to its mass and molar mass as follows:

$n=\frac{m}{M}$

Putting the values of mass of solute which is 0.2436 or 0.0002436 kg

$n=\frac{ 0.0002436 kg}{M}$

Now, expression for molality of solution is:

$m=\frac{n_{solute}}{m_{solvent}}$

Putting all the values,

$0.125 mol/kg=\frac{0.0002436 kg}{M\times 0.01558 kg}$

Or,

$0.125 mol/kg=\frac{0.015635}{M}$

On rearranging,

$M=\frac{0.015635}{0.125 mol/kg}=0.1250 kg/mol$

Or,

$M=0.125 kg/mol(\frac{1000 g}{1 kg})=125 g/mol$

Therefore, molar mass of unknown sample is 125 g/mol

5 0

4 years ago

Which is a resource that the National Park Service manages?

pantera1 [17]

Answer:

to preserve the integrity of the wildlife refuge, ecosystems and the endangered species.

Explanation:

A national park service manages

4 0

3 years ago

Four properties of water are listed. It has high thermal conductivity. It reacts with metals to form metal hydroxide and hydroge

erica [24]

Answer:

The chemical properties are then number 2 and 4:

It reacts with metals to form metal hydroxide and hydrogen gas.

It decomposes to form hydrogen and oxygen.

Justification:

The chemical properties can only be observed when the substance undergoes a chemical change, which is that the substance is transformed into one or more different substances. As result of a chemical change, the composition of the former substance changes, braking some chemcial bonds and formng new ones.

The number 1 states that the water reacts with metals to form metal hydroxide, meaning that the water is transformed into a new substance, the composition will not be H₂O andy more, since the atoms will be combined with atoms of different elements. Same, can be told about the number 2, which states that hydrogen and oxygen were obtained when water decomposed.

On the other hand, the thermal conductivity of water and the boiling point (the temperature at which the water evaporates) can be measured without changing the composition of the water, so those are physical properties.

5 0

3 years ago

Read 2 more answers

PLEASE HELP!! ILL MARK BRAINLIST!!

Lynna [10]

Ok I will get a hold on you tomorrow morning to see

8 0

3 years ago

What change would not result in a shift of the equilibrium position to the left?

padilas [110]

Option 1) increasing the pressure will not result in a shift of the equilibrium position to the left. Le Chatelier's Principle states that when the pressure is increased the equilibrium will shift to the direction where fewer moles of gas is produced. Since there are equal moles of gas on the left and right side of the equation, the increased pressure will not affect the equilibrium.

Further Explanation:

Option 2) adding more of gas C to the system SHIFTS THE EQUILIBRIUM POSITION TO THE LEFT because increasing the amount of gas on the right side can be relieved by using up the added C to form A and B.

Option 3) removing some of A from the system SHIFTS THE EQUILIBRIUM POSITION TO THE LEFT because the system will restore the lost reactant by using up C to form more of A.

Option 4) cooling the system SHIFTS THE EQUILIBRIUM POSITION TO THE LEFT because the forward reaction is exothermic. Therefore, removing heat from the system will drive the backward reaction to occur.

Learn More

Learn more about Le Chatelier's Principle brainly.com/question/4356622
Learn more about Equilibrium brainly.com/question/538664
Learn more about Equilibrium Constant brainly.com/question/4137132

Keywords: pressure, equilibrium, Le Chatelier's Principle

4 0

4 years ago

Which particles are equal in number for an atom with a neutral charge? ​

Which particles are equal in number for an atom with a neutral charge?