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3 years ago

11

What is the molality of a solution made by dissolving 137.9g of sucrose in 414.1g of water? The density of the solution is 1.104

g/ml.

1 answer:

prisoha [69]3 years ago

5 0

Answer:

Molality of solution = 0.973 m

Explanation:

Molality : It is defined as the moles of the solute per Kg mass of solvent.It is not temperature dependent.

Solute = Substance which is present in less quantity in the solution is called the solute. Here ,<u><em> Sucrose is the solute.</em></u>

Solvent = Substance which is present in more quantity is the solvent.<em><u> Here water is solvent.</u></em>

$Molality=\frac{moles\ of\ solute}{mass\ of\ solvent}$

Density = It is defined as the mass per unit volume.

$Density=\frac{mass}{Volume}$

Mass of Solute = 137.9 g

$Moles=\frac{mass}{Molar\ mass}$

Molar mass of sucrose =

$C_{12}H_{22}O_{11}$ = 12(mass of C)+22(mass of H)+11(mass of O)

= 12(12)+22(1)+11(16)

= 144+22+176

= 342 g/mol

$Moles=\frac{mass}{Molar\ mass}$

$Moles=\frac{137.9}{342}$

$Moles=0.403$

Moles = 0.403 moles

Mass of Solvent = 414.1 g (water)

$Molality=\frac{moles\ of\ solute}{mass\ of\ solvent(g)}(1000)$

$Molality =\frac{0.403}{414.1}\times 1000$

Molality = 0.973 m

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When 0.491 grams of a protein were dissolved in 44 mL of benzene at 24.4 degrees C, the osmotic pressure was found to be 50.9 to

Ira Lisetskai [31]

Answer:

4057.85 g/mol

Explanation:

Hello, the numerical procedure is shown in the attached file.

- In this case, since we don't have the density of the protein, we must assume that the volume of the solution is solely given by the benzene's volume, in order to obtain the moles of the solute (protein).

-Van't Hoff factor is assumed to be one.

Best regards.

4 0

3 years ago

The equilibrium constant Kp for the reaction (CH3),CCI (g) = (CH3),C=CH, (g) + HCl (g) is 3.45 at 500. K. (5.00 x 10K) Calculate

Karolina [17]

<u>Answer:</u> The value of $K_p$ for the reaction is 6.32 and concentrations of $(CH_3)_2C=CH,HCl\text{ and }(CH_3)_3CCl$ is 0.094 M, 0.094 M and 0.106 M respectively.

<u>Explanation:</u>

Relation of $K_p$ with $K_c$ is given by the formula:

$K_p=K_c(RT)^{\Delta ng}$

where,

$K_p$ = equilibrium constant in terms of partial pressure = 3.45

$K_c$ = equilibrium constant in terms of concentration = ?

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

T = temperature = 500 K

$\Delta n_g$ = change in number of moles of gas particles = $n_{products}-n_{reactants}=2-1=1$

Putting values in above equation, we get:

$3.45=K_c\times (0.0821\times 500)^{1}\\\\K_c=\frac{3.45}{0.0821\times 500}=0.084$

The equation used to calculate concentration of a solution is:

$\text{Molarity}=\frac{\text{Moles}}{\text{Volume (in L)}}$

Initial moles of $(CH_3)_3CCl(g)$ = 1.00 mol

Volume of the flask = 5.00 L

So, $\text{Concentration of }(CH_3)_3CCl=\frac{1.00mol}{5.00L}=0.2M$

For the given chemical reaction:

$(CH_3)_3CCl(g)\rightarrow (CH_3)_2C=CH(g)+HCl(g)$

Initial: 0.2 - -

At Eqllm: 0.2 - x x x

The expression of $K_c$ for above reaction follows:

$K_c=\frac{[(CH_3)_2C=CH]\times [HCl]}{[(CH_3)_3CCl]}$

Putting values in above equation, we get:

$0.084=\frac{x\times x}{0.2-x}\\\\x^2+0.084x-0.0168=0\\\\x=0.094,-0.178$

Negative value of 'x' is neglected because initial concentration cannot be more than the given concentration

Calculating the concentration of reactants and products:

$[(CH_3)_2C=CH]=x=0.094M$

$[HCl]=x=0.094M$

$[(CH_3)_3CCl]=(0.2-x)=(0.2-0.094)=0.106M$

Hence, the value of $K_p$ for the reaction is 6.32 and concentrations of $(CH_3)_2C=CH,HCl\text{ and }(CH_3)_3CCl$ is 0.094 M, 0.094 M and 0.106 M respectively.

8 0

3 years ago

Select the correct answer.

Minchanka [31]

Answer:

A. it is the lowest at low temperatures

Explanation:

It is true with respect to the kinetic energy of a molecule that the it is the lowest at low temperatures.

The kinetic energy of a molecule is the energy due to the motion of the particles within a substance.

Kinetic energy is directly proportional to the temperature of a substance.
The higher the temperature, the more the kinetic energy of the molecules within a system.
At low temperature, kinetic energy is the lowest.
At the highest temperature, kinetic energy is the highest

3 0

3 years ago

Read 2 more answers

Cadmium bromide is used in photography and lithography. What is the molality of a solution prepared by dissolving 45.38 g of CdB

mash [69]

Answer:

0.44 m is the molality

Explanation:

Molality means mol of solute in 1kg of solvent.

Solute → CdBr₂

Solvent → H₂O

Mass / Molar mass = 45.38 g / 272.21 g/m = 0.167 moles

1 g = 1x10⁻³ kg

375 g = 0.375 kg

0.167 m/0.375 kg = 0.44 m

6 0

3 years ago

Why is air called a homogeneous mixture?

Goryan [66]

Answer:

Air is called a homogeneous mixture because all of the elements that make up air (oxygen, nitrogen, argon, carbon dioxide etc.) are not able to be distinguished between when you look at air.

Explanation:

A heterogeneous mixture would be something like trail mix. You can look at the bowl of trail mix and pick out the raisins from the nuts from the chocolate. A homogeneous mixture is something where the individual elements can't be picked out by the plain eye. When you look at air you can't say oh that part is oxygen and that is argon when you are going on a walk. Air is a solution and thus you can't pick out each part.

8 0

3 years ago