Please help chem homeworks

When 61.6 g of alanine (C3H7NO2) are dissolved in 1150. g of a certain mystery liquid X, the freezing point of the solution is 2

MrRissso [65]

Answer:

Explanation:

From the given information:

TO start with the molarity of the solution:

$= \dfrac{61.6 \ g \times \dfrac{1 \ mol \ C_3H_7 NO_3}{89.1 \ g} }{1150 \ g \times \dfrac{1 \ kg}{1000 \g }}$

= 0.601 mol/kg

= 0.601 m

At the freezing point, the depression of the solution is $\Delta \ T_f = T_{solvent}- T_{solution}$

$\Delta \ T_f = 2.9 ^0 \ C$

Using the depression in freezing point, the molar depression constant of the solvent $K_f = \dfrac{\Delta T_f}{m}$

$K_f = \dfrac{2.9 ^0 \ C}{0.601 \ m}$

$K_f = 4.82 ^0 C / m}$

The freezing point of the solution $\Delta T_f = T_{solvent} - T_{solution}$

$\Delta T_f = 7.3^ 0 \ C$

The molality of the solution is:

$= \dfrac{61.6 \ g \times \dfrac{1 \ mol \ NH_4Cl}{53.5 \ g} }{1150 \ g \times \dfrac{1 \ kg}{1000 \g }}$

Molar depression constant of solvent X, $K_f = 4.82 ^0 \ C/m$

Hence, using the elevation in boiling point;

the Vant'Hoff factor $i = \dfrac{\Delta T_f}{k_f \times m}$

$i = \dfrac{7.3 \ ^0 \ C}{4.82 ^0 \ C/m \times 1.00 \ m}$

$\mathbf {i = 1.51 }$

3 0

3 years ago

How can you use boiling point and solubility properties of a substance to seperate it from a mixture?

zhuklara [117]

Boiling point: the boiling point of compounds are all different. once a compound in a mixture reaches its boiling point, it will evaporate leaving behind the other compound that is yet to reach its boiling point.

if alcohol and water are mixed together, alcohol will boil first leaving behind water, hence water and alcohol have been separated

8 0

3 years ago

Find the energy required to melt the copper once it's reached the melting point.

belka [17]

The answer has to depend on the mass of the copper that you're trying to melt.

But there is a formula which you can calculate the energy required if you have the information of the mass. This formula requires the value called specific latent heat of fusion, which is the energy required to melt or freeze a specific mass of copper without changing its temperature but change its state.
$E = m l_{f}$
E is the total energy required, m is the mass, and lv is the specific latent heat of fusion of copper.

Usually, in questions, lv is given. But we can also look it up online which is around 205kJ kg^-1
this means, to melt or freeze a copper, we need to work the mass multiplied by 205kJ in order to calculate its total energy needed or released.

8 0

3 years ago

Which of the following is found in both a cell and a virus?

zloy xaker [14]

I dont know maybe b

5 0

3 years ago

Use Hess's Law to calculate the enthalpy change for the reaction

Marysya12 [62]

Answer:

ΔH = 125.94kJ

Explanation:

It is possible to make algebraic sum of reactions to obtain ΔH of reactions (Hess's law). In the problem:

1. 2W(s) + 3O2(g) → 2WO3(s) ΔH = -1685.4 kJ

2. 2H2(g) + O2(g) → 2H2O(g) ΔH = -477.84 kJ

-1/2 (1):

WO3(s) → W(s) + 3/2O2(g) ΔH = 842.7kJ

3/2 (2):

3H2(g) + 3/2O2(g) → 3H2O(g) ΔH = -716.76kJ

The sum of last both reactions:

WO3(s) + 3H2(g) → W(s) + 3H2O(g)

ΔH = 842.7kJ -716.76kJ

3 0

3 years ago