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Maru [420]
3 years ago
8

An aqueous solution containing 16.5 g of an unknown molecular (nonelectrolyte) compound in 106.0 g of water was found to have a

freezing point of -1.9 ∘C. Calculate the molar mass of the unknown compound.
Chemistry
2 answers:
salantis [7]3 years ago
5 0

Answer : The molar mass of unknown compound is 152.38 g/mole

Explanation :

Depression in freezing point = 1.9^oC

Mass of unknown compound = 16.5 g

Mass of water = 106.0 g

Formula used :  

\Delta T_f=i\times K_f\times m\\\\\Delta T_f=i\times K_f\times\frac{\text{Mass of unknown compound}}{\text{Molar mass of unknown compound}\times \text{Mass of water in Kg}}

where,

\Delta T_f = depression in freezing point

i = Van't Hoff factor = 1 (for non-electrolyte)

K_f = freezing point constant for water = 1.86^oC/m

m = molality

Now put all the given values in this formula, we get

1.9^oC=1\times (1.86^oC/m)\times \frac{16.5g\times 1000}{\text{Molar mass of unknown compound}\times 106.0g}

\text{Molar mass of unknown compound}=152.38g/mole

Therefore, the molar mass of unknown compound is 152.38 g/mole

weqwewe [10]3 years ago
3 0

Answer: The molar mass of the unknown compound is 152 g/mol.

Explanation:

Depression in freezing point is given by:

\Delta T_f=i\times K_f\times m

\Delta T_f=T_f-^0T_f=(0-(-1.9)^0C=1.9^0C = Depression in freezing point

i= vant hoff factor = 1 (for non electrolyte)

K_f = freezing point constant = 1.86^0C/m

m= molality

\Delta T_f=i\times K_f\times \frac{\text{mass of solute}}{\text{molar mass of solute}\times \text{weight of solvent in kg}}

Weight of solvent (water)= 106.0 g = 0.106 kg

Molar mass of unknown non electrolyte = M g/mol

Mass of unknown non electrolyte added = 16.5 g

1.9=1\times 1.86\times \frac{16.5g}{M g/mol\times 0.106kg}

M=152g/mol

Thus the molar mass of the unknown compound is 152 g/mol.

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Tungsten (W) and chlorine (Cl) form a series of compounds with the following compositions:_______.
deff fn [24]

Answer:

WCl₂, WCl₄, WCl₅, WCl₆

Explanation:

Molar Mass of Tungsten = 184 g/mol

Mass of Chlorine = 35.5 g/mol

In the first compound;

Percentage of tungsten = 72.17 %

Upon solving;

72.17 % = 184

100 % = Total mass

Total mass of compound = 254.95g

Mass of chlorine = 254.95 - 184 = 70.95 (Dividing by 35.35; This is approximately 2 Chlorine atoms.

The Formular is WCl₂

In the second compound;

Percentage of tungsten = 56.45 %

Upon solving;

56.45 % = 184

100 % = Total mass

Total mass of compound = 325.95 g

Mass of chlorine = 325.95 - 184 = 141.95g (Dividing by 35.35; This is approximately 4 Chlorine atoms.

The Formular is WCl₄

In the third compound;

Percentage of tungsten = 50.91 %

Upon solving;

50.91 % = 184

100 % = Total mass

Total mass of compound = 361.42 g

Mass of chlorine =  361.42 - 184 = 177.42 (Dividing by 35.35; This is approximately 5 Chlorine atoms.

The Formular is WCl₅

In the fourth compound;

Percentage of tungsten = 46.39 %

Upon solving;

46.39 % = 184

100 % = Total mass

Total mass of compound = 396.64 g

Mass of chlorine = 396.64 - 184 = 212.64 (Dividing by 35.35; This is approximately 6 Chlorine atoms.

The Formular is WCl₆

4 0
4 years ago
What evidence always shows that a chemical change has happened?
TEA [102]

Answer:

B. A new substance is produced.

Explanation:

In chemical changes, you will always have a new end product from the reactants that were used within the process.

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5 0
3 years ago
Which set of terms best defines what affects kinetic energy and potential energy, respecrively<br>​
xeze [42]
The correct answer is velocity and height!
7 0
3 years ago
Sodium has an atomic number of 11 and has a net charge of 0. When sodium combines with chlorine, it has a net charge of +1. Why?
lana [24]
Sodium has an atomic number 11, it means there are 11 electrons in sodium atom and has a net charge zero what when it combines with chlorine it loses one electron and get charge of +1. when and atom loses an electron it gets positive charge and when atom gains electron it gets negative charge. chlorine makes an anion and sodium makes cation and they are oppositely charged so they react with each other.
7 0
4 years ago
Read 2 more answers
Grams needed to prepare the solution
erastovalidia [21]

Answer:

grams of solute = 31.5 g

Explanation:

Given data:

Grams of solute = ?

%m/v  = 3%

Volume = 1050 mL

Solution:

grams of solute = 3 g of NH₄Cl / 100 mL × 1050 mL

grams of solute = 0.03 g × 1050  

grams of solute = 31.5 g

8 0
3 years ago
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