Solutions Test 41

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Solutions Test 41

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Weekly Quiz Competition

Question 1
1 / -0

Which of the following behaviour is true about the ideal binary liquid solution of liquids A and B if $$ P^0_A < P^0_B $$?

A
plot of $$ P_{total}| vs X_A $$ in non linear

B
plot of $$ P_{total}| vs X_B $$ is linear with +ve slope

C
plot of $$ P_{total}| vs X_B $$ is linear with slope = 0

D
plot of $$ P_{total}| vs X_B $$ is linear with -ve slope

Solution
Question 2
1 / -0

Benzene and toulene from an ideal solution, the vapour pressures of the benzene and toluene are 75 mm and 25 mm respectively at $$ 20^0 C $$ if the mole fractions of benzene and toluene in vapour are 0.75 and 0.25 respectively the vapour pressure of the ideal solution is

A
62.5 mm

B
50 mm

C
30 mm

D
40 m

Solution
Question 3
1 / -0

The ratio between lowering of vapour pressure of solution and mole fraction of solute is equal to

A
relative lowering of vapour pressure

B
vapour pressure of pure solvent

C
vapour pressure of solution

D
molar mass of solvent

Solution
Question 4
1 / -0

The vapour pressure of a soluiton of two liquids A ( $$ P^0 = 80 mm , X = 0.4 ) $$ and $$ B ( P^0 = 120mm ,X=0.6 ) $$ is found to be 100 mm, it shows that the solution exhibits

A
negative deviation from ideal behaviour

B
positive deviation from ideal behaviour

C
ideal behaviour

D
positive deviation at lower concentration

Solution
Question 5
1 / -0

Heptane and octane from ideal solution at 373 K the vapour pressure of the pure liquids are 106 kPa and 46 kpa respectively . what will be the vapour pressure, in bar of mixture of 30.0 g of heptane and 34.2 g of octane ?

A
76 bar

B
152 bar

C
1.52 bar

D
0.76 bar

Solution
Question 6
1 / -0

For an ideal solution of A and B , $$ Y_A $$ is the mole fraction of A in the vapour phase at equilibrium . which of the following plot should be linear ?

A
$$ P_{total} vs Y_A $$

B
$$ P_{total} vs Y_B $$

C
$$ \frac {1}{P_{total } } vs Y_A $$

D
$$ \frac {1}{P_{total} } vs \frac {1}{Y_A } $$

Solution
Question 7
1 / -0

An aqueous solution containing 0.25 moles of non-volatile but strong electrolytes solute X in 500 g water freeze at $$ -2.79^0 C .$$ The number of ions furnished in water per formula unit of X is $$ (K_f = 1.86 ) $$

A
1

B
2

C
3

D
4

Solution

Given:

Number of moles $$= 0.25\space moles$$
Mass of solvent $$= 500\space g$$
Depression in freezing temperature, $$\Delta T_f=2.79^{\circ}C$$
Freezing point depression constant, $$K_f=1.86$$
van't hoff factor $$=i$$

We know that,

$$\Delta T_f=i\times K_t\times m$$

So,
Molality, $$m=\dfrac{number\space of\space moles}{solvent\space in\space kg}=\frac{0.25\times 1000}{500}=0.5\space m$$

$$2.79=i\times 1.86\times 0.5$$

$$i=3$$

Therefore, the number of ions furnished = 3.

Hence, the correct option is (C).
Question 8
1 / -0

Under the condition of a similar temperature, which of the following solution will have, minimum vapour pressure?

A
0.1 M sugar

B
0.1 M $$NaCl$$

C
0.1 m $$ BaCl_2 $$

D
0.1 M $$ Al_2(SO_4)_3 $$
Question 9
1 / -0

A liquid solution is formed by mixing 10 moles of anline and 20 moles of phenol at a temperature where the vapour phenol are 90 and 897 mm Hg, respectively . The possible vapour pressure of solution at that temperature is ?

A
82 mm Hg

B
88 mm Hg

C
90 mm Hg

D
94 mm Hg

Solution
Question 10
1 / -0

A mixture contains 1 mole of volatile liquid $$ A (P^0_A = 100 mm Hg ) $$ and 3 moles of volatile liquid$$ B (P^0_B = 80 mm Hg ) $$ if the solution behaves ideally, the total vapour pressure of the distillate is

A
85 mm Hg

B
85.88 mm Hg

C
90 mm Hg

D
92 mm Hg

Solution

Mole fraction of A is $$X_A=\frac{1}{1+3}=0.25$$
Mole fraction of B is $$X_B=1-0.25=0.75$$

The expression for the total pressure of the solution is
$$P=P_A^0X_A+P_B^0X_B$$

Substitute values in the above expression
$$P=100\times 0.25+80\times 0.75=85$$ mm of Hg
Hence the correct answer is [A]