Solutions
MCQs
What is solution ?
Answer: Solutions are homogeneous mixtures of two or more than two components.
Define the term –solubility ?
Answer: The maximum amount of a substance that can be dissolved in a fixed amount of solvent is called its solubility.
What is the effect of pressure on solubility of a gas ?
Answer: Solubility is directly related to pressure. So, solubility of a gas increases with increases of pressure.
State Henry’s Law.
Answer: Henry’s Law states that at a particular temperature, the solubility of a gas in a liquid is directly proportional to the pressure of the gas i.e solubility increases with increasing in pressure.
State Raoult’s Law.
Answer: Raoult’s Law states that for a solution of volatile liquids, the partial vapour pressure of each component in the solution is directly proportional to its mole fraction.
What are the factors on which vapour pressure depends ?
Answer: The factors on which vapour pressure depends are-
1. Temperature of the liquid.
2. Nature of the liquid.
The vapour pressure of solvent gets lowered, when a non- volatile solute is added to it. Why ?
Answer: When a non-volatile solute is added to a solvent, the surface area for escape of solvent molecules decreases and vapour pressure gets lowered.
Name two ways by which vapour pressure of a liquid can be lowered.
Answer: The two ways by which vapour pressure can be lowered are –
1. By decreasing the temperature.
2. By adding a non- volatile solute.
How does change in temperature changes the molarity and molality values ?
Answer: As the temperature increases, volume increases and molarity decreases whereas molality does not change with any change in temperature.
Define the term colligative properties ?
Answer: The properties which depends upon amount of solute and not upon the nature of solute are called colligative properties.
What are the possible deviations from ideal behaviors ?
Answer: There are two types of deviation from ideal behaviour possible. The first one is positive and the second one is negative deviations.
Give one example of each deviation ?
Answer: Positive deviation – ethanol and acetone.
Negative deviation – chloroform and acetone.
Why is the boiling point elevated when a non – volatile solute is dissolved in a liquid ?
Answer: When a non – volatile solute is added, the vapour pressure decreases and the solution is heated to a higher temperature, increasing the boiling point.
How is osmotic pressure of a solution related to its concentration ?
Answer: Osmotic pressure, π = CRT
C = concentration, R = gas constant and T= temperature
When does the measurement of colligative property leads to abnormal molecular mass ?
Answer: When the solute undergoes either association or disassociation abnormal molar mass is obtained.
When is the value of i less then unity ?
Answer: When the solute under goes association in solution, I is less then unity.
Name different types of colligative properties ?
Answer: There are four types of colligative properties they are given below–
a) Relative lowering of vapour pressure.
b) Elevation in boiling point.
c) Depression in freezing point.
d) Osmotic pressure.
Give the characteristics of ideal solution ?
Answer: An ideal solution is formed from two liquids only when –
a. They obey Raoult’s Law
b. ΔHmix = 0
c. ΔVmix = 0
d. The various inter molecular forces are identical.
A mixture of chlorobenzene and bromobenzene is a nearly an ideal solution but a mixture of chloroform and acetone is not Explain ?
Answer: Chlorobezene & bromobenzene both have similar structure and polarity. Therefore the various interactions (solute – solute, solvent – solvent & solute – solvent) are same whereas in chloroform and acetone initially there is no hydrogen bonding but after mixing solute solvent interactions (H –bond ) become stronger and solution deviates from ideal behaviour.
Define the term azeotrope ?
Answer: A solution at certain concentration when continues to boil at constant temperature without change in its composition in solution & in vapour phase is called an azeotrope.
Answer: Solutions are homogeneous mixtures of two or more than two components.
Define the term –solubility ?
Answer: The maximum amount of a substance that can be dissolved in a fixed amount of solvent is called its solubility.
What is the effect of pressure on solubility of a gas ?
Answer: Solubility is directly related to pressure. So, solubility of a gas increases with increases of pressure.
State Henry’s Law.
Answer: Henry’s Law states that at a particular temperature, the solubility of a gas in a liquid is directly proportional to the pressure of the gas i.e solubility increases with increasing in pressure.
State Raoult’s Law.
Answer: Raoult’s Law states that for a solution of volatile liquids, the partial vapour pressure of each component in the solution is directly proportional to its mole fraction.
What are the factors on which vapour pressure depends ?
Answer: The factors on which vapour pressure depends are-
1. Temperature of the liquid.
2. Nature of the liquid.
The vapour pressure of solvent gets lowered, when a non- volatile solute is added to it. Why ?
Answer: When a non-volatile solute is added to a solvent, the surface area for escape of solvent molecules decreases and vapour pressure gets lowered.
Name two ways by which vapour pressure of a liquid can be lowered.
Answer: The two ways by which vapour pressure can be lowered are –
1. By decreasing the temperature.
2. By adding a non- volatile solute.
How does change in temperature changes the molarity and molality values ?
Answer: As the temperature increases, volume increases and molarity decreases whereas molality does not change with any change in temperature.
Define the term colligative properties ?
Answer: The properties which depends upon amount of solute and not upon the nature of solute are called colligative properties.
What are the possible deviations from ideal behaviors ?
Answer: There are two types of deviation from ideal behaviour possible. The first one is positive and the second one is negative deviations.
Give one example of each deviation ?
Answer: Positive deviation – ethanol and acetone.
Negative deviation – chloroform and acetone.
Why is the boiling point elevated when a non – volatile solute is dissolved in a liquid ?
Answer: When a non – volatile solute is added, the vapour pressure decreases and the solution is heated to a higher temperature, increasing the boiling point.
How is osmotic pressure of a solution related to its concentration ?
Answer: Osmotic pressure, π = CRT
C = concentration, R = gas constant and T= temperature
When does the measurement of colligative property leads to abnormal molecular mass ?
Answer: When the solute undergoes either association or disassociation abnormal molar mass is obtained.
When is the value of i less then unity ?
Answer: When the solute under goes association in solution, I is less then unity.
Name different types of colligative properties ?
Answer: There are four types of colligative properties they are given below–
a) Relative lowering of vapour pressure.
b) Elevation in boiling point.
c) Depression in freezing point.
d) Osmotic pressure.
Give the characteristics of ideal solution ?
Answer: An ideal solution is formed from two liquids only when –
a. They obey Raoult’s Law
b. ΔHmix = 0
c. ΔVmix = 0
d. The various inter molecular forces are identical.
A mixture of chlorobenzene and bromobenzene is a nearly an ideal solution but a mixture of chloroform and acetone is not Explain ?
Answer: Chlorobezene & bromobenzene both have similar structure and polarity. Therefore the various interactions (solute – solute, solvent – solvent & solute – solvent) are same whereas in chloroform and acetone initially there is no hydrogen bonding but after mixing solute solvent interactions (H –bond ) become stronger and solution deviates from ideal behaviour.
Define the term azeotrope ?
Answer: A solution at certain concentration when continues to boil at constant temperature without change in its composition in solution & in vapour phase is called an azeotrope.
