Study Portal 6 – Chapter 6

Solutions

 

Q1.      Define solute, solvent and solution.

Ans.    Solute

The substance or component present in lesser amount in solution is called solute.

Solvent: – The substance or component present in greater amount in the solution is called solvent.

Solution: – A perfectly homogeneous mixture of two or more substance is called solution.

Q2.      Define unsaturated, saturated, super saturated, dilute and concentrated solutions.

  • Unsaturated solution: – The solution in which more quantity of the solute can be dissolved at room temperature is called unsaturated solution. If the addition of solute is continued, than a stage comes when the solvent refuses to accept the solute at that temperature at this stage, the solution formed is called a saturated solution.
  • Saturated solution: – The solution in which no more quantity of the solute can be dissolved at room temperature is called a saturated solution.
  • Super Saturated solution: – A solution which contains more amount of a solute in a particular amount of solvent then the saturated solution is called super saturated solution. Some of the solute remains undissolved and becomes visible as a separate phase.
  • Dilute solution: – A solution which contains very small amount of solute as compared to solvent is called dilute solution.
  • Concentrated solution: – A solution which contains a good amount of solute in a solvent is called a concentrated solution.

Q3.      Describe various types of solutions.

Ans.    There are nine different types of solutions which can be prepared by mixing together substance belonging to all the three states of matter. These substance in any physical state can serve as a solute or a solvent.

Q4.   What are the various units of percentage concentration?

Ans.    The amount of solute and solvent can be expressed in percentage composition in four different ways.

  • Mass by mass percent (M/M)
  • Mass by volume percent (M/V)
  • Volume by mass percent (V/M)
  • Volume by volume percent (V/V)
  • Mass by mass percent (M/M):- It is the mass of the solute dissolved per 100 parts by mass of solution. In this concentration unit, we know the mass of solute, mass of the solvent and the total mass of the solution.

Percentage by mass            =  (mass of solute x 100) / mass of solution

  • Mass by volume percent (M/V):- It is the mass of the solute dissolved per 100 parts by volume of solution.

Percentage of solution by M/V = (mass of solute ´ 100)/volume of

solution

  • Volume by mass percent (V/M):- It is the volume of a solute dissolved per 100 parts by mass of solution.

Percentage of solution by V/M      = (volume of solute ´ 100) / mass

of solution

  • Volume by volume percent (V/V):- It is the number of moles of solute per dm3 of the solution.

Molarity (M) = (mass of solute / molar mass of solute) ´

(1 / volume of solution in liter)

Number of moles of solute  =  mass of solute / molar mass

Molarity (M) = number of moles of solute / volume of solution in

liter

Q6.      What formula is used for dilution of a solution?

Ans.    For this purpose we should known the molarity of the solution to be diluted. Suppose we are provided with a solution of say 0.5 molarity and we have to prepare from it a solution of 0.1 molarity. Then solution needs dilution. For this purpose suitable volume of water is to be added to a known volume of concentrated solution of higher molarity using the following formula.

M1V1         =  M2V2

Where

M1           = molarity of dilute solution needed.

V1           = volume of dilute solution to prepare.

M2           = molarity of concentrated solution

V2           = volume of concentrated solution provided.

Q7.      Define Solubility.

Ans.    Solubility of a substance in a particular solvent at a definite temperature is the maximum amount of the solute in grams that can dissolve in 100 grams of the solvent to form a saturated solution.

Solute-solvent interaction during solubility:

“Like dissolves like”

It has been observed that non-polar covalent solutes are soluble in non-polar covalent solvents. While ionic and polar-solutes dissolve in polar solvent. This generalizes the solubility rule that “like dissolve like”

Effect of temperature on solubility:

We can divide the substance in three groups as far as solubility is concerned.

  • Those substance whose solubility is increased on increasing the temperature e.g. KNO3, AgNO3
  • Those substance whose solubility decreases on increasing the temperature e.g. Li2CO3, Ca (OH)2
  • The solubility of same substance is least affected by change in temperature e.g. NaCl.

Q8. What is comparison of the size of particles of a solution, suspension and colloids.

S.No. Property Solution Suspension colloids
1 Particle size Less than 1mμ More than 10μ Lies in the range 1mμ to 0.1μ
2 Nature Homogeneous Heterogeneous Heterogeneous
3 Separation
a Ordinary filter paper Not possible Possible Not possible
b Ultra filtration Not possible Possible Possible
4 Setting of solute particles Particles do not settle Particles settle under the effect of gravity Particles settle on centrifuging
5 Diffusion Take place rapidly No diffusion Slow
6 appearance transparent opaque Almost uniform transparent
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