Question:
What are the properties of a colloid?
Answer:
Properties of a colloid are:
- Heterogeneous nature: Colloid or Sol is heterogeneous in nature i.e. it can be seen only with a powerful microscope.
- Particle Size: Colloid particle size lies between 1nm (10-9 m) to 100 nm (10-7 m)
- Separation of colloidal particles by filtration: Colloidal particles cannot be separated from the mixture by the process of filtration. But, a special technique of separation known as centrifugation.
- Brownian Motion: When seen under microscope, the colloidal particles in a colloid are seen to be moving in a random fashion, called Brownian motion.
- Stability: They do not settle down when left undisturbed, that is, a colloid is quite stable.
- Tyndall effect: Colloid exhibit Tyndall effect. When a light is passed through sol kept in dark room, the path of light beam is visible. It is due to scattering of light by colloidal particles and this effect is called Tyndall effect.
- Electrophoresis: Man colloidal particles may have electrical charge (+ve or -ve) on them. When an electric current passes through a sol, colloid particles move towards opposite charged electrodes. This process is called electrophoresis.
Is Matter Around Us Pure?
Q 1.
Identify the following as mixture or compound.
(i) blood
(ii) common salt
(iii) sugar
(iv) brass
Q 2.
State the differences between compounds and mixtures.
Q 3.
What is a solution? What are the properties of a solution?
Q 4.
What are the characteristics exhibited by a pure substance?
Q 5.
What are the properties of suspensions?
Q 6.
What are the differences and similarities between concentration and solubility?
Q 7.
Name two properties of a substance to check its purity?
Q 8.
What are the reasons for separating the constituents of a mixture?
Q 9.
What factors affect the solubility of solvent and solute?
Q 10.
What are the physical states of dispersed phase and dispersion medium of a fog?
Q 11.
What are suspensions? Explain with an example.
Q 12.
To make a saturated solution, 36 g of sodium chloride is dissolved in 100 g of water at 293K. Find its concentration at this temperature.
Q 13.
What is meant by a pure substance?
Q 14.
How crystallization is better than evaporation?
Q 15.
Why air is a mixture not a compound? Give reasons.
Q 16.
What are the advantages of preparing solutions?
Q 17.
Name the elements are in liquid state at room temperature.
Q 18.
Based on the type of solvent, how solutions are classified?
Q 20.
Based on the amount of solute in the given solution, how solutions are classified?
Q 21.
What are the properties of a colloid?
Q 22.
How many elements are there which are in gaseous state at room temperature?
Q 23.
List the points of differences between homogeneous and heterogeneous mixtures.
Q 24.
A good method to separate alum (phitkari) from impure samples is
(a) Filtration
(b) Sedimentaion
(c) Crystallization
(d) Sublimation
Q 25.
What are the physical states of dispersed phase and dispersion medium of a cloud?
Q 26.
State three reasons why you think air is a mixture and water is a compound.
Q 27.
How much water should be mixed with 12 mL of alcohol so as to obtain 12 % alcohol solution ?
Q 28.
How will you separate iron pins from sand ?
Q 29.
Name the technique to separate
(i) butter from curd
(ii) salt from sea-water
(iii) camphor from salt
Q 30.
What are the various methods to express concentration of a solution?
Q 31.
Name the process you would use to separate a mixture of two miscible liquids (like acetone and water).
Q 32.
What is meant by Solubility?
Q 33.
What is Chromatography?
Q 34.
Fill in the following blanks with suitable words :
(a) An element is made up of only one kind of...........atoms
(b)Brine is a..........whereas alcohol is a.......
(c) Brass is an alloy which is considered a..........
(d) The three important metalloids are.............and...........
(e) The elements which are sonorous are called...............
Q 35.
What is difference between colloids and suspensions ?
Q 36.
21.5 g of sodium chloride dissolves in 60 g of water at 25°C. Calculate the solut water at that temperature.
Q 37.
What are non-aqueous solutions?
Q 38.
Choose one term from the following which includes the other three :
aerosol,
emulsion,
colloid,
sol
Q 39.
(a) What is a physical change ? Give two examples of physical changes.
(b) What is a chemical change ? Give two examples of chemical changes.
Q 40.
Which technique can be used to detect and identify traces of poison present in the stomach wash of a person ?
Q 41.
Which of the following is a mixture ?Salt, Air, Water, Alum, Sugar
Q 42.
Is air a mixture or a compound ? Give three reasons for your answer.
Q 43.
(a) What is meant by a solution ? Give two examples of solutions.
(b)What is a suspension ? Give two examples of suspensions.
(c)
Q 44.
Name the process you would use to separate a mixture of water and alcohol.
Q 45.
How are sol, solution and suspension different from each other?
Q 46.
Calculate the mass of glucouse and mass of water required to make 200g of 25% solution of glucouse.
Q 47.
Why solutions do not exhibit Tyndall effect?
Q 48.
Name a metal which is soft and a non-metal which is hard.
Q 49.
Which of the following is a sol ?
Shaving cream,
Milk,
Fog,
Soap solution,
Hairspray
Q 50.
Name one pair of substances whose mixture can be separated completely by distillation.
