Water

Question 1

Why did W. Ostwald believe that water is the elixir of life?

Answer 1

Because almost all chemical processes occurring in nature take place among solutions in water.

Question 2

What is the water cycle?

Answer 2

The water cycle is the circulation of water from the earth’s surface to the atmosphere and back through evaporation and as rain water.

Question 3

Give 3 proofs as to why water is a compound.

Answer 3

• Formed by combination of elements in a fixed ratio (o and H)
• The compound has properties differing from the elements
• The elements can be separated by chemical means and not physical

Question 4

Give 3 examples of treated water.

Answer 4

• Distilled water
• Chlorinated water
• Pipe borne water

Question 5

Why is water known as a universal solvent?

Answer 5

It can dissolve a large number of substances and gases.

Question 6

What is a solution?

Answer 6

A homogenous mixture formed when a solute dissolves in a solvent.

Question 7

Sugar solution is a mixture and not a compound. Explain

Answer 7

Sugar solution can be separated by physical means itself, therefore it is known as a mixture and not a compound.

Question 8

Give 3 characteristics of a true solution.

Answer 8

It is a clear, transparent and homogeneous mixture. The particles can pass through filter pores. The particles cannot be seen under a microscope and do not settle down.

Question 9

How can a saturated solution be converted to an unsaturated solution?

Answer 9

• By heating it slowly
• Adding more of the solvent

Question 10

How is a super saturated solution prepared?

Answer 10

When a saturated solution is prepared in boiling water and then is cooled, the excess nitre separates out from the hot solution and contains more of the solute dissolved and it can hold.

Question 11

Define Solubility

Answer 11

Ability of a solute to dissolve in a particular solvent. (Include even next point in your answer)

Question 12

Requirements to ensure uniformity of result

Answer 12

1. The amount if solvent is fixed
2. Temperature at which the solution is saturated is fixed.

Question 13

Formula for solubility

Answer 13

Solubility of a solute at t deg C =
(Insert Image)

Question 14

Steps involved in determining solubility of a solute at room temperature

Answer 14

Using KCl
1. Fill boiling tube with 100 ml of distilled water
2. Add potassium chloride crystals to it and stir slowly
3. Stir until all crystals dissolve
4.Repeat 2&3 until no more salt can dissolve
5. Pour saturated solution into dry test tube

To Check solubility of the solute. (Formula and calculations. Use image)