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CHEMISTRY FORM 1


i Common Chemistry Laboratory Chemicals
ii Common Chemistry Laboratory Apparatus
iii Safety in the Chemistry Laboratory
iv Why we should learn Chemistry
1. INTRODUCTION TO CHEMISTRY
2. SIMPLE CLASSIFICATION OF SUBSTANCES AND SEPERATION OF MIXTURES
3. ACIDS, BASES AND INDICATORS
4. AIR AND COMBUSTION
5. WATER AND HYDROGEN
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Water and Hydrogen: Reactions of metals with liquid water

5.0 Water and Hydrogen

5.2 Reactions of metals with liquid water

How does liquid water react with metals?


Materials and substances required
  1. Potassium, sodium, and calcium metals
  2. Trough containing water
  3. Litmus paper, tongs, knife

Set-up reactions of metals with liquid water high school chemistry

The experiment can be repeated using sodium metal. The solution formed in each case may be tested using litmus paper. Also, compare the vigour (how fast) of reactions for the three metals.


Observe the videos, reaction of potassium metal with cold water

(courtesy Youtube - Learn by Experimentation: Potassium and water by Carleton University)
and reaction of sodium metal with cold water.
(courtesy Youtube - reaction of sodium and water by North Carolina School of Science and Mathematics). Then answer Questions 5.2.


Questions 5.2(a)

  1. Describe what is observed when a small piece of potassium metal is added to water in a trough.
    1. State the observations when a fresh piece of sodium metal is added to water in a trough or beaker.
    2. Why does reaction with potassium need more space?
  2. Why would it not be advisable to use hot water or steam to study their reaction with potassium or sodium?
  3. Phosphorus is usually stored in water. Which liquid do you think would be suitable for storing potassium and sodium? Why?
    1. Reactions of potassium and sodium with water produce the same gas. Name the gas.
    2. How is the gas tested?
    1. What is the effect on phenolphthalein of the solution formed in these reactions? Why?
    2. How would this solution affect litmus paper?
  4. Name the substances produced by potassium and sodium and which affect litmus paper.

Answers to Questions 5.2(a)


For calcium, the reaction may be carried out in a test tube, and the gas tested using a burning splint. A small amount of freshly cleaned calcium turnings is used.


Set-up

Open the link, reaction of calcium with cold water

(courtesy Youtube - Calcium reacts with water by Sully Science) take observations and answer Questions 5.2(b)


Questions 5.2(b)

  1. Describe what is observed when calcium metal is added to water.
  2. Reactions between metals and water produce similar products. Name the products of reaction between calcium and water.
  3. How would the solution formed affect litmus paper?
  4. The same gas is produced in the reactions involving potassium and sodium.
    Write equations for the reactions between
    1. Potassium and water
    2. Sodium and water
    3. Calcium and water
  5. Complete the following general equation for the reactions between metal and water.
  6. Arrange the three metals in the order of their reactivity with water, beginning with the most reactive.

Answers to Questions 5.2(b)