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SS1: CHEMISTRY - 1ST TERM

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  1. Introduction to Chemistry and Laboratory Apparatus | Week 1
    5 Topics
    |
    1 Quiz
  2. Nature of Matter | Week 2
    3 Topics
    |
    1 Quiz
  3. Separation Techniques I | Week 3
    1 Topic
  4. Separation Techniques II | Week 4
    5 Topics
    |
    1 Quiz
  5. Particulate Nature of Matter I | Week 5
    5 Topics
    |
    1 Quiz
  6. Particulate Nature of Matter II | Week 6
    9 Topics
    |
    1 Quiz
  7. Symbols, Formulae & Oxidation Number | Week 7
    7 Topics
    |
    1 Quiz
  8. Laws of Chemical Combination | Week 8
    4 Topics
    |
    1 Quiz
  9. Chemical Equation & Chemical Combination (Chemical Bonding) I | Week 9
    4 Topics
    |
    1 Quiz
  10. Chemical Combination (Chemical Bonding) II | Week 10
    4 Topics
    |
    1 Quiz
  11. Chemical Combination (Chemical Bonding) III & Shapes of Covalent Molecules | Week 11
    3 Topics
    |
    1 Quiz

Quizzes




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Topic Content:

  • Why Atoms Combine
  • Systematic Arrangement of Elements in the Periodic Table
  • Periodic table of the 1st Twenty Elements

Why Atoms Combine:

In our discussion on atomic structure, the atom was described as a neutral particle. The number of positively charged particles (protons) in the nucleus is balanced by that of negatively charged particles (electrons) revolving around the nucleus.

Atoms are rarely found in nature as free elements apart from the noble (rare) gases: helium, neon, argon, etc.

 

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Theory Question 1

(a) State the law of (i) definite proportion (ii) conservation of matter.

Answer:

(i) The law of definite proportion states that all pure samples of the same chemical compound contain the same elements combined in the same proportion by mass.

(ii) The law of conservation of matter states that in an ordinary chemical reaction, matter can neither be created nor destroyed.

 

(b) Which of these laws govern the balancing of chemical equation?

Answer:

Law of conservation of matter (mass)

Theory Question 2

Write the balanced equation for each of the following reactions:

(a)  Zinc + hydrochloric acid → Zinc chloride + hydrogen

Answer:  Zn(s) + 2HCl(aq)  → ZnCl2 + H2(g)

(b) Calcium + water →  Calcium hydroxide + hydrogen

Answer: 2Ca(s) + 2H2O(aq)  → 2CaOH(s) + H2(g)

Theory Question 3

Balance the following chemical equations

(a) CaCO3 + HCl →   CaCl2 + H2O + CO2

Answer: CaCO3 + 2HCl → CaCl2 + H2O + CO2

 

(b)  Na + O2 →  Na2O

Answer:  4Na + O2 → 2Na2O

 

(c)  NH3 + O2 → NO + H2O

Answer: 4NH3 + 3O2 → 2NO + 6H2O

 

(d) KClO3 →  KCl + O2

Answer:  2KClO3 →  2KCl + 3O2

 

(e) C2H6 + O2 → CO2 + H2O

Answer:  2C2H6 + 7O2 → 4CO2 + 6H2O

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