ss 2 igcse chemistry 2nd term

What is the law that governs balancing chemical equations?

Theory questions

• Balancing Chemical Equations
  a) Explain the importance of balancing chemical equations.
  b) Balance the following equations:
  i) Fe + O₂ → Fe₂O₃
  ii) Al + HCl → AlCl₃ + H₂
  iii) Na + H₂O → NaOH + H₂

• Reactive Metals
  a) Define reactive metals.
  b) Explain why sodium is more reactive than iron.
  c) Describe an experiment to compare the reactivity of sodium and copper in water.

• Non-Reactive Metals
  a) Define non-reactive metals and give two examples.
  b) Why are gold and platinum considered non-reactive metals?
  c) List three important uses of non-reactive metals.

• Reactivity Series
  a) Define the reactivity series of metals.
  b) Arrange the following metals in order of decreasing reactivity:

  • Sodium, Copper, Magnesium, Iron, Zinc
    c) Explain why aluminium appears unreactive despite being a reactive metal.

• Reaction of Metals with Acids
  a) Describe what happens when magnesium reacts with hydrochloric acid.
  b) Write the balanced chemical equation for the reaction between zinc and sulfuric acid.

• Law of Conservation of Mass

• Law of Constant Composition

• Law of Definite Proportions

• Law of Multiple Proportions

Which of the following is the correctly balanced equation for the combustion of methane?

• CH₄ + O₂ → CO₂ + H₂O

• CH₄ + 2O₂ → CO₂ + 2H₂O

• CH₄ + O₂ → CO + H₂O

• 2CH₄ + O₂ → 2CO₂ + 2H₂O

How many oxygen molecules are needed to completely combust 2 moles of propane (C₃H₈)?

• 5

• 10

• 3

• 4

Balance the equation: Fe + O₂ → Fe₂O₃. What is the coefficient of Fe?

• 2

• 3

• 4

• 5

In the reaction: Na + H₂O → NaOH + H₂, what is the coefficient of NaOH when balanced?

• 1

• 2

• 3

• 4

What is a reactive metal?

• A metal that does not react with acids

• A metal that easily loses electrons to form positive ions

• A metal that is found only in free state in nature

• A metal that does not conduct electricity

Which of the following is the most reactive metal?

• Copper

• Iron

• Sodium

• Gold

Which of the following metals will NOT react with hydrochloric acid?

• Zinc

• Magnesium

• Copper

• Calcium

Which of these metals reacts most violently with water?

• Aluminium

• Iron

• Sodium

• Copper

Non-reactive metals are also called ____.

• Alkali metals

• Noble metals

• Transition metals

• Metalloids