Metals 5 Self Check

Which carbonate decompose the fastest?

• Calcium carbonate

• Copper (II) carbonate

• Sodium carbonate

• Zinc carbonate

Answer explanation

The more reactive the metal, the more thermally stable the metal carbonate.

Which carbonate cannot be decomposed at all?

• Calcium carbonate

• Lead (II) carbonate

• Sodium carbonate

• Zinc carbonate

Answer explanation

Sodium is a very reactive metal hence its carbonate is very stable.

Which metal is the most reactive

• Metal X

• Metal Y

• Metal Z

Answer explanation

The longer it takes to decompose, the more stable the metal carbonate and therefore the most reactive metal.

The carbonates of metals X and Y were heated in air. The carbonate of metal X changed colour from green to black when heated and carbon dioxide was given off. The carbonate of metal Y did not decompose. Study the statements in the picture. Which statements are correct?

• All 3 statements

• 1 and 2 only

• 1 and 3 only

• 2 and 3 only

Answer explanation

Carbonate of metal X decompose but carbonate of metal Y did not. Hence metal Y is more reactive than metal X.

All carbonates react with acid to produce carbon dioxide, salt and water.

Transition element formed coloured compounds.

Iron (II) carbonate, zinc carbonate and magnesium carbonate decompose when heated. Which is the correct order for their decomposition? (Arranged from highest temperature to lowest temperature)

• Iron (II) carbonate, magnesium carbonate, zinc carbonate

• Magnesium carbonate, zinc carbonate, iron (II) carbonate

• Zinc carbonate, magnesium carbonate, iron (II) carbonate

• Magnesium carbonate, iron (II) carbonate, zinc carbonate

Answer explanation

Magnesium is more reactive than zinc which is more reactive than iron.

The carbonates of many metallic elements decomposed when heated. The gas produced during the decomposition of a metal carbonate is

The chemical test used to test for the gas produced during the decomposition of a metal carbonate is to use

Write down the equation for the decomposition of the copper (II) carbonate.

Answer explanation

CuCO3 -> CuO + CO2

A student investigates the decomposition of five different metal carbonates by heating 0.01 mol samples of each carbonate. She measures the time it takes for 100 cm3 of gas to be collected in a gas syringe. The diagram shows her results.

The student used calcium carbonate, copper (II) carbonate, iron (II) carbonate, potassium carbonate and zinc carbonate.

Identify each metal V, W, X, Y Z.

Answer explanation

U - Copper

V - Zinc

X - Calcium

Y - Potassium

Z - Iron