Define thermal decomposition .

A thermal decomposition is a reaction in which a substance breaks down into simpler substances due to the action of heat.

What two products form when a metal carbonate undergoes thermal decomposition?

When a metal carbonate undergoes thermal decomposition, it forms a metal oxide and carbon dioxide gas.

True or False? Copper(II) carbonate is more thermally stable than potassium carbonate.

False. Potassium carbonate is more thermally stable because potassium is a more reactive metal than copper. The more reactive the metal, the more stable its carbonate. Potassium carbonate decomposes at 1200 °C, while copper(II) carbonate decomposes at only 290 °C.

When copper(II) carbonate is heated, the green powder turns .......... as .......... is produced, and .......... gas is released.

When copper(II) carbonate is heated, the green powder turns black as copper(II) oxide is produced, and carbon dioxide gas is released.

How can you test for carbon dioxide gas produced during the thermal decomposition of a metal carbonate?

You test for carbon dioxide by bubbling the gas through limewater . A positive result is the limewater turning milky or cloudy.

True or False? The more reactive the metal, the more thermally stable its carbonate.

True. Metal carbonates containing a very reactive metal require the most heat to decompose, making them the most thermally stable. For example, potassium carbonate (from a highly reactive metal) decomposes at 1200 °C, whereas copper(II) carbonate decomposes at just 290 °C.

Define thermal stability (of a metal carbonate).

Thermal stability is a measure of how strongly a metal carbonate must be heated before it decomposes. The higher the temperature required, the greater the thermal stability.

The equation for the thermal decomposition of copper(II) carbonate is: CuCO 3 (s) → .......... (s) + .......... (g).

The equation for the thermal decomposition of copper(II) carbonate is: CuCO 3 (s) → CuO (s) + CO 2 (g).

What is the purpose of limewater in the thermal stability of carbonates practical?

The purpose of limewater in the practical is to detect carbon dioxide . When the metal carbonate decomposes, the carbon dioxide produced turns the limewater milky .

What is limewater used for in the thermal stability of carbonates practical?

Limewater is a solution of calcium hydroxide used to test for carbon dioxide. It turns milky when carbon dioxide is passed through it, indicating that the metal carbonate has decomposed.

True or False? In the thermal stability practical, a shorter time for limewater to turn milky means the carbonate is more thermally stable.

False. A shorter time means the carbonate decomposed more quickly, so it is less thermally stable . The most thermally stable carbonate takes the longest to decompose, meaning the limewater takes longer (or never) turns milky.

In the thermal stability practical, the limewater did not change colour when .......... carbonate was heated, showing it is the .......... thermally stable of the three tested.

In the thermal stability practical, the limewater did not change colour when sodium carbonate was heated, showing it is the most thermally stable of the three tested.

In the thermal stability practical, why did the limewater not turn milky when sodium carbonate was heated?

The limewater did not turn milky because the Bunsen burner flame does not reach a high enough temperature to decompose sodium carbonate. Sodium is a highly reactive metal, making its carbonate very thermally stable .

True or False? Copper(II) carbonate decomposed faster than calcium carbonate in the thermal stability practical.

True. Copper(II) carbonate is less thermally stable than calcium carbonate and decomposes more easily on heating. This is because copper is less reactive than calcium , so its carbonate requires less energy to decompose.

Describe an alternative method to using limewater for comparing the thermal stability of metal carbonates.

An alternative method is to record the change in mass of the boiling tube during heating. The greater the loss in mass, the more carbon dioxide has been released, so the carbonate is less thermally stable .

In the thermal stability practical, the order of stability from least to most stable is: .......... , .......... , .......... .

In the thermal stability practical, the order of stability from least to most stable is: copper(II) carbonate , calcium carbonate , sodium carbonate .

Quicklime is the common name for calcium oxide (CaO), produced by the thermal decomposition of limestone (calcium carbonate).

What are the chemical name and formula for slaked lime?

The chemical name for slaked lime is calcium hydroxide , and its formula is Ca(OH) 2 .

In the limestone cycle, calcium oxide reacts with water to form .......... This reaction is .......... .

In the limestone cycle, calcium oxide reacts with water to form calcium hydroxide . This reaction is exothermic .

True or False? Limewater is a solution of calcium oxide in water.

False. Limewater is a solution of calcium hydroxide , Ca(OH) 2 (aq). It is made by dissolving slaked lime (calcium hydroxide) in water, not calcium oxide.

What observation is made when carbon dioxide is bubbled through limewater in step 4 of the limestone cycle?

When carbon dioxide is bubbled through limewater, the solution turns milky or cloudy . This is because a suspension of calcium carbonate is formed.

The equation for step 1 of the limestone cycle is: CaCO 3 (s) → .......... (s) + .......... (g).

The equation for step 1 of the limestone cycle is: CaCO 3 (s) → CaO (s) + CO 2 (g).

True or False? When calcium carbonate is strongly heated, the solid glows brightly and turns crumbly.

True. Heating calcium carbonate causes it to glow brightly and then become crumbly as it thermally decomposes into calcium oxide and carbon dioxide .

Why must limewater be filtered before use in step 3 of the limestone cycle?

Limewater must be filtered because calcium hydroxide is only sparingly soluble in water. Filtering removes any undissolved solid, leaving a clear solution of calcium hydroxide.

How is cement made from limestone?

Cement is made by heating powdered limestone with clay. It is used as an ingredient in mortar (which joins bricks) and in concrete.

True or False? Limestone can be used to neutralise acidic soil in agriculture.

True. Limestone, along with quicklime and slaked lime , can be spread on acidic soil to neutralise it. This allows crops to grow more effectively.

Limestone is used in the manufacture of iron to remove .......... impurities from the .......... .

Limestone is used in the manufacture of iron to remove acidic impurities from the blast furnace .

Quarrying is a method of extracting rock from the ground in which the rock is blasted out of huge open pits.

Give two economic advantages of quarrying limestone for a local community.

Two economic advantages are that quarrying: Creates more local jobs Supports the local economy It may also lead to improvements in the local road system.

True or False? Dust from limestone quarrying can contribute to increased rates of respiratory conditions in nearby residents.

True. Dust produced by blasting and transport during quarrying can be inhaled by local residents. This can lead to increased numbers of respiratory conditions such as asthma .

Concrete is made by mixing .......... with sand, .......... and crushed rock.

Concrete is made by mixing cement with sand, water and crushed rock.

Give two environmental disadvantages of quarrying limestone.

Two environmental disadvantages are: The destruction of the landscape and wildlife habitats . Dust and vehicle pollution which can harm the health of local residents.

GCSEChemistryWJECFlashcards1. Chemical Substances, Reactions & Essential Resources1.6 Limestone

1.6 Limestone (WJEC GCSE Chemistry): Flashcards

Exam code: 3410

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Cards in this collection (32)

Define thermal decomposition.
A thermal decomposition is a reaction in which a substance breaks down into simpler substances due to the action of heat.
What two products form when a metal carbonate undergoes thermal decomposition?
When a metal carbonate undergoes thermal decomposition, it forms a metal oxide and carbon dioxide gas.
True or False?
Copper(II) carbonate is more thermally stable than potassium carbonate.
False.
Potassium carbonate is more thermally stable because potassium is a more reactive metal than copper. The more reactive the metal, the more stable its carbonate. Potassium carbonate decomposes at 1200 °C, while copper(II) carbonate decomposes at only 290 °C.
When copper(II) carbonate is heated, the green powder turns .......... as .......... is produced, and .......... gas is released.
When copper(II) carbonate is heated, the green powder turns black as copper(II) oxide is produced, and carbon dioxide gas is released.
How can you test for carbon dioxide gas produced during the thermal decomposition of a metal carbonate?
You test for carbon dioxide by bubbling the gas through limewater. A positive result is the limewater turning milky or cloudy.
True or False?
The more reactive the metal, the more thermally stable its carbonate.
True.
Metal carbonates containing a very reactive metal require the most heat to decompose, making them the most thermally stable. For example, potassium carbonate (from a highly reactive metal) decomposes at 1200 °C, whereas copper(II) carbonate decomposes at just 290 °C.
Define thermal stability (of a metal carbonate).
Thermal stability is a measure of how strongly a metal carbonate must be heated before it decomposes. The higher the temperature required, the greater the thermal stability.
The equation for the thermal decomposition of copper(II) carbonate is: CuCO₃ (s) → .......... (s) + .......... (g).
The equation for the thermal decomposition of copper(II) carbonate is: CuCO₃ (s) → CuO (s) + CO₂ (g).
What is the purpose of limewater in the thermal stability of carbonates practical?
The purpose of limewater in the practical is to detect carbon dioxide. When the metal carbonate decomposes, the carbon dioxide produced turns the limewater milky.
What is limewater used for in the thermal stability of carbonates practical?
Limewater is a solution of calcium hydroxide used to test for carbon dioxide. It turns milky when carbon dioxide is passed through it, indicating that the metal carbonate has decomposed.
True or False?
In the thermal stability practical, a shorter time for limewater to turn milky means the carbonate is more thermally stable.
False.
A shorter time means the carbonate decomposed more quickly, so it is less thermally stable. The most thermally stable carbonate takes the longest to decompose, meaning the limewater takes longer (or never) turns milky.
In the thermal stability practical, the limewater did not change colour when .......... carbonate was heated, showing it is the .......... thermally stable of the three tested.
In the thermal stability practical, the limewater did not change colour when sodium carbonate was heated, showing it is the most thermally stable of the three tested.
In the thermal stability practical, why did the limewater not turn milky when sodium carbonate was heated?
The limewater did not turn milky because the Bunsen burner flame does not reach a high enough temperature to decompose sodium carbonate. Sodium is a highly reactive metal, making its carbonate very thermally stable.
True or False?
Copper(II) carbonate decomposed faster than calcium carbonate in the thermal stability practical.
True.
Copper(II) carbonate is less thermally stable than calcium carbonate and decomposes more easily on heating. This is because copper is less reactive than calcium, so its carbonate requires less energy to decompose.
Describe an alternative method to using limewater for comparing the thermal stability of metal carbonates.
An alternative method is to record the change in mass of the boiling tube during heating. The greater the loss in mass, the more carbon dioxide has been released, so the carbonate is less thermally stable.
In the thermal stability practical, the order of stability from least to most stable is: .........., .........., ...........
In the thermal stability practical, the order of stability from least to most stable is: copper(II) carbonate, calcium carbonate, sodium carbonate.
What is quicklime?
Quicklime is the common name for calcium oxide (CaO), produced by the thermal decomposition of limestone (calcium carbonate).
What are the chemical name and formula for slaked lime?
The chemical name for slaked lime is calcium hydroxide, and its formula is Ca(OH)₂.
In the limestone cycle, calcium oxide reacts with water to form .......... This reaction is ...........
In the limestone cycle, calcium oxide reacts with water to form calcium hydroxide. This reaction is exothermic.
True or False?
Limewater is a solution of calcium oxide in water.
False.
Limewater is a solution of calcium hydroxide, Ca(OH)₂ (aq). It is made by dissolving slaked lime (calcium hydroxide) in water, not calcium oxide.
What observation is made when carbon dioxide is bubbled through limewater in step 4 of the limestone cycle?
When carbon dioxide is bubbled through limewater, the solution turns milky or cloudy. This is because a suspension of calcium carbonate is formed.
The equation for step 1 of the limestone cycle is: CaCO₃ (s) → .......... (s) + .......... (g).
The equation for step 1 of the limestone cycle is: CaCO₃ (s) → CaO (s) + CO₂ (g).
True or False?
When calcium carbonate is strongly heated, the solid glows brightly and turns crumbly.
True.
Heating calcium carbonate causes it to glow brightly and then become crumbly as it thermally decomposes into calcium oxide and carbon dioxide.
Why must limewater be filtered before use in step 3 of the limestone cycle?
Limewater must be filtered because calcium hydroxide is only sparingly soluble in water. Filtering removes any undissolved solid, leaving a clear solution of calcium hydroxide.
How is cement made from limestone?
Cement is made by heating powdered limestone with clay. It is used as an ingredient in mortar (which joins bricks) and in concrete.
True or False?
Limestone can be used to neutralise acidic soil in agriculture.
True.
Limestone, along with quicklime and slaked lime, can be spread on acidic soil to neutralise it. This allows crops to grow more effectively.
Limestone is used in the manufacture of iron to remove .......... impurities from the ...........
Limestone is used in the manufacture of iron to remove acidic impurities from the blast furnace.
What is quarrying?
Quarrying is a method of extracting rock from the ground in which the rock is blasted out of huge open pits.
Give two economic advantages of quarrying limestone for a local community.
Two economic advantages are that quarrying:
1. Creates more local jobs
2. Supports the local economy
It may also lead to improvements in the local road system.
True or False?
Dust from limestone quarrying can contribute to increased rates of respiratory conditions in nearby residents.
True.
Dust produced by blasting and transport during quarrying can be inhaled by local residents. This can lead to increased numbers of respiratory conditions such as asthma.
Concrete is made by mixing .......... with sand, .......... and crushed rock.
Concrete is made by mixing cement with sand, water and crushed rock.
Give two environmental disadvantages of quarrying limestone.
Two environmental disadvantages are:
1. The destruction of the landscape and wildlife habitats.
2. Dust and vehicle pollution which can harm the health of local residents.

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