3.4 - Limestone

Question 1

What are the word equations for calcium carbonate, sodium carbonate and copper carbonate?

Answer 1

Calcium carbonate = calcium oxide + carbon dioxide
Sodium carbonate = sodium oxide + carbon dioxide
Copper carbonate = copper oxide + carbon dioxide

Question 2

What are the symbol equations for decomposition of carbonates?

Answer 2

CACO3 = CaO + CO2
NaCO3 = NaO + CO2
CuCO3 = CuO + CO2

Question 3

How can the speed of decomposition be measured?

Answer 3

By timing the colour change of limestone

Question 4

What are the observations after heating sodium carbonate?

Answer 4

Still white, no gas, hard to decompose

Question 5

What are the observations after heating copper carbonate?

Answer 5

Turns from green to black, carbon dioxide, easy to decompose

Question 6

Why does calcium decompose easily than sodium?

Answer 6

Because it is less reactive. The more reactive the metal the more stable the carbonate

Question 7

What is the 1st stage to create limewater from limestone?

Answer 7

1. Roast for 20 minutes

- the limestone glows and becomes crumbly. It decomposes to calcium oxide

Question 8

2. What is the 2nd stage to create limewater from limestone?

Answer 8

2. Add a few drops of water
   The calcium oxide (quicklime) sizzles and releases steam
   -this forms calcium hydroxide (slaked lime)
   -reaction is exothermic
   CAO + H20 = Ca(OH)2

Question 9

What is the 3rd stage to get limewater from limestone?

Answer 9

3. Add excess water
   - the slaked lime dissolves a little in water
   - excess water is added to form an alkaline solution called limewater

Question 10

Word and symbol equation for the reaction of lime water with carbon dioxide

Answer 10

Calcium hydroxide + carbon dioxide = calcium carbonate + water
Ca(OH)2 + Co2 = CaCO3 + H20

Question 11

What are the raw material uses of limestone?

Answer 11

• used in iron and steel production
• used to make cement
• used for roads as it is strong
• used to neutralise and raise pH of acidic salts used to make glass

Question 12

What are the social, environmental and economic effects of quarrying?

Answer 12

Social:

• noise due to rock blasting
• creates jobs

Eco:
-boosts economy

Environ:

• destroys wildlife
• increased traffic with heavy lorries

Question 13

How to test for limewater?

Answer 13

Pass carbon dioxide through it and see if it goes milky

Question 14

What is thermal decomposition?

Answer 14

When a compound splits into two or more by heat