4: Rocks and Minerals Flashcards
What is the name of the ore containing aluminium oxide?
Bauxite
What is the name of the ore containing mercury sulphide?
Cinnabar
What is the name of the ore containing iron oxide?
Haematite
What is the name of the ore containing copper carbonate?
Malachite
List two metal compounds from which the metal can be separated through heating the ore alone.
Mercury sulphide and silver oxide
What is limestone?
Limestone is one of the most common types of rock found on the surface of the Earth. It is a rock composed largely of the mineral calcite, which is composed of calcium carbonate.
List 5 usages of limestone.
- For construction of buildings and roads
- Making glass
- Neutralising sulphur dioxide in flue gas from power stations
- Making cement
- Neutralising acidity in soil and lakes
List 2 usages of quicklime.
- Making steel from iron
- Neutralising acidity in soil
List 2 usages of slaked lime.
- Neutralising acidity in soil and lakes
- Making bleaching powder
What is the word equation for the reaction from limestone to quicklime?
Calcium carbonate heat -> calcium oxide + carbon dioxide
What is the word equation for the reaction from quicklime to slaked lime and limewater?
Calcium oxide + water -> calcium hydroxide
What is the word equation for the reaction from clear limewater to milky limewater?
Calcium hydroxide + carbon dioxide -> calcium carbonate + water
What is the word equation for the reaction of limewater turning from milky to clear?
Calcium carbonate + water + carbon dioxide -> calcium hydrogencarbonate
What is the word equation for the reaction between hydrochloric acid and limestone?
Calcium carbonate + dilute hydrochloric acid -> calcium chloride + water + carbon dioxide
Why does the size of limestone chips shrink when dilute hydrochloric acid is added to them?
Calcium carbonate reacts with dilute hydrochloric acid to produce calcium chloride, which is soluble in water. Therefore, the size of calcium carbonate appears to shrink.
What is the definition of effervescence?
Bubbling / fizzing
What is the test for metal carbonate?
- Add the solid into some dilute acid.
- Stopper the tube immediately with a stopper connected with a delivery tube. Put the other end of the delivery tube into a test tube of limewater.
- Observe if there is any colour change for the limewater.
If the solid is a metal carbonate, there should be effervescence and the limewater will turn from colourless to milky.
What is the relationship between chalk, limestone, and marble?
Chalk is formed when calcium carbonate from the shells of sea creatures sink to the bottom and receive pressure and heat.
Higher pressure and heat causes chalk to turn into much harder limestone.
If buried limestone in an active part of Earth’s crust suffers huge increases in pressure and temperature, it turns into marble.
Among the three rocks, chalk is the softest while marble is the hardest.
What is weathering?
Weathering is the process where rock is dissolved, worn away or broken down into smaller and smaller pieces. Once the rock has been weakened and broken up by weathering, it is ready for erosion. Erosion happens when weathered rock materials are moved to another place by ice, water, wind, or gravity.
How are limestone caves formed?
- When rain falls, rainwater absorbs carbon dioxide in the air to form carbonic acid
water + carbon dioxide -> carbonic acid - The acid in the rainwater reacts with calcium carbonate in the limestone to produce calcium hydrogencarbonate solution, and thus dissolves the limestone.
calcium carbonate + carbonic acid -> calcium hydrogencarbonate - Rainwater slowly dissolves the limestone along the cracks in the rock. Over millions of years, underground limestone caves are formed.
What is the procedure of the chloride test?
- Dissolve the sample in water.
- Add excess dilute nitric acid.
- Add an aqueous solution of silver nitrate.
A white precipitate will be produced if the solid sample is a chloride.
