Questão | Responda |
What is limestone mainly made up of? | Calcium Carbonate CaCO3 |
How is limestone formed? | From the remains of tiny animals and plants that lived in the sea millions of years ago. |
How do we obtain limestone? | We dig it out of the ground in quarries/ Quarrying. |
What is limestone mostly used for? | Building materials |
How do we make cement? | We heat powdered limestone with powdered clay in a kiln. |
How do we make mortar? | We mix cement and sand with water. |
How do we make concrete? | We mix aggregate, cement and sand with water. |
Define: Aggregate | Crushed rocks or small stones |
Define: Thermal Decomposition | Breaking down a chemical by heating it. |
Calcium carbonate is made up of which ions? | Ca 2+ and CO3 2- ions |
What are the products of thermally decomposing CaCO3? | Calcium oxide CaO and Carbon dioxide CO2 |
What do we use to make calcium oxide? | Rotary lime kiln |
How do we use a rotary lime kiln to make calcium oxide? | We fill it with crushed limestone and heat it with steam. Calcium oxide comes out at the bottom. Waste gases leave at the top. |
What is the point of having a rotating drum in a rotary lime kiln? | It makes sure the limestone is thoroughly mixed with the steam. It helps the limestone to decompose completely. |
What damages buildings and statues made out of limestone? | Acid rain |
Why does acid rain damage buildings and statues made out of limestone? | Calcium carbonate reacts with the acid and gives off a gas. |
What is the test for carbon dioxide? | Limewater (calcium hydroxide) turns cloudy because tiny solid particles of insoluble calcium carbonate are formed as a precipitate. |
What happens in the test for carbon dioxide? Give an equation. | Calcium Hydroxide + Carbon Dioxide -> Calcium Carbonate + Water. Ca(OH)2 + CO2 -> CaCO3+ H2O |
Finish the word equation: Metal carbonate + acid -> | Salt + Water + Carbon Dioxide. |
Which other metals react in the same way as Calcium? | Group 2 metals |
Which metal carbonates cannot be decomposed using a Bunsen burner? Why? | Sodium carbonate Potassium carbonate They need higher temperatures. They are more reactive than the other carbonates. |
Go through the steps of the Limestone Cycle. | |
What do we use Calcium Hydroxide for? | Farmers use it to neutralise acidic soils. It is used to neutralise acidic waste gases in industry before releasing them into the atmosphere. |
How does Calcium Hydroxide neutralise acidic soils? | Neutralisation reaction. It is an alkali. Raises pH of the soil. Produces a calcium salt and water. |
What does mortar do? | Holds building materials together. |
How does mortar work? | The calcium hydroxide reacts with carbon dioxide in the air and forms calcium carbonate. Calcium Hydroxide + Carbon Dioxide -> Calcium Carbonate + Water Ca(OH)2 + CO2 -> CaCO3 + H2O |
What is the difference between lime mortar and modern mortar? | Lime mortar is made by mixing CALCIUM HYDROXIDE and water and sand. Modern mortar is made up of CEMENT, water and sand. |
What is Portland cement? | Cement that is used in the modern day. It is made from a mixture of limestone, clay and other minerals. They are heated and then ground up into a fine powder. |
What is reinforced concrete? | Concrete is poured around steel rods/ bars/ mesh/ glass. It is good at resisting forces that pull it apart. |
What are the advantages of quarrying limestone? | 1. Provides local jobs / helps local economy. 2. It is a valuable natural resource. 3. It is in high demand. 4. Helps raise awareness about poor infrastructure. 5. Huge craters left behind can be made into reservoirs/ landfill sites/ replanted. |
What are the disadvantages of quarrying limestone? | 1. Noise pollution 2. Dust pollution 3. Exploiting natural resource 4. Blasting scares wildlife 5. Scars environment 6. Loss of habitat |
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