Limestone and Building materials

Limestone is mainly made up of calcium carbonate and the formula for that is CaCO3, which when heated breaks down to form calcium oxide and carbon dioxide. (CaCO3 -(heat)-> CaO + CO2

Calcium oxide reacts with water to produce calcium hydroxide. Limestone and its products have many uses, including being used to make cement, mortar and concrete.

Calcium carbonate breaks down when heated strongly. This reaction is called thermal decomposition. Here are the equations for the thermal decomposition of calcium carbonate

Other metal carbonates decompose in the same way, including: sodium carbonate magnesium carbonate copper carbonate

Metals high up in the reactivity series (such as sodium, calcium and magnesium) have carbonates that need a lot of energy to decompose them. Indeed, not all the carbonates of group 1 metals decompose at the temperatures reached by a Bunsen burner.

Metals low down in the reactivity series, such as copper, have carbonates that are easily decomposed. This is why copper carbonate is often used at school to show thermal decomposition. It is easily decomposed and its colour change, from green copper carbonate to black copper oxide, is easy to see.

making calcium carbonate If calcium carbonate is heated strongly, it breaks down to form calcium oxide and carbon dioxide. Calcium oxide is yellow when hot, but white when cold. Here are the equations for this reaction:calcium carbonate  calcium oxide + carbon dioxideCaCO3 CaO + CO2This is a thermal decomposition reaction.making calcium hydroxideCalcium oxide reacts with water to form calcium hydroxide, which is an alkali. Here are the equations for this reaction:calcium oxide + water → calcium hydroxideCaO + H2O → Ca(OH)2A lot of heat is produced in the reaction, which may even cause the water to boil.

Uses Of LimestoneLimestone is a type of rock, mainly composed of calcium carbonate. Limestone is quarried (dug out of the ground) and used as a building material. It is also used in the manufacture of cement, mortar and concrete. Reactions with acids Carbonates react with acids to produce carbon dioxide, a salt and water. For example:calcium carbonate + hydrochloric acid → carbon dioxide + calcium chloride + waterCaCO3 + 2HCl → CO2 + CaCl2 + H2OSince limestone is mostly calcium carbonate, it is damaged by acid rain. Sodium carbonate, magnesium carbonate, zinc carbonate and copper carbonate also react with acids: they fizz when in contact with acids, and the carbon dioxide released can be detected using limewater. Calcium hydroxide When limestone is heated strongly, the calcium carbonate it contains decomposes to form calcium oxide. This reacts with water to form calcium hydroxide, which is an alkali. Calcium hydroxide is used to neutralise excess acidity, for example, in lakes and soils affected by acid rain. Cement, mortar and concrete Cement is made by heating powdered limestone with clay. Cement is an ingredient in mortar and concrete: mortar, used to join bricks together, is made by mixing cement with sand and water concrete is made by mixing cement with sand, water and aggregate (crushed rock) Advantages and disadvantages of various building materials Limestone, cement and mortar slowly react with carbon dioxide dissolved in rainwater and wear away. This damages walls made from limestone, and leaves gaps between bricks in buildings. These gaps must be filled in or ‘pointed’. Pollution from burning fossil fuels makes the rain more acidic than it should be, and this acid rain makes these problems worse.Concrete is easily formed into different shapes before it sets hard. It is strong when squashed, but weak when bent or stretched. However, concrete can be made much stronger by reinforcing it with steel. Some people think that concrete buildings and bridges are unattractive. Quarrying You need to be able to evaluate some of the effects of the limestone industry. The main advantages and disadvantages of the limestone industry AdvantagesDisadvantagesLimestone is a valuable natural resource, used to make things such as glass and concrete.Limestone quarries are visible from long distances and may permanently disfigure the local environment.Limestone quarrying provides employment opportunities that support the local economy in towns around the quarry.Quarrying is a heavy industry that creates noise and heavy traffic, which damages people's quality of life.

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