(a) What is the structure of:
(i) graphite:
(ii) diamond
(ii) Explain briefly why diamond is hard and a non-conductor of electricity while graphite is soft and an electrical conductor,
(b)i. State what is achieved at each of the following stages in the purification of town water supply:
- aeration;
- screening
- sedimentation.
(ii) Name two substances responsible for hardness in water.
(iii) State two methods for the removal of hardness in water.
(iv) Give one disadvantage of hard water
(c)i). Describe briefly the extraction of tin from its ore.
(ii) Write a balanced chemical equation for the reaction.
(iii) Write an equation for the reaction of tin with:
- oxygen;
- chlorine.
(a)
(i) Graphite is made up of layers of carbon atoms arranged in a hexagonal pattern. Each carbon atom is bonded covalently to three neighboring carbon atoms, forming a flat layer. These layers are stacked on top of each other, held together by weak van der Waals forces.
(ii) Diamond, on the other hand, is made up of carbon atoms arranged in a three-dimensional crystal lattice structure, with each carbon atom bonded covalently to four other carbon atoms. The strong covalent bonds between the carbon atoms give diamond its hardness and high melting point.
Diamond is hard because of its tightly packed, three-dimensional crystal structure, which makes it difficult for other materials to scratch or break the bonds between the carbon atoms. Graphite, in comparison, is soft because its layers are held together by weak van der Waals forces, which allows the layers to slide easily over one another.
Diamond is a non-conductor of electricity because it is an insulator, meaning that electrons cannot flow freely through its crystal structure. Graphite, on the other hand, is a conductor of electricity because its layers can act as a pathway for electrons to flow through.
(b) (i) In the purification of town water supply:
- Aeration involves adding air to the water, which helps to remove dissolved gases and improve the taste and odor of the water.
- Screening involves removing large particles, such as debris or leaves, from the water.
- Sedimentation involves allowing the water to stand in a large tank, allowing suspended particles to settle to the bottom.
(ii) Calcium and magnesium are two substances responsible for hardness in water.
(iii) Two methods for the removal of hardness in water are ion exchange and reverse osmosis.
(iv) One disadvantage of hard water is that it can cause scale buildup in pipes and appliances, reducing their efficiency and lifespan.
(c) (i) Tin is extracted from its ore, typically cassiterite (SnO2), by heating the ore in a furnace with carbon to form tin metal and carbon dioxide gas.
(ii) The balanced chemical equation for the reaction is:
2SnO2 + 5C ? 2Sn + 4CO2
(iii) The reaction of tin with:
- Oxygen: Tin reacts with oxygen to form tin dioxide (SnO2).
- Chlorine: Tin reacts with chlorine to form tin(IV) chloride (SnCl4).
(a)
(i) Graphite is made up of layers of carbon atoms arranged in a hexagonal pattern. Each carbon atom is bonded covalently to three neighboring carbon atoms, forming a flat layer. These layers are stacked on top of each other, held together by weak van der Waals forces.
(ii) Diamond, on the other hand, is made up of carbon atoms arranged in a three-dimensional crystal lattice structure, with each carbon atom bonded covalently to four other carbon atoms. The strong covalent bonds between the carbon atoms give diamond its hardness and high melting point.
Diamond is hard because of its tightly packed, three-dimensional crystal structure, which makes it difficult for other materials to scratch or break the bonds between the carbon atoms. Graphite, in comparison, is soft because its layers are held together by weak van der Waals forces, which allows the layers to slide easily over one another.
Diamond is a non-conductor of electricity because it is an insulator, meaning that electrons cannot flow freely through its crystal structure. Graphite, on the other hand, is a conductor of electricity because its layers can act as a pathway for electrons to flow through.
(b) (i) In the purification of town water supply:
- Aeration involves adding air to the water, which helps to remove dissolved gases and improve the taste and odor of the water.
- Screening involves removing large particles, such as debris or leaves, from the water.
- Sedimentation involves allowing the water to stand in a large tank, allowing suspended particles to settle to the bottom.
(ii) Calcium and magnesium are two substances responsible for hardness in water.
(iii) Two methods for the removal of hardness in water are ion exchange and reverse osmosis.
(iv) One disadvantage of hard water is that it can cause scale buildup in pipes and appliances, reducing their efficiency and lifespan.
(c) (i) Tin is extracted from its ore, typically cassiterite (SnO2), by heating the ore in a furnace with carbon to form tin metal and carbon dioxide gas.
(ii) The balanced chemical equation for the reaction is:
2SnO2 + 5C ? 2Sn + 4CO2
(iii) The reaction of tin with:
- Oxygen: Tin reacts with oxygen to form tin dioxide (SnO2).
- Chlorine: Tin reacts with chlorine to form tin(IV) chloride (SnCl4).
