Question 1: Define a giant covalent structure and give two examples.

Answer: A giant covalent structure is a large network of atoms bonded together by covalent bonds, forming a continuous three-dimensional structure. Examples include diamond and silicon dioxide.

Question 2: Explain why diamond is extremely hard and has a high melting point.

Answer: Diamond has a strong covalent network where each carbon atom is bonded to four others in a rigid structure, making it very hard and requiring a lot of energy to break the bonds, resulting in a high melting point.

Question 1: Calculate the energy required to convert 2 grams of graphite (C) into gaseous carbon atoms, given that the bond dissociation energy for carbon-carbon bonds in graphite is approximately 348 kJ/mol. Use the molar mass of carbon as 12 g/mol.

Answer: 138 kJ

Question 2: If a diamond contains approximately 3.5 x 10^23 carbon atoms, how many moles of carbon are in one diamond? Show your calculation.

Answer: Approximately 58.3 moles

Question 1: Describe a safe procedure to test the hardness of a diamond in a laboratory setting.

Answer: Use a standardized hardness test, such as scratching the diamond with a material of known hardness, while wearing safety goggles and gloves to protect against any accidental breakage or sharp fragments.

Question 2: Identify two variables that could affect the outcome of an experiment testing the melting point of silicon dioxide, and state how to control them.

Answer: Variables include the purity of silicon dioxide and the heating rate. To control them, use high-purity samples and heat at a consistent, slow rate to ensure accurate melting point measurement.

Question 1: A sample of silicon dioxide has a melting point of approximately 1700°C. Explain how its giant covalent structure contributes to this high melting point.

Answer: The extensive covalent bonds throughout the silicon dioxide crystal require a large amount of energy to break, resulting in a very high melting point.

Question 2: In what ways does the structure of diamond make it suitable for use in cutting tools?

Answer: Diamond's rigid three-dimensional covalent network makes it extremely hard and durable, allowing it to cut, grind, and drill other materials effectively. Its high thermal conductivity also helps dissipate heat generated during cutting.

Question 1: Explain why diamond is used in industrial cutting tools instead of graphite.

Answer: Diamond is much harder and more durable than graphite due to its covalent network structure, making it more suitable for cutting tools.

Question 2: Discuss a technological advancement that utilizes the properties of giant covalent structures.

Answer: The development of synthetic diamonds for high-precision cutting and scientific instruments utilizes the extreme hardness and thermal conductivity of giant covalent structures, improving manufacturing and technological capabilities.