Hydrocarbon is a simple organic compound that contains carbon and a. hydrogen only. If the carbon...

 

Transcribed Image Text:

Hydrocarbon is a simple organic compound that contains carbon and a. hydrogen only. If the carbon atoms are linked in chains and single bonds, the compounds are called aliphatic alkanes with general formula, CaH2n+2. Aliphatic alkanes in the range ofn = 1 to n = 4 are gases, highly flammable, and colourless at atmospheric pressure (1 atm) and room temperature (25°C). A large volume of air is required for complete combustion of alkanes gases under standard conditions. To calculate the standard enthalpy of combustion, AH comb., a particularly important process used for tabulating thermochemical data is the standard enthalpy of formation, AH. TABLE Q2 shows the thermodynamic quantities for some substances at 25°C. TABLE Q2 Substance Physical state AH" (kJ/mol) AS (J/mol.K) Water Liquid -285.83 69.91 Ethane Gas -84.68 229.50 Butane Gas -124.73 310.00 Oxyg Gas 205.00 Graphite Solid 5.69 Propane Gas -103.85 269.9 Methane Gas -74.80 186.3 Hydrogen Gas 130.58 Carbon dioxide Gas -393.50 213.60 i. Using Hess's law, deduce the thermochemical reactions that take place in the combustion of your selected hydrocarbon. Calculate AH"comb. and describe the process of combustion of hydrocarbon. ii. Calculate the standard entropy change of the reaction and explain the spontaneity of the reaction with the decrease of temperature. [5 marks) b. The purpose of electroplating is to prevent corrosion. Electroplating is a process of coating an inferior object with a superior metal through electrolysis. Electroplating process requires expensive and efficient treatment of waste. Eventually, due to contamination, the quality of the coated objects drops. "Spoon is an inexpensive metal, but when coated with a superior metal they become valuable" By using your knowledge in electrolysis, design an experiment to discuss the statement. Provide your arguments clearly on how to improve the quality of the coated metal formed by electroplating. [10 marks] Hydrocarbon is a simple organic compound that contains carbon and a. hydrogen only. If the carbon atoms are linked in chains and single bonds, the compounds are called aliphatic alkanes with general formula, CaH2n+2. Aliphatic alkanes in the range ofn = 1 to n = 4 are gases, highly flammable, and colourless at atmospheric pressure (1 atm) and room temperature (25°C). A large volume of air is required for complete combustion of alkanes gases under standard conditions. To calculate the standard enthalpy of combustion, AH comb., a particularly important process used for tabulating thermochemical data is the standard enthalpy of formation, AH. TABLE Q2 shows the thermodynamic quantities for some substances at 25°C. TABLE Q2 Substance Physical state AH" (kJ/mol) AS (J/mol.K) Water Liquid -285.83 69.91 Ethane Gas -84.68 229.50 Butane Gas -124.73 310.00 Oxyg Gas 205.00 Graphite Solid 5.69 Propane Gas -103.85 269.9 Methane Gas -74.80 186.3 Hydrogen Gas 130.58 Carbon dioxide Gas -393.50 213.60 i. Using Hess's law, deduce the thermochemical reactions that take place in the combustion of your selected hydrocarbon. Calculate AH"comb. and describe the process of combustion of hydrocarbon. ii. Calculate the standard entropy change of the reaction and explain the spontaneity of the reaction with the decrease of temperature. [5 marks) b. The purpose of electroplating is to prevent corrosion. Electroplating is a process of coating an inferior object with a superior metal through electrolysis. Electroplating process requires expensive and efficient treatment of waste. Eventually, due to contamination, the quality of the coated objects drops. "Spoon is an inexpensive metal, but when coated with a superior metal they become valuable" By using your knowledge in electrolysis, design an experiment to discuss the statement. Provide your arguments clearly on how to improve the quality of the coated metal formed by electroplating. [10 marks]