Question 1: Chemical energy is stored within the bonds of chemical substances. When these bonds are broken during a chemical reaction, energy is either released or absorbed. This form of energy storage is crucial in many everyday applications, including fuels and batteries.

Answer: Chemical energy is stored in the bonds of chemical substances and is released or absorbed during reactions.

Question 1: Define chemical energy.

Answer: Energy stored in the bonds of chemical substances.

Question 2: Explain how chemical energy is released during a combustion reaction.

Answer: During combustion, chemical bonds in the fuel are broken and new bonds form in the products, releasing stored chemical energy as heat and light.

Question 1: A 2 kg of methane (CH4) undergoes complete combustion. Given that the combustion of 1 mol of methane releases 890 kJ of energy, calculate the total energy released. (Molar mass of CH4 = 16 g/mol)

Answer: Energy released = (mass / molar mass) * energy per mol = (2000 g / 16 g/mol) * 890 kJ = 125 mol * 890 kJ = 111,250 kJ.

Question 1: Describe a safe method for heating a chemical substance to measure its energy change, including safety precautions.

Answer: Use a heat-resistant container, perform the experiment in a well-ventilated area or under a fume hood, wear safety goggles and gloves, and avoid direct contact with hot substances.

Question 1: A chemical reaction releases 500 kJ of energy when 100 g of a substance reacts. What is the energy released per gram of the substance?

Answer: Energy per gram = 500 kJ / 100 g = 5 kJ/g.

Question 1: Describe how chemical energy is stored in batteries and explain the process by which energy is converted into electrical energy.

Answer: Batteries store chemical energy in the form of chemical compounds. When a battery is connected in a circuit, a chemical reaction occurs at the electrodes, causing a flow of electrons. This flow of electrons provides electrical energy that powers devices, converting chemical energy into electrical energy.

Question 1: Explain how chemical energy stores are utilised in the design of hybrid and electric vehicles.

Answer: Hybrid and electric vehicles use batteries to store chemical energy, which is converted into electrical energy to power electric motors, reducing reliance on fossil fuels and lowering emissions.