Combustion Experiments in Year 8

Year 8 SISKY students performed a lab investigation on Friday 16 February to compare the energy released in 4 different fuels. Alcohols have a predictable pattern formula of carbon, hydrogen and oxygen atoms; they follow the pattern CnH2n+1OH. Students determined the formula of four alcohols using the number of carbons to determine the full chemical formula. Methanol has 1 carbon atom, ethanol has 2, propanol has 3, and butanol has 4. Students then produced balanced chemical reactions for the combustion represented by the formulas of the reactants (the alcohols with oxygen) and products (water and carbon dioxide). Using the knowledge that breaking bonds requires energy, and forming bonds releases energy, students tried to predict which of the four alcohols would be the most exothermic when combusting. Using only 20 ml of water, students heated the room temperature water for 10 minutes using the different alcohols. Students will calculate the relationship between change in temperature of the water and change in mass of the fuels to determine which fuel released the most energy.

Year 8 students are considering real world problems of choosing the right fuel for specific tasks and are working to solve issues such as carbon dioxide emissions from the burning of hydrocarbons as well thinking about pollution from incomplete combustion.