Chemistry - End of Year Exams 10

Combustion, Enthalpy, Exothermic vs Endothermic, etc

Complete Combustion

When each of the reactants get used up fully to create the end product

Incomplete Combustion

When the fuel doesn’t react fully with the oxygen and thus produces soot or carbon monoxide (CO)

Hydrocarbons

chains of hydrogen + carbon

Flash Point

the lowest temperature at which there is enough gas for the fuel to ignite

Activation Energy

amount of energy needed to start a reaction

Enthalpy Change

Amount of energy absorbed or released during a chemical reaction

Endothermic reaction

take in energy and the temperature of the surroundings decreases (positive enthalpy change)

Exothermic reaction

transfer energy to the surroundings and the temperature of the surroundings increases (negative enthalpy change)

Catalyst

Decreases amount of energy needed to start a chemical reaction (acts as “jumpstarter”)

Bond Enthalpy Equation

sum of bonds broken - sum of bonds formed

Voltaic Cells

Devices that use a chemical reaction between two cells to create energy

Complete Combustion of Octane

2C(8)H(18) + 25O(2) —> 16CO(2) + 18H(2)O

Word equation of Combustion of Octane

Octane + Oxygen —> Carbon Dioxide + Water

Lithium Ion Batteries

Lithium-ion batteries operate by transferring lithium ions between the positive and negative electrodes during charging and discharging, enabling the storage and release of electrical energy.