Energy changes in reactions

What is meant by an exothermic reaction?

• An exciting reaction

• A reaction that takes in energy

• A reaction that gives out energy

• A reaction from outer space

What is meant by an endothermic reaction?

• A really cold reaction

• A reaction that takes in energy

• A reaction that gives out energy

• The end of a reaction

Which of these are exothermic reactions?

• Combustion

• Neutralisation

• Dissolving

• Respiration

Which of these are endothermic reactions?

• Displacement reactions

• Dissolving

• Respiration

• Photosynthesis

Which of these equations would you use to work out an energy change?

• n = c x v

• E = mc²

• Q = mcΔT

• n = m/Mr

Which of these equations would you use to work out the ΔH?

• ΔH = QmcΔT

• ΔH = ma

• ΔH = Qn

• ΔH = -Q/n

200 cm³ of 0.1 mol dm^-3 sodium hydroxide was mixed with 200 cm³ of 0.1 mol dm^-3 nitric acid. The temperature increased from 20 to 32°C. What was the energy change?

• Q = 200 x 4.2 x 32 = 26880 J

• Q = 400 x 4.2 x 32 = 53760 J

• Q = 200 x 4.2 x 12 = 10080 J

• Q = 400 x 4.2 x 12 = 20160 J

In an experiment to measure the energy change for a combustion reaction, which of the following cause the answer to be inaccurate?

• Heat loss to the surroundings

• Heat gain from the surroundings

• Evaporation of the water

• Incomplete combustion

Which of the following is true about the reaction shown in this diagram:

• It's exothermic and has a positive ΔH value

• It's exothermic and has a negative ΔH value

• It's endothermic and has a positive ΔH value

• It's endothermic and has a negative ΔH value

Explain how catalysts work:

• They give the reactants more energy so the reaction speeds up

• They push the reactants together so the reaction speeds up

• They provide an alternative pathway with a lower activation energy

• They produce heat which speeds up the reaction