Daily Practice

GCSE Science

11th November 1981

5 questions · GCSE · 584 questions in this band

1
Energy Changes
A reaction profile shows the reactants at 150 kJ and the peak (activation energy point) at 195 kJ. Calculate the activation energy.
2
Exothermic and Endothermic Reactions
A student reacts excess zinc powder with 25 cm3 of copper sulfate solution in a polystyrene cup. The starting temperature is 21.0 degrees C and the maximum temperature reached is 58.5 degrees C. Calculate the temperature change.
3
Bond Energies, Cells and Fuel Cells
Hydrogen reacts with chlorine to form hydrogen chloride: H2 + Cl2 -> 2HCl. Use the bond energies given to calculate the overall energy change for this reaction. Bond energies: H-H = 436 kJ/mol, Cl-Cl = 243 kJ/mol, H-Cl = 432 kJ/mol.
4
Rate and Extent of Chemical Change
State what is shown on a rate graph when the line for the volume of gas produced becomes horizontal (flat).
5
Rates of Reaction
Explain why using a light sensor and data logger is more reliable than timing by eye in the disappearing cross practical.

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