Daily Practice · GCSE Science

Daily Practice - GCSE Science

24th February 1999

5 questions · GCSE · 584 questions in this band

1
Energy Changes
Explain, in terms of bonds, why breaking bonds is an endothermic process.
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 increasing the surface area of a solid reactant increases the rate of a reaction.

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