Daily Practice - GCSE Science
1st November 1998
- 1Electrolysis
Concentrated sodium chloride solution (brine) is electrolysed using inert electrodes. State the products formed at the cathode and at the anode.
- 2Energy Changes
A reaction profile shows the reactants at 150 kJ and the peak (activation energy point) at 195 kJ. Calculate the activation energy.
- 3Exothermic 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.
- 4Bond 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.
- 5Rate 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).
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