Daily Practice - GCSE Science
11th February 1998
- 1Concentration, Yield and Atom Economy
Give the formula for atom economy.
- 2Chemical Changes
A student reacts 2.4 g of magnesium with excess dilute hydrochloric acid: Mg + 2HCl -> MgCl2 + H2. Relative atomic mass of Mg = 24. Calculate the number of moles of hydrogen gas produced.
- 3Reactivity, Acids and Salts
Why is aluminium extracted by electrolysis rather than by reduction with carbon?
- 4Electrolysis
Concentrated sodium chloride solution (brine) is electrolysed using inert electrodes. State the products formed at the cathode and at the anode.
- 5Energy Changes
A reaction profile shows the reactants at 220 kJ and the products at 340 kJ. State whether the reaction is exothermic or endothermic.
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