Chemical reactions Flashcards
(3) Write the balanced equation for water decomposing to form hydrogen and
oxygen.
2H2O → 2H2 + O2 • reactant formula (1) • product formulae (1) • balancing correct formulae (1)
(2) Describe the test to show that a gas is hydrogen.
lighted splint
gas burns( 1)
• with (squeaky) pop (if air
present) (1)
(2) Describe the test to show that a gas is oxygen.
glowing splint (1) • relights (1)
(1) Seawater can also be decomposed using electrolysis.
Seawater is sodium chloride solution.
When this is decomposed one product is a toxic gas.
The toxic gas produced is
chlorine
(1) Give a safety precaution that should be taken when collecting this toxic gas.
use a fume cupboard/open all the
windows /(good) ventilation/wear a
gas mask
(1) When dilute hydrochloric acid reacts with copper oxide one of the products is
copper chloride
(2) Explain what is meant by electrolysis.
decomposition /break down of {compound / substance / electrolyte}(1) • using electricity / electrical energy / d.c supply (1)
(3) Chlorine gas reacts with sodium hydroxide solution to form sodium chlorate(I), NaOCl, sodium chloride and water
Write the balanced equation for this reaction
reactant formulae (1)
• product formulae (1)
• balancing correct formulae
(1)
(1) Sodium chloride solution can be prepared by reacting sodium hydroxide solution
with an acid.
Give the name of the acid that must be used.
hydrochloric (acid)
(1) Which row of the table correctly identifies chalk, marble and limestone as
sedimentary or metamorphic rocks?
sedimentary / metamorphic /
sedimentary
(2) Suggest how you could show that, when calcium carbonate is heated, a
reaction takes place.
{find mass of / weigh} solid before heating (1) • (heat in a suitable container) and {find mass / weigh} again (when cool) (1)
(2) Describe what you would observe when water is added, one drop at a time, to
cold calcium oxide
fizzing / hissing (1) • steam (1) • swells (1) • solid crumbles (to a powder) (1) • becomes hot (1)
(2) Write the balanced equation for the reaction of calcium hydroxide with
carbon dioxide
Ca(OH)2 + CO2 → CaCO3 + H2O
(1) State the common name for calcium hydroxide solution.
limewater
(2) Explain why calcium carbonate removes acidic gases from emissions in power
station chimneys.
(calcium carbonate) reacts with {acidic gases / sulphur dioxide} (1) • (because) calcium carbonate is a base (1) • to form a salt / calcium sulfate (1) • neutralisation (reaction) (1)