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IGCSE Chemistry Complete
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IGCSE Chemistry Complete IGCSE Chemistry Complete IGCSE Chemistry Complete
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IGCSE Chemistry CompleteState the method used to obtain sand from a mixture of sand and water - ANS filtration
State the method used to obtain solid copper sulfate from aqueous copper sulfate - ANS crystallisation
State the method used to obtain red food dye from a mixture of food dyes - ANS paper chromatography
State the method used to obtain water from salt water - ANS simple distillation
Draw a diagram to show equipment used in simple distillation - ANS For what process is this equipment
used?
State the method used to obtain kerosene from a crude oil. - ANS fractional distillation
Draw the equipment used in fractional distillation in the lab - ANS For what process is this equipment
used?
Explain how fractional distillation is used to separate a mixture of different liquids - ANS The different
liquids have different boiling points
State the method used to extract the red dye from a sample of rose petals - ANS dissolving
Describe how pure salt can be obtained from rock salt - ANS 1) Grind rock salt into a fine powder. 2) Add
powder to hot water and stir to dissolve salt. 3) Filter mixture. Salt solution passes through the filter
paper leaving behind the sand. 4) Boil filtrate to evaporate some of the water. 5) Leave saturated
solution to cool so that crystals of salt form. 6) Filter cold mixture to separate the crystals from the
remaining solution.
,Ethanol is a flammable liquid. Suggest how it could be heated safely - ANS Use a water bath
Explain how a chromatogram shows that different dyes are different from each other - ANS Each dyes
has a different mixture
State the expression for calculating molar concentration - ANS Molar concentration = Amount (in
moles)/volume (in dm^³)
Which cation gives a crimson red flame colour? - ANS Li⁺
Which cation gives a orange flame colour? - ANS Na⁺
Which cation gives a lilac flame colour? - ANS K⁺
Which cation gives a brick red flame colour? - ANS Ca²⁺
Describe how you would carry out a flame test - ANS Put solid onto a wire. Put into a blue flame
How would you test for the ammonium ion? - ANS Add sodium hydroxide. If ammonium ions were
present, ammonia gas will form which will turn damp red litmus paper blue
Describe how you would test for Cu²⁺ ions - ANS Add sodium hydroxide and a blue precipitate will form
Give the formula of the blue precipitate formed when sodium hydroxide is added to a solution
containing Cu²⁺ - ANS Cu(OH)₂
,Describe how you would test for Fe²⁺ ions - ANS Add sodium hydroxide and a green precipitate will form
Write a word equation for the reaction between sodium hydroxide and iron(II) sulfate - ANS sodium
hydroxide + iron(II) sulfate -> iron (II) hydroxide + sodium sulfate
Describe how you would test for Fe³⁺ ions - ANS Add sodium hydroxide and a brown precipitate will
form
What 2 things are added to a solution to test for chloride ions? What is observed if they are present? -
ANS Add dilute nitric acid and silver nitrate. A white precipitate of silver chloride is formed.
Describe the test for bromide ions. - ANS Add dilute nitric acid and silver nitrate. A cream precipitate of
silver bromide is formed.
After adding nitric acid and silver nitrate to a solution containing iodide ions, what colour precipitate is
formed? - ANS A yellow precipitate (of silver iodide) is formed.
Why is hydrochloric acid added before barium chloride solution in testing for sulfate ions? - ANS To
remove carbonate ions
Describe how you would test for sulfate ions - ANS Add dilute HCl, followed by BaCl₂. A white precipitate
will form
Write an chemical equation for the reaction between barium chloride and lithium sulfate (Li₂SO₄).
Include state symbols. Also, what would you see? - ANS BaCl₂ (aq) + Li₂SO₄ (aq) -> BaSO₄ (s)+ 2LiCl (aq).
Observe a white precipitate of barium sulfate.
Describe how you would test for carbonate ions, CO₃²⁻ - ANS Add nitric acid and see if carbon dioxide
bubbles form
, Describe the test for ammonia gas - ANS Turns damp red litmus paper blue
State the expression for calculating % yield. (Triple science only!) - ANS % yield = (actual amount of
products/theoretical amount of products) x100
Describe the chemical test for water - ANS Add water to anhydrous copper(II) sulfate which will change
from white to blue if water is present
What is the symbol for a reversible reaction? - ANS
The addition of water to anhydrous copper sulfate can be used to test for the presence of water. The
reaction is reversible. What is the word equation? Describe the colour change. - ANS anhydrous copper
sulfate (white) + water <-> hydrated copper sulfate (blue)
Ammonia and hydrogen chloride react together in a reversible reaction to produce a white solid. What
are the word and symbol equations? - ANS ammonia + hydrogen chloride <-> ammonium chloride NH₃ +
HCl <-> NH₄Cl
State two features of a reaction that is in dynamic equilibrium - ANS 1) The rate of the forward reaction
is equal to the rate of the backward reaction. 2) There is no overall change in concentrations.
Predict what will happen to the equilibrium position in the following reaction when the pressure is
increased. Give a reason for your prediction: CH₄(g) + H₂O(g) <-> CO(g) + 3H₂(g) ΔH = +210 kJ mol⁻1 - ANS
Equilibrium will move to the left because there are fewer molecules on the left hand side
Predict what will happen to the equilibrium position in the following reaction when the temperature is
increased. Give a reason for your prediction: CH₄(g) + H₂O(g) <-> CO(g) + 3H₂(g) ΔH = +210 kJ mol⁻1 - ANS
Equilibrium will move to the right because the forward reaction is endothermic
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