Acids and Alkalis Flashcards
On a hazard card, what would the picture look like to show that something is poisonous?
A skull and cross bones
On a hazard card, what would the picture look like to show that something is corrosive?
A hand with a burn mark on it.
Kitchen cleaners that are able to remove limescale and make surfaces shiny contain an acid that is usually around pH 2, is this a strong or weak acid?
Strongly acidic - Red on the pH scale
What is the colour of a solution that is pH 7?
Green
bicarbonate of soda is an alkaline, what colour would it turn universal indicator?
blue
What gas is produced when bicarbonate is added to acid?
carbon dioxide
How can you test for carbon dioxide?
Bubble through limewater, it will turn milky/cloudy if carbon dioxide is present.
What is the chemical name for limestone?
calcium carbonate
What acid would you use to make zinc sulphate?
sulphuric acid
acid + alkali ->
salt + water
acid + metal oxide ->
salt + water
acid + metal ->
salt + hydrogen
acid + metal carbonate ->
salt + water + carbondioxide
How would you know a gas had been given off in a reaction?
Bubbles are formed
How do you test for hydrogen
lighted splint goes pop
How can you obtain crystals from a salt solution?
evaporate the water
Hydrochloric acid will make what type of salt?
chloride
sodium hydroxide + hydrochloric acid ->
sodium chloride + water
When making copper chloride, you add lots of copper oxide to hydrochloric acid. How do you remove the unreacted copper oxide?
filter it using filter paper and a funnel.
When making copper chloride, why do you add more copper oxide that you need?
To make sure all the hydrochloric acid has been neutralised.
Some metals do not react with acid, can you name one?
copper - unreactive in acid
What is displacement?
a more reactive metal will displace (take the place of) a less reactive metal in a salt solution.
iron + copper sulphate ->
iron sulphate + copper (iron is more reactive, so displaces copper)
copper + zinc sulphate ->
no change. (zinc is more reactive that copper so copper is unable to displace it from its salt)
name metals more reactive than iron
zinc, magnesium, calcium are a few.
How do you carry out a titration?
A pipette is used to measure accurately a volume of acid - for example, 10cm3. This is emptied into a conical flask.
A few drops of an indicator may be added to the conical flask. This will show a change of colour when the titration is complete.
The burette is filled with an alkali.
The solution from the burette is run into the conical flask. The solution is added one drop at a time, with swirling to mix the solutions as the end-point is approached. Eventually, a colour change shows that the correct amount has been added to react completely with the acid. It is now neutral.
Measure the volume of alkali that was needed.
