Acids, Bases and Alkalis Flashcards
What colour is methyl orange in acidic conditions?
Red
What colour is methyl orange in neutral conditions?
Yellow
What colour is methyl orange in alkali conditions?
Yellow
What colour is phenolphthalein in acidic conditions?
Colourless
What colour is phenolphthalein in neutral conditions?
Colourless
What colour is phenolphthalein in alkali conditions?
Pink
What colour is red litmus paper in acidic conditions?
Red
What colour is red litmus paper in neutral conditions?
Red
What colour is red litmus paper in alkali conditions?
Blue
What colour is blue litmus paper in acidic conditions?
Red
What colour is blue litmus paper in neutral conditions?
Blue
What colour is blue litmus paper in alkali conditions?
Blue
Define an acid:
H⁺ donor.
Define a base:
H⁺ acceptor.
Define an alkali:
OH- donor
Name 4 important alkalis:
-Sodium hydroxide
-Potassium hydroxide
-Ammonium hydroxide
-(All soluble metal hydroxides)
Name 3 important bases:
-Ammonia
-(All metal oxides)
-(All metal hydroxides)
What is a polyatomic ion?
An ion that contains more than 1 atom.
What contains polyatomic ions?
Some of the important acids, bases and alkalis
What is the name and formula of the polyatomic ion released by nitric acid?
Nitrate
NO3-
What is the name and formula of the polyatomic ion released by all alkalis (apart from ammonium hydroxide)?
Hydroxide
OH-
What is the name and formula of the polyatomic ion released by ammonium hydroxide?
Ammonium
NH4+
Metal + Acid ->
Metal + Acid -> Salt + Hydrogen
Acid + Base ->
Acid + Base -> Salt + Water
Metal oxide + acid ->
Metal oxide + acid -> Salt + Water
Metal hydroxide + Acid ->
Metal hydroxide + Acid -> Salt + Water
What is the one important observation in an acid + base reaction?
The base disappears, because it is used up in the reaction.
What happens if the salt formed in an acid + base reaction is soluble?
It dissolves in the water to form a salt solution.
What reaction can we use to make salt crystals?
An acid + base reaction.
What 4 steps are needed to make zinc sulphate crystals?
1) Add excess base (ZnO) to hot acid (H2SO4). This makes the salt solution ZnSO4.
2) Filter out the excess base. The salt solution (ZnSO4) is the filtrate and collected in an evaporating basin.
3) Heat the salt solution until crystals begin to form around the edges.
4) Leave the salt solution to crystallise.
Why do we add excess base to the acid when making salt crystals?
To ensure all the acid is used up.
Why does the acid have to be hot in the first step of making salt crystals?
To make the salt solution quickly.
Why do we heat the salt solution in step 3 of making salt crystals?
To saturate the solution so that crystals form most efficiently.
Why do we have we have to leave the saturated salt solution in step 4 of making salt crystals?
So evaporation of water can allow crystals to form.
Acid + Carbonate ->
Acid + Carbonate -> Salt + Water + Carbon Dioxide
What are the two important observation in an acid + carbonate reaction?
-The carbonate disappears because it is used up in the reaction
-Fizzing/effervescence as a gas (carbon dioxide) is produced.
What kind of metals don’t react with dilute acids?
Metals below hydrogen in the reactivity series.
What kind of metals react with dilute acids to produce hydrogen gas?
Metals above hydrogen in the reactivity series.
Metal oxides are acids, alkalis or bases?
Bases.
What 3 things can bases be?
-Metal oxide
-Metal hydroxide
-Ammonia
What do bases do regarding acids?
Bases are substances that neutralise acids by combining with the hydrogen ions in them to produce water.
What is the colour change in the reaction between copper (II) carbonate and dilute acids?
Green copper (II) carbonate to blue or blue-green copper (II) sulfate, copper (II) nitrate or copper (II) chloride.
