C2.6 Acids, bases and salts Flashcards
What does the pH scale measure?
how acidic or alkaline a solution is
What are the 3 ways soluble salts can be made?
reacting acid with:
- metals
- insoluble bases
- alkalis
Describe how a soluble salt can be made by reacting acid with metal
Add metal to acid (metal needs to be more reactive than hydrogen)
metal will dissolve in acid as it reacts
filter out excess metal that has not dissolved to get salt solution
crystallisation- evaporate som of the water with a bunsen burner then leave to evaporate naturally to get cure, solid crystals of the salt.
What is the word equation for reacting a metal with acid?
acid + metal —– salt + hydrogen
What are the 4 state symbols and what do they stand for?
(s) solid
(l) liquid
(g) gas
(aq) aqueous - dissolved in water
In a reaction, the more reactive the metal…
the faster the rate of reaction
Why does copper not react with acids?
as it is less reactive than hydrogen
What is the test for hydrogen?
the burning split test- gives a squeaky pop
What type of salt will hydrochloric acid produce?
a chloride
What type of salt will sulfuric acid produce?
a sulfate
what type of salt does nitric acid produce?
a nitrate
What is an insoluble base?
a metal oxide or metal hydroxides
Describe the reaction with an insoluble base (metal oxide or metal hydroxide) and acid
Add insoluble base to acid. It will dissolve in the acid as it reacts.
You will know when all the acid has been neutralised because the excess solid will just sink to the bottom of the flask
excess solid filtered off to get salt solution
crystallisation- evaporate some of the water then leave the rest to evaporate slowly to get pure, solid crystals of salt
What is the word equation for reacting an insoluble base with a metal?
acid + insoluble base ——- salt + water
Describe how alkalis can be used to make salts?
Add alkali to an acid. Use an indicator to show when neutralisation has occurred
repeat using exact same volume of acid and alkali so the salt is not contaminated with indicator
crystallisation
What is the word equation of reacting an acid with an alkali?
Acid + Alkali = Salt + Base
Describe crystallisation
used to produce solid salts
evaporate some of water with a bunsen burner to make the solution more concentrated
leave the rest to evaporate slowly
what is a soluble salt?
a salt dissolved in water
What is an insoluble salt?
A salt which does not dissolve in water
What kind of reaction do you do if the salt you want to make is insoluble?
precipitation reaction
Describe how insoluble salts can be made
a precipitation reaction
by mixing appropriate solutions of ions so that a precipitate is formed.
filter salt from solution
Describe how you would make lead chloride
need a solution that contains lead ions and chloride ions.
Therefore, could mix lead nitrate solution with sodium chloride solution
Give an example of when precipitation reactions are used
used to remove unwanted ions from solutions
eg in treating water for drinking or in treating effluent
what are bases?
metal oxide and hydroxides
