Paper 1 - Chemical Changes Flashcards
Which type of indicator is used to test for pH?
Universal indicators are used for testing for pH
If a solution has a pH below 7, what is it?
A pH below 7 - Acid
If a solution has a pH above 7, what is it?
A pH above 7 - Akali
If a solution has a pH of 7, then it is n_____
neutral
What type of ions do acids form in water?
Acids form H+ ions in water
What type of ions does alkali form in water?
Alkalis form OH- ions in water
What is a base?
A base is a substance with a pH greater than 7
Acid + base > __ + __ ? What type of reaction is this?
Acid + base > salt + water = neutralisation reaction
What is the symbol equation for neutralisation?
The symbol equation for neutralisation is H+ (aq) + OH- (aq) > H20 (l)
What are titrations for?
Titration tests for concentration in a solution and for knowing the exact amount of acid needed to neutralise a solution
What is the process of finding the concentration of alkali with titration? (7 steps)
- Add a set volume of alkali to a conical flask using a pipette and pipette filler.
- add a universal indicator
- use funnel to fill a burette with the acid of known concentration (below eye level)
- record the initial volume of acid
- use burette to add a little acid at a time to the alkali, swirling the flask at the same time
- indicator will change once it has been neutralised
- record the final volume of acid and calculate the increase from the initial reading
Why should you repeat a titration?
You should repeat a titration multiple times because they may be a random and systematic error that may have affected the results
What is a strong acid?
A strong acid is an acid that completely ionises (dissociates) in water to form hydrogen ions
What is a weak acid?
A weak acid is an acid that partially ionises (dissociates) in water to form hydrogen ions
What are some examples of strong acids?
Some examples of strong acids include hydrochloric acid, sulfuric acid, nitric acid
