Acids and Alkalis Flashcards
What is the pH scale a measure of?
How acidic or alkaline a solution is
What is the range of the pH scale? What does that mean?
pH 0 - strongest acid
pH 14 - Strongest alkali
What is the pH of a neutral substance? Give an example
pH 7 - pure water
What do you use to test the pH of a solution? How does it work?
An indicator - the dye in an indicator changes colour depending on whether it’s above or below a certain pH
Describe Universal indicator?
A combination of dyes which gives the colours of the pH scale.
Describe the colours of the pH scale
Dark red = pH 0 Orange = pH 3 Green = pH 7 Bluey purple = pH 10 Bright purple = pH 14
What is an acid?
A substance with a pH less than 7. Acids form H+ ions in water
What is an base?
Substance with a pH greater than 7
What is an alkali?
A base that dissolves in water. Alkalis form OH- ions in water
Describe how ions make something acidic/alkaline
H+ = acidic
OH - = alkaline
What is the name for a reactions between acids and bases? Write the general word equation
Neutralisation
Acid + Base -> Salt + Water
What is the ion equation of a neutralisation reaction?
H+ (aq) + OH- (aq) -> H₂O (l)
What can be used to determine whether a neutralisation is over?
An indicator
What are the state symbols? and what do they mean?
(s) - solid
(l) - liquid
(g) - gas
(aq) - aqueous, dissolved in water