Acids and Bases Flashcards
how much does the pH scale go up to
0 to 14
what does the pH scale measure
how acidic or alkaline a solution is
what if the pH of a solution is low
more acidic
what if the pH of a solution is high
more alkaline
what is the pH of a neutral substance
pH 7 (e.g. pure water)
what is an indicator
a dye that changes colour depending on whether its above or below a certain pH.
what are wide range indicators
mixture of dyes that means they gradually change colour over a broad range of pH. They are useful for estimating the pH of a solution.
How can you measure pH electronically
a pH probe attached to a pH meter. The probe is placed in the solution you are measuring and the pH is given on a digital display as a numerical values
what is an acid
a substance that forms aqueous solutions with a pH less than 7
acids form H+ ions in water
what is a base
a substance with a pH greater than 7
what is an alkali
a base that dissolves in water to form solution with a pH greater than 7.
Alkalis form OH- ions in water
what is the reaction between acids and bases called
neutralisation
reaction of acids and bases:
acid + base – salt + water
how is neutralisation between acids and alkalis seen as
in terms of H+ and OH- ions like this:
H+(aqueous) + OH-(aqueous) – H2O(liquid)
what happens when an acid neutralises a base (or vice versa)
the products are neutral, i.e. they have a pH of 7.
an indicator can be used to show that a neutralisation reaction is over.
