Acids 🍊 Flashcards
Which ions make aqueous solutions acidic?
H+ (Hydrogen ions)
Which ions makes aqueous solutions alkaline?
OH- (Hydroxide ions)
What is the pH scale?
The pH scale ranges from pH 0 to pH 14 and measures the acidity or alkalinity of a solution.
What can be used to measure pH?
Universal indicator
pH probe
What colour is phenolphthalein in acid and alkali?
Acid - Colourless
Alkali - Pink
What colour is methyl orange in an acid and an alkali?
Acid - Red
Alkali - Yellow
What colour is blue litmus paper in an acid and an alkali?
Acid - turns red
Alkali - stays blue
What colour is red litmus paper in an acid and an alkali?
Acid - Stays red
Alkali - Turns blue
Suggest a problem with using universal indicator to test the pH of a solution.
The colour of the solution is matched to the pH colour chart. This is quite subjective as people may disagree with which colour the solution matches.
It doesn’t provide an exact pH value.
If pH decreases by one unit, what happens to the concentration of hydrogen ions?
The hydrogen ion concentration increases by a factor of 10.
What is a neutralisation reaction? During an acid-alkali neutralisation reaction, what happens?
A neutralisation reaction is a reaction between an acid and a base.
In an acid-alkali neutralisation reaction, H+ ions from the acid react with OH- ions from the alkali to form water.
What does concentrated acid mean?
The acid has a high proportion of acid (H+) molecules.
What does dilute acid mean?
The acid has a low proportion of acid (H+) molecules in it
What does strong acid mean?
Strong acids has completely ionised/ disassociated in water (they separate into ions)
What does weak acid mean?
Weak acids have only partially ionised/disassociated in water (some separate into ions, some stay as acids)
