Acids and Alkalis Flashcards
What is an acid?
An acid forms acidic solutions in water.
What is an alkali?
An alkali forms alkaline solutions in water.
What colours represent acid on the PH scale?
Yellow-Red
What colours represent Alkalis on the PH scale?
Blue-purple
What colour does red litmus paper turn when a solutions acidic?
It stays red
What colour does red litmus paper turn when a solutions nuetral?
It stays red
What colour does red litmus paper turn when a solutions alkaline?
It turns blue
What colour does blue litmus paper turn when a solutions acidic?
It turns red
What colour does blue litmus paper turn when a solutions nuetral?
It stays blue
What colour does blue litmus paper turn when a solutions alkaline?
It stays blue
What is a base?
Any substance that reacts with an acid to form a salt and water only.
What is a base that’s soluble in water called?
An alkaline
Give an example for a base soluble in water and a base not soluble in water.
- Copper oxide is a base, but it is not an alkali because it is insoluble in water
- Sodium hydroxide is a base, and it dissolves in water so it is also an alkali
What is a neutralisation reaction?
A reaction between an acid and a base.
What happens in an acid-alkali neutralisation reaction?
hydrogen ions from the acid react with hydroxide ions from the alkali.
What’s the products of when an acid reacts with a metal?
Acid + metal → salt + hydrogen
How do you test for hydrogen gas?
The Squeaky Pop Test
You can safely test for small quantities of hydrogen gas by holding a burning splint near the top of the test tube. The positive result is a squeaky pop sound as the hydrogen reacts with oxygen in the air in a small explosion.
What is a redox (oxidation-reduction) reaction?
A reaction in which both oxidation and reduction occur.
Give an example of a redox reaction.
the reaction of magnesium with hydrochloric acid:
2H+(aq) + Mg(s) → Mg2+(aq) + H2(g)
This ionic equation can be split into two half equations:
Mg(s) → Mg2+(aq) + 2e- (oxidation)
2H+(aq) + 2e- → H2(g) (reduction)
Notice that:
magnesium atoms lose electrons - they are oxidised
hydrogen ions gain electrons - they are reduced
How is a salt named?
The name of a salt has two parts:
- The first part comes from the base, alkali or metal carbonate.
- The second part comes from the acids.
What salt does hydrochloric acid produce?
Chloride salts
What salt does nitric acid produce?
Nitrate salts
What salt does sulfuric acid produce?
Sulfate salts
