Bases and alkalis

Question 1

What is a base?

Answer 1

Any substance that reacts with an acid to form a salt and water only. They are metal oxides and hydroxides.
In general
Base + acid -> salt + water

Question 2

When does a salt form?

Answer 2

When hydrogen ions in an acid are replaced by metal or ammonium ions.

Question 3

What do reactive metals produce when reacting with acids?

Answer 3

A salt and hydrogen

Question 4

How can you test for hydrogen?

Answer 4

In one test tube hydrogen is formed from the reaction of reactive metals. Using another test tube, which is turend upside down on top of the first one it can collect the hydrogen. Then a lighted splint is held underneath the test tube with hydrogen in, the hydrogen is released if a pop sound can be heard then hydrogen has been formed.

Question 5

What do metal carbonates react with acids to produce?

Answer 5

A salt, water and carbon dioxide.

Question 6

Describe a chemical test for carbon dioxide.

Answer 6

Bubble carbon dioxide through limewater, if it turns milky or cloudy white, carbon dioxide is present.

Question 7

Explain why all alkalis are bases but not all bases are alkalis.

Answer 7

All alkalis are bases as they both neutralise atoms. Alkalis are soluble in water though, but bases don’t have to be soluble in water, so bases that aren’t soluble in water aren’t alkalis but are bases.

Question 8

What is neutralisation?

Answer 8

The reaction between an acid and a base. Hydrogen ions from acid react with hydroxide ions from alkali to form water.