Acids, bases and salts

Question 1

What is an acid?

Answer 1

a substance which has the ability to donate H+ ions

/ An H+ donor

Question 2

How does an acid react with a metal?

Answer 2

Acid + Metal -> Salt + hydrogen
[ONLY IF the metal is more reactive than hydrogen]

OBSERVATIONS:

• effervescence of a colourless gas
• If a metal is reactive the reaction is too violent to be carried out safely

Question 3

How does an acid react with a metal hydroxide?

Answer 3

Acid + Metal hydroxide -> salt + Water

Question 4

How does an acid react with a metal oxide?

Answer 4

Acid + metal oxide -> Salt + water

Question 5

How does an acid react with a metal carbonate?

Answer 5

Acid + Metal carbonate -> Salt + Water + Carbon dioxide

OBSERVATIONS:
-Effervescence of a colourless gas

Question 6

What is meant by the term “strong acid”? Give an example

Answer 6

-An acid that undergoes full dissociation in water, forming its constituent ions
E.g, hydrochloric/ sulfuric/ nitric acid

Question 7

What is meant by the term “weak acid”? Give an example

Answer 7

-An acid that only slightly dissociates into its constituent ions in solution
E.g, Carboxylic acids

Question 8

Give 3 examples of non metal oxides producing an acid

Answer 8

REACT WITH WATER:

1. SO2(g) + H2O(l) → H2SO3(aq)
2. 2NO2(g) + H2O(l) → HNO3(aq) + HNO2(aq)
3. CO2(g) + H2O(l) → H2CO3(aq)

Question 9

What is pH?

Answer 9

A measure of H+ concentration in aqueous solution

-The higher the H+ conc, the lower the pH/ more acidic the solution

Question 10

What is the relationship between the vales for pH and conc of H+

Answer 10

A change of 1 on the pH scale corresponds to a change by a factor of 10 in H+(aq) ion concentration

Question 11

What is meant by the term “monoprotic acid”? Give an example

Answer 11

-They are only able to donate 1 acidic H+ (aq) ion per acid molecule

E.g, HCl, HNO3, CH3COOH

Question 12

What is meant by the term “diprotic” acid

Answer 12

• They are able to donate 2 acidic H+ ions per molecule;
• donate more than 1 mole of H+ ions

E.g, H2SO4

Question 13

What is meant by the term triprotic acid?

Answer 13

• They are able to donate 3 acidic H+ ions per molecule;
• donate more than 1 mole of H+ ions

E.g, H3PO4

Question 14

What is a base?

Answer 14

• a substance that can accept H+ ions

- able to form OH−(aq) in solution

Question 15

What is meant by the term “strong base”? Give an example

Answer 15

A base (alkali) which undergoes full dissociation in water, forming its constituent ions

E.g, NaOH, KOH

Question 16

What is meant by the term “weak base”? Give an example

Answer 16

A weak base that only partially forms ions in solution

E.g, Ammonia (NH3)

Question 17

How do metal hydroxides react with water to form alkaline solutions?

Answer 17

1) NaOH(s) + H2O(l) → Na+(aq) + OH−(aq)

2) Ca(OH)2(s) + H2O(l) ⇌ Ca2+(aq) + 2OH−(aq)

Question 18

How do metal oxides react with water to form alkaline solutions?

Answer 18

1) Na2O(s) + H2O(l) → 2Na+(aq) + 2OH−(aq)

2) BaO(s) + H2O(l) → Ba2+(aq) + 2OH−(aq)

Question 19

What type of reaction occurs when an acid reacts with a base?

Answer 19

NEUTRALISATION

Question 20

Describe the way in which an acid and base react

Answer 20

-Neutralisation reaction takes place
-It is a process of bond forming:
H+(aq) + OH−(aq) → H2O(l)
-Bond forming releases energy
-Is often an EXOthermic reaction