C5 - Chemical Changes

Question 1

Reactions:
1. Metal + acid
2. Metal hydroxide + acid
3. metal carbonate + acid
4. Metal + water
5. Metal + oxygen

Answer 1

1. Salt + hydrogen
2. Salt + water
3. Salt + water + carbon dioxide
4. Metal hydroxide + hydrogen
5. Metal oxide

Question 2

Neutralisation ionic equation

Answer 2

OH- + H+ —> H2O

Question 3

Strong vs weak vs dilute acids

Answer 3

Strong - Completely ionise in solution. High concentration of H+ ions in the acid

Weak - Don’t completely ionise in solution - reversible reactions. (Carboxyllic acids)

Dilute - low concentration of acid in water

As H+ concentration x10, pH decreases by 1

Question 4

Salt endings + charges

Answer 4

• OH^- (hydroxide)
• NO^3- (nitrate)
• SO4^2- (Sulfate)
• CO3^2- (carbonate)

Question 5

What are alkalis

Answer 5

Soluble bases
pH greater than 7
Dissociate into OH- ions in solution