Bases and Alkalis

Question 1

What is a base?

Answer 1

-any metal oxide or hydroxide that reacts with an acid to produce salt and water only (neutralization)

Question 2

Examples of bases

Answer 2

Metal oxides: sodium, zinc, calcium, iron (III, copper (II)

Metal hydroxides: sodium, zinc, calcium, iron (III), copper (II)

Question 3

What is an alkali?

Answer 3

• a soluble base which dissolves in water to produce OH- ions
• not all bases are alkali

Question 4

Properties of alkali

Answer 4

• feel soapy, bitter taste
• turn red litmus paper blue
• react with acids to form salt and water only (neutralization) OH-(aq) + H+(aq) —> H2O
• warmed with ammonia salts to produce ammonia gas
• react with a soln of one metal salt to give another metal salt and metal hydroxide

Question 5

Properties of alkali 4: warmed with ammonia salts to produce ammonia gas

Answer 5

• alkali + ammonium salt —> salt + water +ammonia
• ammonium salt contains NH4 + ion
• ammonia (NH3), turns red litmus paper blue

Question 6

Properties of alkali 5: react with a sol of one metal salt to give another metal salt and metal hydroxide

Answer 6

alkali (containing metal A) + salt (of metal B) —> metal hydroxide (of metal B) + salt (of metal A)

Question 7

Uses of bases and alkali

Answer 7

• Magnesium oxide : relieve gastric pain

- Sodium, potassium hydroxide: soap