acids and bases
1) Describe the characteristic properties of Acids
- An acid is a compound which when dissolved in water produces hydrogen ions (H+).
- Strong acids completely ionize in water producing lots of H+ ions.
- Weak acids partially ionize in water producing few H+ ions.
- Acids turn blue litmus indicator paper (or solution) red
- Have pH 1 to 6
- Acid + metal → salt + hydrogen gas
- Acid + base → salt + water
- Acid + metal carbonate → salt + carbon dioxide + water
2) Describe the characteristic properties of Bases/Alkaline
- Bases are insoluble substances which neutralize acids to form a salt and water only.
- Alkaline are soluble bases.
- An alkaline is a compound which when dissolved in water produces hydroxide ions (OH-).
- Strong alkalis completely ionize in water producing lots of OH- ions.
- Weak alkalis partially ionize in water producing OH- ions.
- Alkalis turn red litmus indicator paper (or solution) to blue.
- Have pH 8 to 14.
- Base + acid → salt + water (+ CO2 when base is a metal carbonate)
- Base + ammonium salt → salt + ammonia gas + water
3) Explain the importance of controlling acidity in Soil
- Crops unable to grow in acidic soil.
- Farmers use lime (calcium oxide) to neutralize acid soils.
- Colorless in acid. Pink in alkaline.
- Red in acid. Yellow in alkaline.
5) Classify Oxides
- Form basic oxides, exhibit basic properties, eg. magnesium oxide; or
- Form amphoteric oxides, exhibit acidic and basic properties, e.g. lead oxide, aluminum oxide, zinc oxide.
- Form acidic oxides, exhibit acidic properties, e.g. sulphur oxide and carbon dioxide; or
- Form neutral oxides, do not react with acid or bases, e.g. water and carbon monoxide.
preparation of salts
6) Preparation of Salts
All sodium, potassium, ammonium salts and nitrates
Except silver and lead
Except barium, lead and calcium
Potassium, sodium and ammonium carbonates
All other carbonates
Add Insoluble Base to prepare soluble non-SPA salts:
- Add insoluble base to acid and heat gently, it will dissolve
- Keep adding until no more dissolves (reaction is done)
- Filter out the insoluble (excess) base
Precipitation to prepare insoluble salts:
- Mix the two soluble salts, so they react together
- Filter the mixture to separate the products produced (soluble and insoluble salt produced)
- Wash the insoluble salt on the filter paper
- Dry the insoluble salt in a warm oven
identification of ions and gases
7) Identification of ions and gases
Test for Cations:
Flame Test for Metal Ions:
Test for Anions:
Test for Gases: