Gas Forming Reactions

Question 1

What are the products of gas forming reactions?

Answer 1

Look for these gases:

CO₂ (carbon dioxide)

NH₃ (ammonia)

SO₂ (sulfur dioxide)

H₂S (hydrogen sulfide)

HCN (hydrogen cyanide)

Question 2

How are these gases formed?

• CO₂ (carbon dioxide)
• SO₂ (sulfur dioxide)
• H₂S (hydrogen sulfide)
• NH₃ (ammonia)

Answer 2

• CO₂ (carbon dioxide): metal carbonate (CO₃^2-) or bicarbonate (HCO₃-) + acid
  
  • H₂CO₃ = H₂O + CO₂
• SO₂ (sulfur dioxide): metal sulfite (SO₃^2-) + acid
  
  • H₂SO₃ = H₂O + SO₂
• H₂S (hydrogen sulfide): metal sulfide (S^2-) + acid
• NH₃ (ammonia): ammonium salt (NH₄+) + strong base
  
  • NH4OH = H₂O + NH₃

Just do the exchange reactions and release the gas when you see it.