acids and bases

• acid is a substance that produces hydrogen ions , H+, in aqueous solutions
• acids

  1. have a sour taste
  2. dissolve in water to form solution that conduct electricity
  3. turns blue litmus paper into red
• metal + acid -> salt + hydrogen

  base + acid -> salt + water

  carbonate+acid-> salt + water + carbon dioxide
• stronger acid = more H+ ions produced
• alkali/ base - substances that produce OH- ions when dissolved in water
• alkalis turn red litmus paper blue
• pH scale ranges from 0-14 (7 being neutral)
• acidic solutions have pH below 7
• basic solutions have pH above 7
• how to test for hydrogen gas

  test : insert lighted splint

  Observation : the lighted splint will extinguish with a pop sound
• how to test for carbon dioxide

  Method : bubble the gas through lime water

  observation : white precipitate forms in line water
• Oxide (O)

  hydroxide (OH)
• Alkalis

  1. They feel soapy
  2. Have a bitter taste
  3. React with acids to produce water + salt(neutralisation reaction)
  4. The ionic equation for neutralisation reaction is H+(aq)+ OH-(aq)-> H2O (l)
• How to test for ammonium gas

  method : use a moist red litmus paper

  Observation: gas turns moist red litmus paper blue
• Calcium hydroxide and calcium oxide : reduces excess acidity in the soil
• Soil needs to be slightly acidic