Acids & Bases

• pH is a measure of how acidic or alkaline a solution is
• pH is 0-14, 7 is neutral
• Stomach acid has a pH of 2
• Bleach has a pH of 12
• Indicators change colour depending on the pH of the solution.
• Universal indicator ranges from deep red, to yellow, to green, to blue to purple.
• A pH probe gives a numerical value of pH on a pH meter. This is much more accurate and precise than universal indicator.
• Acid


  Any substance that forms an aqueous solution with a pH of less than 7
• Acids release hydrogen ions in water which makes the solution acidic
• Bases


  Any substance with a pH greater than 7
• Alkalis


  A base that dissolves in water to form a solution with a pH greater than 7
• Alkalis form OH- ions in water
• Reacting an acid and base together will cause a neutralisation reaction, this always produces salt and water.