Chemistry chemical changes

• The pH scale goes from 0 to 14
• The pH scale is a measure of how acidic or alkaline a solution is
• Lower pH= acidic
• Higher pH= alkaline
• A neutral substance has a pH of 7 which is a green colour
• An indicator is a dye that changes colour based on its pH
• Wide range indicators gradually change over a broad range of pH. They estimate the pH of a solution
• A pH probe attached to a pH meter measures the pH electronically. It gives an exact reading of the pH so its more accurate
• Acids and bases neutralise each other
• Acid forms aqueous solutions with a pH less than 7. They form H+ ions in water
• A base has a pH greater than 7
• An alkali is a base that dissolves in water to have a pH greater than 7. Alkalis form OH- ions in water.
• The reaction between acids and bases is neutralisation
• acid+base- salt+water
• H+ + OH- - H2O
• Inidcators are used to show when a neutralisation reaction is over.
• Neutralisation reactions of strong acids and alkali are used to calculate the concentration of an acid or alkali by titration