acid and bases

• We measure the acidity or alkalinity of a solution using the pH scale. 
• What pH does stomach acid typically have?

  about 2
• what are two ways the pH of a solution can be measured?

  1. chemical indicator
  2. pH probe
• The pH of a solution can be measured using a type of chemical dye that changes colour, depending on the pH of the substance it's mixed with.

  This chemical dye is usually referred to as:

  indicator solution
• Universal indicator is made up of a several different indicator solutions. This means that it undergoes a smooth colour change over a wide range of pH values. 
• A pH probe electronically measures the pH of a solution.

  what are the two reasons why using a probe maybe more reliable than using an indicator?

  1. determines the colour of an indicator is subjective
  2. a probe produces a more accurate result
• A substance that forms an aqueous solution with a pH less than 7 is:


  an acid
• what ion is responsible for making an alkaline pH when dissolved in solution?

  OH-
• what are the common acids?

  1. hydrocloric (HCL)
  2. sulfuric (H2SO4)
  3. nitric (HNO3)
• what are the common bases?

  1. sodium carbonates (NaOH)
  2. calcium carbonate (CaCO3)
• what is a base?

  any substance that reacts with an acid to form a salt and water only. e.g metal oxides and metal hydroxides
• bases are soluble in water are called alkalis and they dissolve in water to form alkaline solutions e.g sodium hydroxide is a base but also an alkali beacuse it dissolves in water