3-investigating pH(neutralisation)

• acids are sources of?

  hydrogen ions
• alkalis are sources of?

  hydroxide ions
• what is a neutral solutions pH?

  7
• what happens when there is a higher concentration of hydrogen ions in an acidic solution?


  lower pH
• what happens if there is a high concentration of hydroxide ions in an alkaline solution?


  higher pH
• what apparatus will be needed?

  measuring cylinder

  beaker

  glass rod

  spatula

  universal indicator paper
• what is step 1?

  measure the dilute Hcl using a measuring cylinder and put it in the beaker
• what is step 2?

  dip a clean glass rod into the contents of the beaker

  use it to transfer a drop of liquid to a piece of universal indicator paper on a white tile

  wait 30s then match colour to pH chart

  record estimated pH
• what is step 3?

  add a levelled spatula of calcium hydroxide powder to the beaker
• what is step 4?

  stir thoroughly, then estimate the pH
• what is step 5?


  repeat steps 3 n 4 until there are no more changes in pH showing the solution has become neutralised
• what is the best piece of apparatus to measure the volume of hydrochloric acid?


  measuring cylinder
• how do you use universal indicator paper to measure the pH of the solution?

  use a pH chart and estimate the colour
• why is it necessary to stir the mixture when the calcium hydroxide powder is added?


  ensures uniform reaction takes placeleading to consistent and reliable results
• how do you know when the hydrochloric acid is exactly neutralised?


  if its green n pH of 7