Questions: Analysis of pH measurements of solutions after the addition of NaOH Initial pH pH after 5 drops NaOH pH after 10 drops NaOH Total pH change Buffer (Y or N) --- --- --- --- --- --- H2O 5.60 11.50 11.80 -6.1 Choose. Choose... 0.1 M NaCl 6.39 12.19 12.52 -6.1 Choose... Choose... High pH buffer 9.92 10.07 10.17 -0.2 Choose... Choose... Low pH buffer 4.15 4.62 4.86 -0.6 Choose... Choose..

Solution Steps

A buffer solution resists changes in pH when small amounts of acid or base are added. We need to determine which solutions act as buffers by examining the total pH change after adding NaOH.

• For \(\mathrm{H}_{2}\mathrm{O}\):

  • Initial pH: 5.60
  • pH after 5 drops NaOH: 11.50
  • pH after 10 drops NaOH: 11.80
  • Total pH change: \(11.80 - 5.60 = 6.20\)

• For 0.1 M NaCl:

  • Initial pH: 6.39
  • pH after 5 drops NaOH: 12.19
  • pH after 10 drops NaOH: 12.52
  • Total pH change: \(12.52 - 6.39 = 6.13\)

• For High pH buffer:

  • Initial pH: 9.92
  • pH after 5 drops NaOH: 10.07
  • pH after 10 drops NaOH: 10.17
  • Total pH change: \(10.17 - 9.92 = 0.25\)

• For Low pH buffer:

  • Initial pH: 4.15
  • pH after 5 drops NaOH: 4.62
  • pH after 10 drops NaOH: 4.86
  • Total pH change: \(4.86 - 4.15 = 0.71\)

• \(\mathrm{H}_{2}\mathrm{O}\) and 0.1 M NaCl have large pH changes (6.20 and 6.13, respectively), indicating they are not buffers.
• High pH buffer and Low pH buffer have small pH changes (0.25 and 0.71, respectively), indicating they are buffers.

Final Answer