Chemistry/Acids and Bases Prep
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Equipment that must be available
- 24 plastic wells plates (containing 12 large wells each)
- 1 vial of neutral litmus paper
- 12 pH colour cards
- 24 plastic wells plates (containing 12 large wells each)
Solutions
6 small dropper bottles of each of:
- bromthymol blue indicator, labeled “Bromthymol blue”
- methyl red indicator, labeled “Methyl red”
- phenolphthalein indicator, labeled “Phenolphthalein”
- universal indicator, labeled “universal indicator”
6 – 100 mL bottles of each of:
- HCl (0.1 M), labeled “Highly Acidic”
- NaOH (0.1 M), labeled “Highly Basic”
- pH 7 buffer, labeled “NEUTRAL”
- pH 8 buffer, labeled “A”
- pH 5 buffer, labeled “B”
- pH 7 buffer, labeled “C”
- pH 6 buffer, labeled “D”
- pH 10 buffer, labeled “E”
- pH 4 buffer, labeled “F”
- pH 9 buffer, labeled “G”
Check that the following results are obtained when one drop of each indicator (or small piece of litmus) is added to one pipetful (using smallest plastic pipet available) of each liquid to be tested. If these results do not occur, remake the buffer or check its pH.
Indicator | pH = 4 | pH = 5 | pH = 6 | pH = 7 | pH = 8 | pH = 9 | pH = 10 |
---|---|---|---|---|---|---|---|
Neutral litmus | pale pink | pale pink | pale pink | purplish red | reddish purple | purple | purple |
Methyl red | pink | pinkish orange | slightly orange yellow | yellow | yellow | yellow | yellow |
Bromthymol blue | yellow | yellow | slightly greenish yellow | green | blue | blue | blue |
Phenolphthalein | colourless | colourless | colourless | colourless | colourless | slightly pink | pink |
Universal Indicator | orangish red | orange | yellow | yellowish green | green | blue | bluish purple |