Planning

Question 1

4 common indicators

Answer 1

Methyl orange
Screened methyl orange
Thymol blue
Thymolphthalein

Question 2

Methyl orange

• approx pH range
• colour in acidic soln
• colour at end pt
• colour in alkaline soln

Answer 2

3.2-4.4
In acidic - red
End pt - orange
In alkaline - yellow

Question 3

Screened Methyl orange

• approx pH range
• colour in acidic soln
• colour at end pt
• colour in alkaline soln

Answer 3

• approx pH range
  3.2-4.4
• colour in acidic soln
  violet
• colour at end pt
  grey
• colour in alkaline soln
  green

Question 4

Thymol blue

• approx pH range
• colour in acidic soln
• colour at end pt
• colour in alkaline soln

Answer 4

• approx pH range
  8-9.6
• colour in acidic soln
  Yellow
• colour at end pt
  Green
• colour in alkaline soln
  Blue

Question 5

Thymolphthalein

• approx pH range
• colour in acidic soln
• colour at end pt
• colour in alkaline soln

Answer 5

• approx pH range
  9. 4-10.6
• colour in acidic soln
  Colourless
• colour at end pt
  Light blue (if titrant is alkali)
  Colourless (if titrant is acid)
• colour in alkaline soln
  Blue

Question 6

Suitable indicators & marked pH change for:

Strong acid-strong base
Strong acid-weak base
Weak acid-strong base
Weak acid-weak base

Answer 6

4-10 all 4

3. 5-6.5 methyl orange and screened methyl orange
4. 5-10.5 thymolphthalein and thymol blue

No marked change no suitable indicator