Question

(a) How did the mL of titrant needed to reach the endpoint using the indicator you chose (Part 3) compare with the mL of titrant needed to reach the equivalence point (Part 2)?

(b) What does this say about these two methods? Is one a better means of monitoring a titration than the other? Why or why not?

Table 1: Indicator, pH Range, and Color Change

Flask	Indicator	Amount Needed for Reaction to Complete	pH Range	pH at Color Change	Color (Initial : Final)
1	Bromothymol blue	6	6.0-7.6	7.1	Blue/clear-yellow
2	tumeric	6	7.4-8.6	5	Lil red-Orange:yellow
3	Mehyl orange	20	2.5-4.4	8	Orange:pink

mL citric acid need for neutralization	Neutralization ph	Moles of citric acid used
.50ml	11.57

Table 2: Citric Acid Sudsy Ammonic Titration Data Indicator Used

Citric Acid Added

pH

Color

0.0

10.25

Orange

1.25

9.64

Orange

.25

9.21

Orange

.375

8.56

Oange

.5

6.23

Orange

.625

5.43

Orange

.75

4.96

Orange

.875

4.60

Orange

1

4.35

Orange

1.125

4.13

Orange

1.25

3.9

Pink-orange

1.375

3.75

Pink-orange

1.5

3.64

Pink

1.625

3.544

Pink

1.75

3.47

Pink

1.875

3.33

pink

2

3.19

pink

mL citric acid need for neutralization 2mL

Neutralization 3.19ph

Moles of citric acid used

Answer 1

(a) The indicator are the chemical compounds which are used to determine end point during titration by colour changing.

in part 3 methyl orange indicator is used which shows colour change at ph 8 and convert from orange to pink colour and the indicator used in part 2 is turmeric which changes from lil red-orange to yellow at ph 7.4-8.6. As the amount of citric acid needed is 20 ml for methyl orange i.e more amount of acid is needed to change the ph of the solution which shows end point by changing colour and the amount of citric acid needed for turmeric is 6ml to change the ph. More amount is needed for part 3 and less amount is needed for part 2 .  

(b) part 2 is a better way to monitoring a titration as we can easily distinguish the colour change from red-orange and yellow then orange to pink and also there is a more ph range