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(a) The indicator are the chemical compounds which are used to determine end poi

ID: 700231 • Letter: #

Question

(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

Explanation / Answer

(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

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