Mandatory Student Experiment No. 12 Flashcards

1
Q

Describe how the 25 cm cubed sample of the original bleach solution was diluted to exactly 500 cm cubed
(4 points)

A

Pipette 25 cm cubed of bleach into a 500 cm cubed volumetric flask
Add deionised water until near the mark
Add deionised water dropwise until bottom of the meniscus is up to mark
Read flask at eye level
Stopper and invert several times

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2
Q

What colour developed when the potassium iodide and the sulfuric acid reacted with the diluted bleach in the conical flask?

A

Reddish-brown colour

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3
Q

Give two reasons why excess potassium iodide was used

A

So that all the bleach reacted to ensure the max production of iodine
To keep the iodine in solution

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4
Q

What was the purpose of standing the conical flask on a white tile during the titrations?

A

So that the colour change could be more easily seen

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5
Q

Name the indicator used in the titrations and state the colour change observed at the end point

A

Starch

Blue-black to colourless

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