Chemistry practical 2

Question 1

Aim of this experiment

Answer 1

To make a solution of a known concentration of ACID and use it to find the concentration of SODIUM HYDROXIDE solution

Question 2

How to prepare the standard solution: the solid acid

Answer 2

Weigh an empty test tube
Spoon approximately 2.5g of sulfuric acid into the tube and reweigh both the tube and acid

Question 3

How to prepare the standard solution: addition of the water to solid acid

Answer 3

Dissolve the weighed acid in 100cm3 of water in a beaker

Question 4

How to prepare the standard solution: volumetric flask

Answer 4

Transfer washings and the solution into a volumetric flask

Question 5

How to prepare the standard solution: dissolving water

Answer 5

Make up the solution to around 250cm3 in the volumetric flask with deionised water

Question 6

Step 1 of the actual titration

Answer 6

Rinse the burette with solution of sulfamic acid
Because any remaining liquids in the burette may dilute the standard solution
Do not use water = diluted

Question 7

Step 2 of titration

Answer 7

Rinse volumetric pipette with sodium hydroxide solution
If we use water, then this will dilute the solution because this well effect how much NaOH we add thus how may moles we have

Question 8

Step 3 of titration

Answer 8

Pour 25cm3 aliquot of NaOH into conical flask
And methyl orange indicatior

Question 9

Step 4 titration

Answer 9

Titrate standard solution of sulfamic acid against the unknown concentration of NaOH in flask

Question 10

Can we wash the conical flask with water?

Answer 10

Yes because the moles of NaOH have already been measured so remaining water molecules will not change number of moles

Question 11

Step 5 if titration

Answer 11

Continue until 2 concordant titres have been obtained

Question 12

Colour change of methyl orange

Answer 12

Red in acid
Yellow in neutral/alkali
So a colour change will be yellow to red

Question 13

Colour change of phenolphthalein

Answer 13

Colourless in acid
Pink in neutral/alkali
So a colour change will be from pink to colourless