Paper 3: Required practical 1 - Making up a standard solution and carrying out an acid base titration

Question 1

How do you make a standard solution?

Answer 1

1. Measure using a balance the mass of solid required
2. Transfer this into a volumetric flask and rinse the remaining weighing bottle content (with distilled water) into the flask so no solid is lost
3. Add a volume of distilled water to dissolve the solid - swirl to mix
4. Add more distilled water up to the line on the volumetric flask
5. Invert mulitple times to mix

Question 2

What equipment is used to carry out a titration?

Answer 2

• Pipette and pipette filler - accurately measure out the volume of a reactant before transferring it to a conical flask
• Burette - add small volumes of one reactant to the other reactant (until the reaction has reached completion)

Question 3

How do you carry out a titration?

Answer 3

1. Once the pipette has been used to place on reactant into the conical flask, fill the burette with the other reactant - record initial volume
2. Add a few drops of indicator to the conical flask
3. Open the burrette rap and allow the reactant to flow into the conical flask, swirling it to mix the contents
4. Close the burette tap once the expected colour change occurs - use a white tile so the colour change is easy to identify
5. Record the final burette volume
6. Repeat until you get concordant results, then calculate a mean titre

Question 4

Why are acid-base indicators used?

Answer 4

To detect when a reaction reaches completion, usually by the presence of a colour change

Question 5

What are concordant results?

Answer 5

Titres that are within 0.1 cm^3 of each other