Intro To Planning

Question 1

What are the general steps to writing the Procedure? What are things you need to include

Answer 1

1. Number all steps
2. Don’t include calculations in Procedure unless qn asked you to
3. Phrase all steps as imperatives.
4. Specify:
   (A) Apparatus used, and the capacity of the apparatus (when it is first introduced)
   - note: measuring cylinder and pipette need to specify for all steps cos it can have diff capacities
   (B) The volume measured (if known), with appropriate precision of the apparatus
   - burette = 2dp, mass balance 3dp, measuring cylinder 1dp, pipette 1dp
5. Sometimes it is necessary to include adverbial clauses which provide information about the purpose of the step, or the expected observations
6. For timed based experiments, specify time at which action is to be executed

Question 2

What types of VA planning can there be? [3]

Answer 2

1. Titration
2. Preparing standard solution with solid reagent
3. Dilution of liquid sample

Question 3

Describe the planning procedure for dilution of liquid sample

Answer 3

1. Using a burette/pipette, transfer 25.00cm3 / 25.0cm3 of FA1 into a 250cm3 volumetric flask
2. Record initial and final burette readings
3. Add deionised water into volumetric flask until the liquid level reaches the graduation mark
4. Stopper the flask, invert a few times to ensure a homogenous solution

Question 4

Describe the preparation of standard solution with solid sample

Answer 4

1. Using an electronic balance Weigh the mass of the weighing bottle and FA1 (its contents) and record it.
2. Empty the contents of the weighing bottle into a 100cm3 beaker. Reweigh the weighing bottle, record its mass and calculate mass of FA1 used.
3. Add about 50cm3 of deionised water to the beaker, stir with a glass rod to ensure that solid has completely dissolved.
4. Transfer solution in beaker into 250cm3 volumetric flask. Rinse beaker with deionised water and transfer washings into volumetric flask as well
5. Add deionised water into the volumetric flask till liquid level reaches graduation mark
6. Stopper flask and invert a few times to ensure homogenous solution

Question 5

Describe the planning procedure for titration

Answer 5

1.Fill a 50cm3 burette with titrant. Record the initial burette reading
2. Pipette 25.0cm3 of FA2 with unknown conc into a 250 cm3 conical flask placed on a white tile. Add 2 drops of indicator.
3. Add FA1 from burette into conical flask with continuous swirling. Add FA1 dropwise towards the end point of the titration. Stop the addition when 1 drop of FA1 turns the solution from __colour__ to _colour__
4. Record final burette reading and calculate titre volume used.
5. Repeat the above steps till 2 titre volumes within +/- 0.1cm3 of each other is obtained