All Experiments

Question 1

How would you carry out an experiment to determine the water of crystallisation

Answer 1

• weigh an empty crucible
• add the hydrated salt into the weighted crucible then weight it
• use a pipe-clay triangle supported on a tripod. Then place the crucible on top.
• Heat the crucible and contents gently for about a minute. Then heat it strongly for a further three miniutes.
• leave the crucible to cool. Then weigh the crucible and anhydrous salt.

Question 2

What assumption do we make when we conduct the hydrated salt experiment and how can you ensure the experiment is accurate as possible?

Answer 2

Assumption 1 - All of the water has been lost. If the hydrated and anhydrous forms have different colours, then it is safe to assume all the water has been lost. If the hydrated and anhydrous forms a similar colours , then it is best to heat to constant mass.

Assumption 2 - no further decomposition
Many sales second or further when heated; for example, if heated very strongly, copper (II) sulfate decomposes to form black copper (II) oxide. This can be difficult to judge if there is no colour change.

Question 3

How do you make a standard solution?

Answer 3

1) The solid is first weighed acurately using a balance.
2) Transfer solid from weighing boat to beaker. Wash any solid left behind into the beaker using deionised water.
3) Dissolve your solid fully using deionised water. Stir to ensure the solid is dissolved fully.
4) Transfer solution to volumetric flask. Use a funnel to avoid spillage and rinse the beaker, glass rod and funnel into the flask to ensure most of the solution is transferred.
5) Use more deionised water to fill to the graduation line. Be careful not to go above this line, or else it will be too diluted! Use a pipette to fill to the line when you get near. Make sure the base of the meniscus touches the mark
6) Add a stoper. Then invert a flask a few times. This ensure the solution is thoroughly mixed and ready to use.

Question 4

Write down the methods to carry out a titration experiment

Answer 4

1. Using a pipette, measure the volume of a solution
2. Add the solution into a conical flask and add an indicator into it
3. Add the other solution into a burette and record the volume to the nearest 0.05cm^3
4. Slowly add the solution in the burette into the conical flask
5. Swirl the mixture continuously until the endpoint is reached
6. Record the final burette reading to nearest
7. 05cm^3 to obtain titre
   7) run a quick trial
8. Repeat until concordant results are obtained - agreeing to within 0.10cm^3