Higher Chemistry Unit 4

Question 1

Standard Solution

Answer 1

Standard Soluion is a solution of accurately known concentration.

Dissolve the accurately measured mass of solid in a small volume of deionised water.

Transfer the solution to a standard flask, carefully rinsing the beaker out.

Make up the solution to the line on the standard flask, using a dropper for the last few drops so that the bottom of the menscus sits on the line of the standard flask.

Question 2

Distilation

Answer 2

Used to separate a mixture of liquids with different boiling points

Liquid mixture is heated just above the boiling point of one of the liquids.

Gas travels through the condenser, cooling the liquid.

Separated liquid is collected in a beaker.

Question 3

Titration

Answer 3

Used to find the concentration of the unkown solution

1. A burrete is rinsed and filled with standard soltuon to the 0 mark.
2. A pipette is rinsed then filled with solution of unkown concentration up to the graduation mark and then emptied into a conical flask.
3. The conical flask is placed on a white tile and an indiactor is added .
4. The solution of the burette is added to the conical flask until the indicator changes ( the end point)
5. The volume used is recorded and process is repated until titre results are within 0.02cm
6. Average of concordent results are used to calculate unkown concetration.

Question 4

Weighting by difference

Answer 4

1. Place a beaker on a balance and measure out a mass of solid
2. Record the mass of the beaker and the solid (TOTAL MASS)
3. Transfer the solid into a second container - to use for your experiment
4. Reweigh the now ‘empty’ beaker and any leftover solid (LEFTOVER MASS)
5. The accurate mass of solid trnasferred is the difference between the two recorded masses.
   MASS USED = TOTAL MASS - LEFTOVER MASS