Paper 3 Last Minute

• Measure ~6g of salicylic acid into a conical flask • Add ~10cm³ of ethanoic anhydride and 5 drops of concentrated sulphuric acid • Swirl the mixture and place the flask in a warm water bath for 20 or so minutes • Allow the flask to cool and then pour the contents into a beaker. Add said beaker into cold water with ice. • Wait for the aspirin to crystalise. Recover the aspirin using Buchner filtration and leave it to dry.

• Add the impure solid to a beaker and dissolve it with the minimum amount of hot solvent, to ensure a minimal loss of product. • As the solution cools, the pure organic solid crystalises out. The impurities are left behind in the solution. • The product crystals are then removed by Buchner filtration. • The product is then washed using cold distilled water and then left to dry on filter paper. • Insert the solid into a melting point identifier, using a melting point tube. • If the solid melts at the melting point given in the data booklet, it is pure. If it does not, it is impure.

• Use a pipette and pipette filler to transfer 25cm³ of the standard solution to a 250cm³ conical flask • Add 3 drops of methyl orange indicator to the flask • Fill the burette with hydrochloric acid, ensuring that there is no air bubbles and record the initital burette reading. • Add the hydrochloric acid from the burette to the conical flask. As the end point is approaching, add the acid drop-by-drop. The solution will change from yellow to orange. • Record the final burette reading and repeat until concordant results are obtained.

• The outer electrons are further away from the nucleus and experience greater shielding from inner shells • There is a weaker attraction between the nucleus and outer electrons, so less energy is required to remove them

• Boiling point increases down group 7. • Halogens are di-atomic molecules at room temperature. • As such, they have a simple molecular structure with weak London Forces between the molecules. • The larger the molecule, the more electrons. This leads to more London Forces and a higher boiling point.

• The halogens become less reactive down the group. • Atomic radius increases. • There are more inner shells so shielding increases. • There is less nuclear attraction to attract an electron from another species.

• Reactivity increases. • Atomic radius increases, so more shielding. • The nuclear attraction between the electrons and the nucleus decreases, so it’s easier to remove outer electrons.

• First and second ionisation energies decrease down the group. • Attraction between the nucleus and outer electrons decrease. • Atomic radius increases and there is increased shielding.