Presentation on theme: "A Level questions. Moles A student took 1g of Citric acid C 6 H 8 O 7.xH 2 O and dissolved it in 100cm 3 of water. 10cm 3 of this solution neutralised."— Presentation transcript:
Moles A student took 1g of Citric acid C 6 H 8 O 7.xH 2 O and dissolved it in 100cm 3 of water. 10cm 3 of this solution neutralised 14.3cm 3 of 0.1M NaOH Citric acid is a tribasic acid and can be written as H 3 Y a.Write a balanced equation between citric acid and NaOH b.Show that the number of moles of citric acid that was neutralised was 4.77x10 -4 c.Hence calculate the anhydrous mass of citric acid present in the 1g of hydrated citric acid d.Hence work out the value of x in C 6 H 8 O 7.xH 2 O
Trends Explain why a.K has a lower Boiling Point than Ca b.Si has a higher Boiling Point than P c.Mg is a worse conductor than Al d.F atoms are smaller than N atoms e.F atoms have a lower first IE than Ne atoms but a higher first IE than Na atoms f.H 2 O has a lower melting point than Na 2 O but a higher melting point than CO 2
Shapes Draw dot ‘n’ cross diagrams of SO 3, Cl 2 S, PF 3, SiCl 4 Predict the shape of these 4 molecules Draw dot ‘n’ cross diagram of NaCl, MgCl 2 Explain why MgCl 2 has the higher Melting Point Explain why neither conduct electricity when solid but both do when molten.
Reactivity Why is Mg less reactive than Ca? How could you show this? Why is I 2 less reactive than Cl 2 How could you show this Which decomposes at a lower temp CaCO 3 or MgCO 3 ?
Observations What do you see when you (write a balanced equation to show obs) a.Add CaCO 3 to HCl b.Add CaO to HCl c.Add AgNO 3 to NaBr followed by i.Dil NH 3 ii.Conc NH 3 d. Add AgNO 3 to NaCl followed by i.Dil NH 3 ii.Conc NH 3 e. Add AgNO 3 to NaI followed by i.Dil NH 3 ii.Conc NH 3