Basic concepts in chemistry

1. Seminar chemistry form 5 ( Revision for topics) i) Electrochemistry ii) Carbon compound iii) Thermo chemistry Date : 5 April 2011 ( Tuesday)

2. 1)

3. Refer to the diagram above: Electrolytic cell Anode (positive electrode) Cathode (negative electrode) oxygen gas Copper metal Cell P Electrode M Electrode N Name of cell Label anode and cathode State products

4. Bubble of colourless gas that ignites the glowing wooden splinter 4OH - O 2 + 2H 2 O + 4e Brown solid is formed Cu 2+ +2e Cu State observations Write ionic equations

5. Electrical energy Chemical energy Cell P State change of energy

6. Refer to the diagram above: Voltaic cell ( Daniel cell) Anode (NEGATIVE ELECTRODE) Cathode ( POSITIVE ELECTRODE) Zinc ion Copper metal Cell Q Electrode R Electrode S Name of cell Label anode and cathode State products

7. Zinc Electrode becomes thinner Copper electrode becomes thicker Zn Zn 2+ + 2e Cu 2+ + 2e Cu State observations Write ionic equations

8. Chemical energy Electrical energy Cell Q State change of energy

9. 2)

10. Answer the following questions K + , H + , Cl - , OH - Cathode Anode Electrode P Electrode Q a)State all ions present b)Label anode and cathode

11. H + Cl - Hydrogen gas Chlorine gas K + ,H + Cl - ,OH - Cathode Anode b)Label anode and cathode c)State ions attracted to d)State ions discharged e)State products and what is the factor involved?

12. Hydrogen gas Chlorine gas Position of ions in ECS Concentrations of ions in solution e)State products and what is the factor involved? Factor involved

13. Position of hydrogen ion is lower than potassium ion in Electrochemical Series Chloride ion is more concentrated than hydroxide ion f)Give a reason why you have the product as mentioned above?

14. 2H + + 2e H 2 2Cl - Cl 2 + 2e g)Write ionic equations

15. -Bubble of colourless gas is released. - Bring a lighted wooden splinter to the mouth of test tube, a ‘pop’ sound is produced -Bubble of yellowish gas is released. -Bring a piece of moist blue litmus paper to the mouth of the test tube. -Blue litmus paper turns red then bleached h)State observations and how do you test the products?

16. Hydrogen gas. Position of ion in Electro chemical series Oxygen gas. Position of ion in Electro chemical series i)If the experiment is repeated with concentration of solution 0.001 mol dm -3 . State the products . And what is the factor involved?

17. 3) Organic reaction Ethene ethanol Ethyl ethanoate CO 2 + H 2 O Ethanoic acid Reaction 2 Reaction 1 Reaction 4 Reaction 3 Reaction 5 Reaction 6

19. Heat in excess oxygen C 2 H 5 OH + 3O 2 2CO 2 + 3H 2 O Reaction 1 c)Conditions (if any) d)Equations

21. Pass ethanol over heated porcelain chips C 2 H 5 OH C 2 H 4 + H 2 O Reaction 2 c)Conditions (if any) d)Equations

23. -Catalyst,H 3 PO 4 -Temperature,300 o C -Pressure, 60atm C 2 H 4 + H 2 O C 2 H 5 OH Reaction 3 c)Conditions (if any) d)Equations

25. warm the mixture C 2 H 5 OH+ CH 3 COOH CH 3 COOC 2 H 5 + H 2 O Reaction 4 c)Conditions (if any) d)Equations

27. warm the mixture C 2 H 5 OH+ CH 3 COOH CH 3 COOC 2 H 5 + H 2 O Reaction 5 c)Conditions (if any) d)Equations

29. warm the mixture C 2 H 5 OH+ 2[O] CH 3 COOH + H 2 O Reaction 6 c)Conditions (if any) d)Equations

30. B)Draw diagram for experiment to carry out for reaction 2

31. Describe the coagulation of latex when exposed to air

35. 5) A student obtained the data to determine heat of precipitation of PbSO4 Highest temperature : 30.5 0 C Solution Vol (cm3) Conc (moldm-3) Initial temp ( 0 C) Pb(NO 3 ) 2 50 0.5 27.4 Na 2 SO 4 50 0.5 27.6

48. 7) State the diff betw heat change and the heat of reaction Heat absorb , heat released -Heat of Precipitation -Heat of displacement -Heat of neutralisation -Heat of combustion HEAT CHANGE HEAT OF REACTION A) OTHER NAMES Depends on name of reactions :

49. 7) State the differences between heat change and heat of reaction HEAT CHANGE HEAT OF REACTION B) FORMULA USED H= mC ϴ ∆ H = mC ϴ mol C)UNIT Joule Kilo Joule/ mol D) SYMBOL none ∆ H E) SIGN No sign Either + for endothermic rex or – for exothermic rex