Question three…… Thursday, Aug 23 2007 

HSC style Q's davisdag 12:32 pm

First though, a guide to answering question two….

…….as it says describe – you can’t just name.

* ionic bonding in which an electron is transferred from sodium to chlorine forming sodium ions and chloride ions. (1 mark)

* ion packing in an orderly array – draw a diagram ! (this is a great way to support an explanation!!)  – (1 mark)

* Explain each of the three properties (1 mark each).

Michel did great , yet again………she’s getting lonely out there………have a go!

Now question three……

Explain with an example what is meant by dynamic equilibrium. In addition, explain how the dynamic nature of one particular equilibrium could be demonstrated. (4 marks)

good luck…….there will be a question 4 and 5 over the weekend………

 

More mole answers Thursday, Aug 23 2007 

Answers to questions davisdag 12:21 pm

14. C

15. A

16. B

17. D

18. C

19. B

20. B

21. C

22. C

23. B

24. C

25. A

hope that is ok……..now any difficulties need to be dealt with straight away…..you’ll get a new sheet next week.

 

Mole set 4 Saturday, Aug 18 2007 

Answers to questions davisdag 12:15 am

OK guys……here are the answers to the questions I gave ya all on Thursday……now I haven’t had a chance to double check so if any look fishy LOL! leave a comment and I will do a quick calculation or two to check…

1. B

2. A

3.B

4. A

5. C

6. C

7. B

8. A

9. A

10. B

11. C

12. D

13. C

How did you go??????

 

Question two……. Tuesday, Aug 14 2007 

HSC style Q's davisdag 9:34 am

Here we go……

Describe the chemical bonding in sodium chloride.Explain how it leads to the compound having a high melting point, being hard and brittle, and being a non-conductor of electricity as a solid but a conductor as a liquid.

5 marks

 Remember……submissions for question one are finished…..look at the comments for other students answers….michel’s is especially good…….The marking guidelines for this question would have gone…each technique would earn one mark = 4 marks….for identifying the properties of the solids used to separate the solids in each technique  = 1 mark……..identifying the properties of the liquids used for separating the liquids in each technique would have earned a mark

 

Answers to bonding questions…… Friday, Aug 10 2007 

Water davisdag 5:37 am

7.

b) Paraffin wax is a non-polar hydrocarbon with long hydrocarbon chains. Water cannot form strong bonds enough to dissolve it. The chemical bonds between the atoms of silica are so strong that the solvent cannot break and establish new stable interactions. Oleic acid is slightly polar but has a very long hydrocarbon chain that prevents water solubility.

c) The chemical bonds in silica are very strong so the particles cannot be further stabilised by dissolving in any solvent……(PS I hate this answer , will get back to you with a better one……)

d) Ethanol’s solvent properties are often intermediate between water and kerosene. It is a polar solvent, but not as polar as water. It can form hydrogen bonds with some solutes, but not as strongly as water. It’s small hydrocarbon chain allows a little paraffin and oleic acid to dissolve, but the solubility is low. Glycerine, however, is a small chain that has many OH groups that can form hydrogen bonds with ethanol.

8a) less soluble

b) 1.0 g

c) Carbon dioxide dissolves slightly as its electronegative oxygen atoms are attracted to the electropositive hydrogen atoms in water. As the temperature rises, the water molecules mopve more rapidly these intermolecular forces are broken so less carbon dioxide can remain dissolved.

9. It will form hydrogen bonds with water but only dispersion interactions are possible with non-polar kerosene. Therefore, this substance is very soluble in water but insoluble or sparingly soluble in kerosene.

10. The polar COOH group forms hydrogen bonds with water molecules. The non-polar chain is insoluble in water (as it cannot for significant intermolecular atttractions) so it floats on the surface with the COOH group dissolved in the water.

 

Question one……. Friday, Aug 10 2007 

HSC style Q's davisdag 5:24 am

Outline two properties for separating mixtures of solids and two for separating mixtures of liquids. What properties must the components of the mixtures have for these techniques to work?  6 marks

 Note – outline………sketch in general terms; indicate the main features of……

This one is valid until next Wednesday……good luck!!!

 

Some HSC style exam questions……. Friday, Aug 10 2007 

HSC style Q's davisdag 2:43 am

It is about time that we all start approaching questions in a mature and HSC orientated mode……..soooooo I thought I might add some questions and encourage you to respond via my e-mail……

In turn, I will send you a critique of your response and deliver you with a sample answer (one person’s version of what they think is right 🙂 ) . This process is trying to help you prepare for your HSC………make use of the support documents that exist in the back of your syllabus document and look very carefully at the verb used in the beginning of the question. This is the key to taking a coorect approach when formulating a response to a 3 (or more!) mark question,………It is a way to get the most marks from each opportunity……

 OK – to encourage you, each response that drops into my inbox will earn you one merit.

I will post questions twice weekly , from any area we have covered. The usual times will be once over the weekend and then again each mid week. I will accept responses up until the next question is posted.

I will post tips and hints etc and am looking for and encouraging you, to help yourselves here…..think that the few minutes you spend doing these will be ‘valuable’ and helpful as well as being time efficient, with feedback!!!!!!

 Look up later…….question will be posted………..