* you need to identify a biopolymer

* identify some potential uses / uses of the biolpolymer (note, for 6 marks you would expect more than one here….)

* evaluate the uses …….. so this means to make judgement statements (that you have qualified) for each use…..

Well done Ben, Preethi and Josh….keep it up….you all were vey close to a 6….no, Preethi, you don’t need advantages and disadvantages for evaluate questions.

Question Three

Outline a procedure for determining the heat of combustion of an alkanol and justify the procedure you used.   6 Marks

* Describe a procedure for making the 1L solution with a 1 in 5 dilution that included placing acid into the water with the addition of stirring.

* Describe the safety procedures necessary such as, performing the procedue near a water supply, wearing safety equipment (chemically resistant gloves, safety goggles  and lab coat)

*Outline the reason for the precaution – exothermic nature of the ionisation of sulphuric acid and the fact that sulphuic acid is a stong acid.

How did you do……maybe go back and eview your responses…..

Question TWO

Evaluate the use or potential use of a specifically named biopolymer.  6 marks

Good luck, looking forward to reading your answers

1. Briefly describe how you would dilute concentrated sulfuric acid to make a 1L solution consisting of 1 part acid to 5 parts water. This solution is to be used in reagent bottles. State the safety procedures you would need to consider.

This question could be worth about 5 marks……is not a HSC question, but certainly one you will need to be able to respond to. Please provide feedback for other students about their answers. Making guidelines for a 5 mark response will be up on Sunday……looking forwad to seeing your answers.

See you all then…………  

Oh, and my plan this year is to get challenges up here all the time…..might even fit one in on Tuesday for you………

Good luck Year 12………{bowing my hat to you all}…………but NEVER goodbye LOL!!!

This is not a HSC question , but will be worthwhile anyway.

1. A student undertook a series of dilutions of 0.010 mol/L of nitric acid (solution A). A 10.0mL sample of solution A was measured out and transferred to a 100mL volumetric flask. The flask was filled to the mark with distilled water, stoppered and thoroughly mixed (solution B). The procedure was repeated with 10.0mL of solution B which was diluted accurately with distilled water to produce 100mL of solution C.

a) Name the piece of glassware used to measure out the 10.0mL of the acid.

b) Calculate the pH of solution C.

c) what is the minimum concentration of H+(aq) that the student can obtain through such successive dilutions? Explain

d) Propose a method for preparing a solution with an [H+] of 1.0 x 10 -10 mol/L

This was a five marker…………………maybe a little off track – see how you go

Oxides can be classified as neutral, acidic, basic or amphoteric. Carbon monoxide is a neutral oxide.

a) Sulfur dioxide is an atmospheric pollutant which leads to acid rain. Use a balanced equation to explain how sulfur dioxide is classified as an acidic oxide.

b) Write a chemical formula for an oxide that is strongly basic.

c) Lead(II)oxide is an amphoteric oxide. Use balanced equations to show why lead(II)oxide is amphoteric.

This would have been a three marker….. this is on track – so make sure you can do this!!

3. 20.0mL of dilute sulfuric acid were placed in a flask and 3.00g of barium hydroxide added. The solution was stirred until reaction was complete.

a) Write a balanced equation for the reaction

b) Name the precipitate formed in this reaction

The excess barium hydroxide was back titrated with 0.100mol/L hydrochloric acid. 34.5mL of hydrochkloric acid were required for exact neutralisation.

c) Write a balanced equation for the back titration reaction

d) What indicator(s) would be suitable for this titration?

e) Calculate the concentration of the original sulfuric acid solution.

This would also be a 5+ marker.

Have a go and see how you go.

So how are you all going?? Everyone coping ok???? You have been verrrryyyyy quiet!!

1. During your practical work you performed a first hand investigation to identify the products of electrolysis of sodium chloride.

(i) Outline a risk assessment for this investigation, and show how this would influence the experimental procedure. (3 marks)

For 3 marks you will need to outline TWO specific hazards for this first hand investigation AND provides a specific method for control of each hazard

(ii) Provide a conclusion based on one set of observations from your first hand investigation. (2 marks)

For 2 marks you will need to provide ONE set of observations and a conclusion based on that set of observations for the first hand investigation.

2. Atomic absorption spectroscopy was used to analyse a set of standard solutions of copper. The results are presented below

Concentration of copper (ppm)         Absorbance

0                                                          0

5                                                          0.2

10                                                        0.39

15                                                        0.52

20                                                        0.64

25                                                        0.77

a) Draw an appropriate graph of the data (2 marks)

For two marks will plot points correctly and draw a curve of best fit through the points.

b) An analysis of two samples containing copper was then performed. the results are given in the table .

Sample   Absorbance

1                 0.44

2                 0.90

Use your graph to estimate the concentration of coppeer present in the samples, and assess the validity of each of your estimates. (3 marks)

For three marks you will need to

* provides an accurate assessment for both samples based on the  graph

* Priovides a judgement for both estimates

* provides a reason for both judgements.

Good luck guys……..

1. Draw a segment of the polymer , polyethene and outline the steps in it’s production . (2 mark EASY PEASY one)

2. The following equation shows the equilibrium that exists between gaseous and dissolved carbon dioxide.

CO2 (g)  ↔ CO2(aq) + heat

Explain , in terms of LeChatelier’s Principle what happens to the solubility of carbon dioxide in the ocieans as the temperature increases (going from winter to summer). (2 mark, need to think question)

3. Explain the need to monitor levels of lead and phosphate in our waterways . (4 marks……hmmmmm)

Hope that keeps you all off the streets and busy studying…………… will return with more – I promise!!!!

The flow chart shows a series of steps involved in the production of ethyl benzoate

Glucose …………mixture containing ethanol…….pure ethanol……..ethyl butanoate

Describe the chemistry and procedure involved in each of these steps, using diagrams where appropriate…

7 MARKS………don’t worry about trying to show me diagrams etc….although you can e-mail this if you like….