exam /study tip # 18 - ??VCE Exam Advice – Units 3 and 4 Chemistry Examination preparation is a two-step process. Step 1: Ongoing examination preparation. A thorough knowledge of the course work is required before you

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  • VCE Exam Advice Units 3 and 4 Chemistry Examination preparation is a two-step process. Step 1: Ongoing examination preparation. A thorough knowledge of the course work is required before you attempt practice examinations. This involves understanding core concepts and the memorisation of some areas of the course. This part of your examination preparation should be an ongoing process throughout the year. Making the mistake of doing this in the weeks prior to your examination severely limits the time you have to practice examination style questions. Chapter summaries are a good way to start revising. Also going back over text questions helps keep the various topics

    current in your mind. The more questions you complete in this subject the faster you will be in an examination and the better your result.

    You must be able to correctly define terms/concepts as specified in the Study Design. Learn these and practice them when writing practical reports or undertaking revision.

    Rote learn the necessary sections of the course e.g. solubility rules; nomenclature rules, catalysts and conditions needed for

    organic chemistry reactions.

    Familiarise yourself with the information provided in the Data Booklet which is incorporated into each VCAA Chemistry examination paper. If you do come across something in the examination that seems incomplete or requires additional information you will most likely find what is missing in this Data Booklet.

    Always use the calculator that you are going to use in the examination during class time.

    You can practice on the appropriate sections of practice examinations throughout the year but make sure you leave 2 VCAA

    papers until closer to the examination.

    Step 2: Practice examinations. While completing questions from textbooks can help you consolidate core concepts, they are rarely complex enough to prepare you thoroughly for the types of questions you will receive in the examination. Therefore, it is essential that you devote a substantial amount of time to practicing multiple choice and short answer questions from examination papers. This will highlight

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    exam /study tip # 18

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    your strengths and weaknesses and allow you to gain an understanding of how quickly you need to work in order to finish the examination in the allotted time. It will also be a good indicator of the depth to which you need to understand the course. As you complete each practice paper, annotate your notes with any extra content or additional detail that can be obtained from the solutions. In some short answer questions there are key words or phrases that the examiners look for so be sure to take careful note of this. An example schedule for completing practice examinations:

    1 month prior to the exam

    By this stage you should have a good grasp of most of the course content. Make sure that you have completed re-writing notes or chapter summaries by this point. Start practicing examination papers but do not be too concerned about how long they are taking you to complete. At this stage you may only complete some sections of the paper depending on whether or not you have finished learning the course work at school. Use the extra information found in the solutions to improve the depth and accuracy of your notes. If there are particular sections that you have difficulty with, spend some time relearning this section of the course. Try to complete 2-3 papers in this week.

    Three weeks out

    Continue using practice examination papers but start trying to complete whole examination papers and take note of the time they are taking you. Continue to annotate your notes with any extra information you find. Try to complete 2-3 papers in this week.

    Two weeks out

    By this stage you should have a very thorough grasp of the course content and be getting used to examination style questions. In this week, concentrate on completing the papers in the allotted time. Start doing past VCAA examination papers which are available on line. Keep in mind the course changed slightly in 2008 and 2013. Complete 2-3 papers in this week.

    One week out

    The most recent VCAA examinations will give you the best indication of what to expect in your examination. At a minimum, complete the 2012 and 2011 examinations using the allotted time.

    Generally, the more practice papers you can do the better. However, completing copious amounts of papers without absorbing new information or examination tricks will lead to burn out. You need to take a balanced approach to your study which can best be done by being organised and not leaving it until the last minute. Many students struggle to complete the examination within the allocated time so excellent exam technique is critical in this subject. Strategies to maximise examination scores are being addressed in our free Mastering the Exams lectures, as well as during the course of the Essentials Final Exam Revision Lectures that are being held during the Term 3 school holidays. You should also read through the previous Assessment Reports that have been written by the Chief Assessors so that you can secure the best possible examination scores. These reports include valuable information regarding how to set out answers, key phrases and words that are expected in short answer responses as well as common errors made by students. Students should work through at least 15 examination papers if they are aiming for the higher scores. Remember that new Study Designs were implemented in 2008 and 2013, so not all the questions from past papers are relevant to the new Study Design. PTO

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    Major changes made to the Study Design in 2013 include: Unit 3

    In Unit 3, students are no longer required to learn the features of instrumentation and operation of chromatography and

    spectroscopy techniques so disregard these questions in practice papers

    Reaction mechanisms and rate laws are now a part of collision theory and rates of reaction. Unit 4

    In Unit 4, students will investigate the production of one industrial chemical selected from ammonia, sulfuric acid or nitric

    acid. This will be assessed through School-assessed Coursework only. Therefore, disregard these questions in practice papers as well as any on ethene (which used to be one of the chemicals studied).

    Petroleum has been included as one of the energy sources to be studied.

    Although many other changes were made, they were mainly clarifications of the course and expanded explanations of the dot points from the previous Study Design. More details on the changes made in 2013 can be found at the following website. http://www.vcaa.vic.edu.au/Documents/bulletin/2012/2012julsup.pdf Also remember that this is the first year in which students will be assessed via one paper at the end of the year. This means that concepts from Unit 3 and 4 may be linked together in ways that were not possible in previous years (e.g. an equilibrium reaction could be monitored using some type of spectroscopy). Every opportunity should be taken to do these types of questions so look out for them in practice papers. You can find details of the new format and a practice examination on the VCAA website: http://www.vcaa.vic.edu.au/Documents/vce/chemistry/Chemistryexamsample.pdf Those students who plan to attend The Essentials final examination revision lectures will further benefit from exposure to hundreds of additional potential examination questions, most of which are unique questions designed to expose students to the finer details of the Chemistry course, as well as the possible tricks, traps and extended applications that students could be presented in the examinations.

    General Comments Regarding the Unit 3 & 4 Chemistry Examinations 2012:

    Table 1: Distribution of Unit 3 Examination Scores

    A+ A B+ B C+ C

    Ideal Paper 90% 80% 70% 60% 50% 40%

    2012 90% 83.3% 76% 67.3% 56.7% 47.3%

    2011 85.4% 79.2% 72.9% 65.3% 54.9% 45.1%

    2010 89.3% 82% 74.7% 66% 56% 46%

    2009 78% 69% 60% 51% 41.8% 32.2%

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    These results suggest that the 2012 Unit 3 examination incorporated sufficient numbers of difficult questions to seed out the A and A+ students, but was otherwise too easy, which is why so many C to B+ students felt they had performed so well in the actual examination. Therefore, it would be expected that the hardest questions in this section of the course will not be any harder than the questions found in 2012 but overall, the difficulty of the paper may be increased this year.

    Table 1: Distribution of Unit 4 Examination Scores

    A+ A B+ B C+ C

    Ideal Paper 90% 80% 70% 60% 50% 40%

    2012 84% 78% 71% 63% 52% 42%

    2011 87% 79% 71% 61% 50% 40%

    2010 88% 82% 74% 65% 54% 43%

    2009 88% 80% 71% 61% 51% 40%

    These results suggest that the 2012 Unit 4 examination incorporated a number of difficult questions that lowered the percentage needed to obtain an A+, but was otherwise pitched at about the right standard. Therefore, it would be expected that the questions used to seed out the A+ and A student may be a little easier than last year but the overall difficulty of this section of the paper may be about the same. Statistics can be found at: http://www.vcaa.vic.edu.au/Documents/statistics/2012/section3/vce_chemistry_ga12.pdf Problem Areas in the 2012 Examinations: The Unit 3 examination was generally well done. Some students struggled with identifying monomers and linkages in a polymer, drawing the structure of a polymer, doing stoichiometric manipulations, writing accurate equations and identifying a back titration. Therefore, these are areas that the examiners may focus on again in order to encourage a better understanding of these sections. The main problem encountered in the Unit 4 examination was applying knowledge to new contexts. Basic application and identification of facts was addressed well, but many students missed out on marks as they were not familiar with the finer points in Chemistry Students should keep in mind that well-learned responses are sometimes inaccurate in the context given. Dealing with such applications does require exposure to specific questions and materials (rather than standard questions from text books), and our teachers involved in the Unit 3 Exam Revision Lectures have spent considerable time compiling unique and targeted questions so as to give students the greatest possible edge in the forthcoming examination.

    Things to Watch Out For

    Unit 3: Chemical Pathways Volumetric and Gravimetric Analysis Examiners are good at finding new errors for you to analyse. Make sure you are competent at determining the effect of

    errors on volumetric and gravimetric procedures. Remember that the effect of the error may change depending on whether the unknown solution is in the burette or in the flask under the burette.

    Learning the solubility rules is a MUST. PTO

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    Chromatography:

    Ensure that you are familiar with both normal and reverse phase chromatography.

    The role of the mobile phase in GLC is to act as a carrier gas. All gases are miscible with the carrier gas, so separation is not based on the relative affinities of sample components and the 2 phases. Separation is solely based on the strength of the interparticle bonding formed between sample components and the stationary phase.

    The solvent used in GLC is not the mobile phase. The solvent is the liquid that is used to dissolve the sample, which is then injected to the GLC and vapourised. The solvent may therefore produce a peak in the spectrum.

    Area of study 2: Organic Chemical Pathways: The hydroxyl group is OH not OH (this is called the hydroxide ion eg. as in NaOH ).

    The carbonyl group is a family of functional groups containing C O . As an example, ketones, aldehydes etc. The C O

    by itself is not a functional group. Therefore, the functional group in carboxylic acids is the carboxyl group (COOH ) and not the hydroxyl and carbonyl groups. The only time you can treat the carboxyl group as being made up of two functional groups (C O and OH is in infra-red spectroscopy.

    When stating systematic names of organic compounds, students must apply the IUPAC system and ignore what has been

    accepted in previous Assessment Reports. Students must also be aware of the order of priority of the principle functional groups, something that is not addressed in most VCE textbooks.

    Learn combustion, fermentation and respiration reactions involving glucose.

    Unit 4: Chemistry at Work Area of Study 1: Industrial Chemistry Practice writing concise and accurate answers on rates and equilibrium. There are often key phrases and words that the

    examiners are looking for in this section.

    pH is an area of the course that is often poorly handled. Make sure that you can find the pH of mixtures of acids, mixtures of acids and bases and solutions that have been diluted. The pH of weak acids is also often poorly handled. You should review this section thoroughly.

    Area of Study 2: Supplying and Using Energy The Electrochemical Series is almost always written as reduction half equations. If necessary, to answer a redox question, put

    equations in order of strongest oxidant on the top left and strongest reductant on the bottom right. The predominant redox reaction occurs between the strongest oxidant and the strongest reductant, which in this case would be the highest species on the left and the lowest species on the right.

    Include all redox half equations that involve water when dealing with an aqueous solution.

    When using the electrochemical series dont assume 2O is present unless actually stated. PTO

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    When writing overall redox equations, remember to balance the number of electrons in the oxidation and reduction equations before adding the half equations together.

    Practice writing overall equations from two half equation and also be able to deduce the missing half equation from the

    overall equation and one of the half equations.

    During the Examination

    If a theory question is worth two marks then be sure that you have clearly made two distinct points, particularly if it is asking for an explanation.

    Never ever move onto a new question in any subject without reading the question that you have just completed. Many students miss out on valuable marks as they did not provide the required answer.

    If you do come across a question that looks similar to what has appeared in previous examinations, proceed with caution.

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