Saturday afternoon - Quizzes defeated (on right). Ready to to tackle the assessment mountain (on left, I've named it Gregor).
The trouble with small mark quizzes and 'no half-marks' means that each little mistake is penalised with a full mark loss AND that equates to every little mistake deducting approximately 3%. It is vital to remove any errors from your answers (even more important than exam technique).
That being said - everyone passed with marks to spare.
You are all improving
You are all on the road to awesome
BUT YOU ARE NOT THERE YET!
This made me LOL while I was procrastinating WARNINGMay contain Game of Thrones Spoilers
Monday - Midnight
Since the last update I have managed to mark 1/4 of one persons assessment. I have retreated to the couch to reconsider my strategy of attack. Gregor is a far more fearsome opponent than I imagined.
Late Tuesday / Early Wednesday
ARRRGGHHHH
Gregor is a beast!
So far Stage 1 is finished - 1/4 of every students questions have been marked.
But because of some silly marking criteria design I have to go through every question and assign them outcomes H6-H9 (and also adjust some student-assigned H3-H5) before the marking can continue onto stage 2.
Late Wednesday / Early Thursday
They say the pen is mightier than the sword. But not my pen - Gregor will just not die. It is taking all my willpower not to succumb to the voices in my head "Kill it with fire, kill it with fire..."
And while this may be amusing to you it was not so great for me when I realised that what I thought was 1/4 finished was actually 1/8th finished. ..
Nevertheless, I am now 1/4 through, I've developed a system and am on a roll.
In case you didn't see, the Game of Thrones Season 3 Trailer was released a few days ago. It contains MAJOR spoilers for those who haven't seen season 1 and 2. You have been warned
Late Thursday / Early Friday
Half way
Late Friday / Early Saturday - ALMOST DONE
Another fruitcake, five coffees, a midnight curry and half a box of Lindt and it is done. Gregor is defeated. Now only about 5 hours of spreadsheet data-crunching and feedback-making and I can be rid of this monstrosity.
Late Saturday Night
Hmmm...10 hours of data entry later and I've got the marks into Excel. I hadn't considered the fact that because all your questions were different and because all your topic, skill, H3, H4, H5 etc questions were in different places I couldn't just simply copy & paste and drag formulae around. No. Instead I had to create a new data table and a new set of calculations for each persons set of questions.
Below is the Column A to BU, Row 1 - 186 behemoth that was the bane of my post-'Open Day' Saturday.
A lot of misconceptions and ugly Chemistry appeared in this set of activities. Most can be squashed pretty easily – but it is going to mean that you have to do some practise to get incorrect habits/thoughts out of your minds – if you made the same mistake 20 times in this activity it is going to take about that many correct attempts to purge your brain of that incorrect approach. You want to make sure that your exam-subconscious-autopilot-brain mode has the correct instructions hardwired in or else…
But before I look at the most troublesome questions here is myRant of the Week
1)Electrode potentials MUST include the unit VOLTS. Without Volts (or at least a capital V) the answer is meaningless. Don’t let all that hard work calculating the answer be worth nought because you forgot to add a V at the end of your answer.
2)Cu2+ and Cu+ are NOT the same thing. Use the correct cell potential!
Cu2+ + 2e-® Cu (s)Eo = 0.34V
Cu+ + e-® Cu (s)Eo = 0.52V
If you are ever doing a copper cell then it is mostly likely to be a 2+ solution and the reduction potential is 0.34V. Learn to love that number and learn to be wary of 0.52V.
3)We learn these things for a reason: OIL RIG, RED CAT, ANGRY OX, ABC’s. At the very least check what you have written against these rules. e.g. you have written a half equation where electrons are being lost then (OIL RIG) that means it is oxidation and (ANGRY OX) that means it is at the anode which is –ve.
4)USE THE REDUCTION POTENTIAL SHEET!. E.g., If you are told that there is a chlorine half cell then look at the data sheet to, not just figure out ABC’s but to also to figure out what reactions are possible. All of these examples below are wrong for many reasons, but that didn’t seem to stop anyone – you should be able to explain what is wrong with each one of these:
Cl2® Cl- + e-FAIL
½Cl2® Cl2 + e-WT FAIL
Cl- + e-® Cl2SO FAIL
Cl- + e-® Cl+SO VERY FAIL
Cl+ + e-® ½ Cl2FAIL
½ Cl2 + e-® Cl+EPIC FAIL
½ Cl2® Cl+ + e-FAIL
Q1) The dry cell is also known as the Leclanche cell (after the inventor of one of the first dry cell batteries). It is non rechargeable. The Lead acid battery used in cars IS rechargeable
Q2) Just do it – people must have thought this was part of Q3 as many skipped it (and it was easy)
Q4) When converting from half equations to a full cell equation you must make the electrons balance before you add the half equations together. But when converting a full equation into half equations you should simplify the half cell equations at the end.
Q5,6, 7, 8) Main issue is reading the question and doing all the things the question asked.
Q6) So very bad – see Rant point #4 above. Also in shorthand notation it should go: ion|related gas,Pt
E.g. ||Cl- (aq)|Cl2(g),Pt
Q9) All pretty good except the overall cell equations. Just like any galvanic cell overall equation you: a) make the # of electrons the same in both half equations (i.e. for the dry cell you need to double that whole monkey-nuts equation)
b) simplify at the end (i.e. for the silver cell, the fact that electrolyte concentration stays the same means you should be able to cancel out the OH and H2O on both sides)
Q10) Just be careful - ‘ decreasing tendency’ means gong from the most likely to least likely
Q11) Similar to rant point 2 above. You need to be aware that there is a Fe2+/Fe half equation and a Fe2+/Fe3+ equations. Read the question carefully to know which one you need to use
Q13) To prove a reaction occurs ’as written’ means you need to prove the reaction is spontaneous. Spontaneous redox reactions give a positive Eo value. If you look at the equation provided, one reaction taking place is the oxidation of Iron(II) ions: Fe2+® Fe3+ + e-. Take out the Fe2+ and Fe3+ terms from the equation and you are left with the other half equation. That is on the data sheet too. Just add the Fe2+ oxidation Eo to the Eo of the reduction process and see if it is spontaneous.
Q14) First - figure out which is oxidised and which is reduced from the equation, then just add the two potentials together (remembering to reverse the sign of the oxidation Eo)
Compulsory activities – need to be done. What was done was done well except for-
Q2i) Draw the cell diagram needed to measure the Ti|Ti2+ cell potential. To measure a standard cell potential you need to connect it to the standard reference electrode. This is in your notes - you need to look up what the standard electrode is AND its conditions. Yes, technically you can figure out the Ti-cell potential by connecting it to Mg or Ni etc etc as some people drew– but you need to be able to explain the use (and draw a picture of) the standard reference electrode.
Summary feedback
A)We didn’t sand lead, we used a multimeter set to read voltage (not a voltmeter) & we used a new salt bridge for each new galvanic cell.
B)Explain means give a reason – so in the Chemistry context, that means give a reason based on some Chemistry concept. E.g. it is not good enough to say ‘The cell needed a salt bridge’. You need to say ‘The cell needed a salt bridge because...’ where you go on to give a reason based on chemistry.
C)While it is true that the greater difference in standard reduction potential, the greater the voltage (and you should say this) the Q refers you to the activity series so you should also relate the voltage to the relative reactivity of electrodes. Basically, the bigger difference in reactivity, the greater the difference in reduction potential and thus the greater the cell voltage.
D)Standard conditions are 25oC and 1mol/L solutions (and gases at 100kPa). If these conditions are not met the Eo values for the cells will be different to the data sheet and thus the cell potential (and possibly anode and cathode as different cells are effected differently by changing conditions) will be different to that predicted by the sheet. Corrosion or damage to the electrode surface can also change the transport of ions to the surface and effect Eo values.
E)You must mention storage (for proper disposal) all heavy metal solutions as part of your safety (i.e. do not tip down the sink)
F)Beware of the Cu+ vs Cu2+ problem identified above
G)Extracting data from graphs and tables is not just vital to extract data from standard potential tables to assess the validity of our experiment, it is also vital as that is how most numerical data is reported and scientists need to use this data to make calculations, judgements, conclusions and generalisations (i.e. about tends and patterns).
H)You need to calculate the theoretical voltages for your table, but take care with cell voltages to use the correct values. Also, the theoretical value should always be positive (i.e. the theoretical value is the voltage for the spontaneous reaction that should occur. Spontaneous reactions happen automatically without net energy input so their Eo will always be positive).
I)If you are gong to say ‘the salt bridge completes the circuit’ make sure you follow up with ‘by maintaining charge neutrality in the half cells’.
J)KISS – Keep it simple students. Answer the question and don’t over explain. Some of the explanations we use in class are gross-oversimplifications of very complex processes. I use these so that you get a better understanding of the basic process (so you will more easily comprehend & remember the theory) – but they aren’t so good in written reports. Eg for Q3c – just say ‘Anions migrate to the …. through the …. while cations….
K)In your results table, at minimum, you must include all the cells asterisked on the Excel table of result. Cu/Zn, Cu/Fe, Zn/Al, Al/Ni, Ni/Mg, Mg/Pb, Pb/Fe
L)Your cell diagram needs to have the full cell reaction, both half cell reactions, salt bridge, flow of electrons and ions labelled, +, -, all chemical species labelled AND label the anolyte and catholyte.
While I was marking the Experiment summaries I was imagining what an awesome game it would be if they made a Game of Thrones version of Kingdom Rush (a similar concept to the 'Rio' version of 'Angry Birds' but bout a trillion times cooler).
I then had to have a soundtrack for my marking - cue the Youtube hits below. Some people are very talented and have too much time on their hands.
If this does not send shiver down your spine then you need to a) stop what ever it is you are doing b) read 'A Game of Thrones' and/or c) Watch season 1 of the TV series d) come back here and watch this clip again to feel that sense of the awesome that sends a shiver down your spine
And to think that when I was younger I used to think that playing the violin was uncool. I was so naive in 2012
Hmmm, despite the fact that this performer has more talent than I can possibly imagine and despite the awesome choice of music, I'm still not convinced that the flute is cool - but seriously are these things even flutes?...
While the Piano Guys have the definitive Harry Potter and Pirates of the Caribbean performance, I'm still searching for the ultimate Piano of Thrones. This is one of the best I've heard so far
These next two blew me away. I wish I was cool enough to play a guitar.
I admire cellists ability to persevere with their instrument even while knowing that nothing played on a cello will ever surpass Cello Wars.
Well, these two instruments aren't really to my taste but it takes all kinds...
And the award for the most creepily awkward performance goes to...
And now to some Game of Thrones songs for your next birthday party, bucks or hens night or wedding
And then to the most coldest black-hearted song ever
And if you have seen the TV series you will probably find this funny (I did). If you haven't watched it- well, this clip won't make any sense and you will spoil the ending of season 1.
Actually I removed this because I thought about the content and then thought about who the audience is.
If you are determined to see it look up (and watch in this order, noting that they are major spoilers)
Hitler and Ned
Hitler and Khal Drogo
Hitler and Blackwater
The last one - even the name Hitler and... might be a spoiler
I did some testing after class and discovered that beakers 5-7 and 9-10 were a bit mixed up
Real pH (labelled pH)
0.9 (1)
2.1 (2)
3.4 (3)
4.2 (4)
4.6 (7)
5.4 (5)
6.7 (6)
7.8 (8)
10 (10)
12.1 (9)
So I re-ordered the test tubes to show lowest to highest pH and re-took the photos - shown below.
HINT - When assessing a natural indicator you have to ask - does it have distinct colour changes at certain pH's? Does the one colour give a consistent pH (or consecutive range of pH's)? Are the colours easy to interpret?
Generally good responses but a disappointing amount of errors relating to oxidation #’s, oxidation and reduction.
Q1f) For positive metal ions the oxidation state is always equal to the charge on the ion. Such ions can range from +1 (eg Na+) to +8 (eg Mn8+).
Q3b) For any redox reaction the atoms and the charge must balance
Eg Ag+(aq) + Pb (s) → Ag (s) + Pb2+ (aq) – the atoms are balanced but the charge is not (+1 in the
reactants and +2 in the products)
If you think about the half equations for this reaction
Ag+(aq) + e-→ Ag (s)
Pb (s) → Pb2+ (aq) ++ 2e-
It is clear that 2 silver reductions are needed for every lead oxidation, so the balanced equation is
2Ag+(aq) + Pb (s) → 2Ag (s) + Pb2+ (aq) – now atoms and charge are balanced
Q5) writing ionic equations means that there should be no spectator ions. For 5c) according to metal displacement only the most unreactive metal ions will be reduced and form a solid. All other metal ions will end up in solution. Even still, do not include spectator ions in your equation
Q7) People who drew the grid typically got this correct. If you didn't and you got it wrong – DRAW THE GRID. If you did draw the grid and got it wrong it was typically because you i) didn't complete the grid for all species or ii) forgot what oxidation and reduction mean.
If the oxidation # increases it has been oxidised (ie, it is the reductant).
Eg if lead goes from 2+ to 4+, because 4>2 it has been oxidised.
Eg If chlorine goes from -3 to -1, because -1>-3 it has been oxidised (don’t forget the basics of the number line!)
If the oxidation number decreases (ie reduces) it has been reduced (ie, it is the oxidant).
Eg if manganese goes from +3 to +2, because +2 < +3 it has been reduced.
Eg If sulfur goes from +3 to -2, because -2 < +3 it has been reduced
AMAZING NEWS – Kingdom Rush 2 is coming out in Autumn!!!!!!! I AM SOOOO EXCITED!
SUMMARY FEEDBACK
Summaries were very good, just a few errors kept appearing.
A)Remember that we had to clean the electrodes between each different solution tested & at the end we tested the solution that gave a reading with two Cu electrodes and then two Zn electrodes.
B)You need to put the units for all measurements in the title-row of tables and you need to use units when referring to quantities in your text.
C)This experiment was about the BASIC requirements of a galvanic cell. Thee are only three things needed (four if you count each electrode separately). Even though the cells we analyse in problems have two different electrolytes and a salt bridge that is not really necessary (just easy to mathematically analyse). Also - remember that the electrolyte AND conducting path need to connect both electrodes.
D)Two different metals are needed so they have different reactivity. One tends to be oxidised more (it is a stronger reductant) than the other. This means there will be a potential (voltage) established between them that will allow current to flow when connected in a galvanic circuit.
E)You must mention that the flow of ions in the salt bridge maintains charge neutrality and allows the current to keep flowing (“completes the circuit” is OK but not sufficient).
F)Keep a) and b) simple – one is oxidation, one is reduction… For c) you have to think carefully
This is the galvanic cell we set up in the experiment
i.e. a zinc and copper electrode, separated by a salt bridge with an electrical contact (I’m going to refer to it as the experiment cell).
This is SIMILAR to the galvanic cell below.
Zinc is the anode because it is more reactive, copper the cathode, zinc gets oxidised at the anode (ie Zn ® Zn2+ + 2e-) & copper ions get reduced at the cathode (Cu2+ + 2e-® Cu)
It is easy to assume that this is exactly what happens in our experiment cell, BUT -
While the Zinc in the experiment cell can be oxidised (so the anode reaction is the same) we have a problem at the cathode. This is because we have no copper ions in our experiment cell. So there must be some other cathode (reduction) reaction occurring.
This is where we have to ask yourself: “What else could be being reduced if not copper ions…?”
We do know that we have water in our salt bridge AND because it is exposed to air there will be a small amount of dissolved oxygen in the salt bridge too.
Hmmm…
Perhaps there is a reduction equation on the reduction potential list that has oxygen and water as the reactants in the reduction equation…
G)The results table needed a simple summary e.g. “The only cell that gave a reading ….”
H)You need to say that the more reactive metal (has a lower reduction potential &) will be oxidised, thus act as the anode which by definition has negative polarity. The less reactive metal will be the site of reduction…. Don’t forget to always apply OIL RIG, RED CAT and ANGRY OX to remember you polarities, sites of oxidation/reduction and which electrode gains/loses electrons.
I)I can no longer remember what the ‘I’ was supposed to indicate…If you figure it out please let me know.
J)Always be specific, don’t just say electrons (or ions) flow between electrodes, say exactly where they come from and go to (just like we never say ‘colour changed’ we say exactly what colour changed to what other colour).
K)The multimeter advantages are very simple. They relate to accuracy, ease of use and reduction in human error – just think to when you used the multimeter - what made it better than trying to use a voltmeter?
L)Don’t forget that you need to include your original hypothesis.
Luckily, Orcs Must Die
is giving me my fix of tower defence (albeit first-person tower defence) until the sequel to the greatest game of all time, Kingdom Rush, is released (seriously, click the image below to play it. Play it NOW!)
This set of questions was a perfect example of why it is so important to be thorough with your Chemistry. Most people for most extended response questions lost a mark for a small error or because thye didn’t use an important Chemistry term in their answer. As a one off it does not really matter but across the whole paper it counts for approximately 25% of the available marks.
But generally the answers were very good and you should feel proud that you have completed so many HSC questions this early in the course. There are many students who wont even start doing this sort of work until stuvac. We have a whole 6 months to clarify any misconceptions, reinforce the depth of out understanding and fine-tune our exam technique.
Specific feeback
2001
Q27) This was a tricky question to navigate because the source was unusual. It was a diagamatic graph. But because it was a graph it contained data and that measn you need to specifically refer to it. Eg “Ozone is mostly found in the stratosphere (up to 4.7ppm), while it is a maximum of 0.9ppm in the troposphere”. You then needed to describe its effects ‘nearby’ and ‘ip high’, which we did well BUT you need to sue the correct terms. Don’t call it the lower atmosphere- call it the troposphere. Don’t say the ozone is in the upper atmosphere – say the stratosphere.
2002
Q25) b) This should have been an easy two marks but you need to be able to draw Lewis dot diagrams correctly (dots or lines – NOT both lines and dots for the bonds). You should always label the coordinate covalent bond.
Q25) c) Remember the dot next to the free radical. Also a phrase you need to work into ALL of your answers about CFC’s impacting ozone is “Cl free radicals catalyse ozone decomposition”.
2003
Q12) Because the graph showed the breakdown of one mole, you could just read off the graph C:F:Cl = 2:4:2 and remember wee don’t simplify covalent compounds (only ionic).
2004
Q12) We will cover this in the Acidic Environment topic
Q27) Answered really well but you need to refer to the data in the table. You need to describe CFC’s impacts (another opportunity to write: “Cl free radicals catalyse ozone decomposition”), refer to HCFC and HFC’s. You need to say the + and – of each and assess. which is most suitable. Also – 7 marks is a LOT – you MUST use chemical equations in all answers >3 marks
2006)
Q5) These isomer Q can be tricky – but I just draw myself some diagrams and eliminate the impossible multiple choice answers as I go.
Q28) The image shows a global analysis of ozone – thus they must have used a satellite system. BUT- you MUST know that TOMS is not longer being used. They are using the OMPS (Ozone mapper profiler suite) on the AURA NPP Satellite. Finally –when it says discuss the ozone hole over Antarctica you must mention general depletion by CFC’s and the ozone hole that forms in Spring. But also NB that there have been some recent signs that the annual hole-size is not getting bigger.
2007
Q15) – I’ve said it enough times above ‘“Cl free radicals catalyse ozone decomposition”…
Q16) b) Once again an extended response question greater than three marks – You must use at least one balanced chemical equation (Eg ozone absorbing UV)
2008)
Q18) b) Apart from drawing a correct diagram of both, the other key things are to:
i)Note that ozone is bent and has a dipole, thus it is more soluble in water than oxygen (like dissolves like)
ii)Ozone greater size means it takes greater energy to vibrate – thus higher mpt and bpt
iii)Note that the single bond in ozone is easier to break then the double bond in oxygen – thus it is more reactive
It is very important to note that it is NOT the polarity or the coordinate covalent bond that makes ozone reactive. Once formed the coordinate covalent bond acts as a regular covalent bond.
Q21) A lot of students skipped this but really – it would have ten 30 seconds to look up the BOS and download a copy. I also wrote a description of the graph in the ‘graph space’ to help you out.
2009) – 2010)
Q12 & Q4 on the topic of naming – please don’t forget all the tricky rules (include hyphens, 2 – di, 4 = buta etc)
I was impressed with your mathematical answers. The only
concern here was converting between heat per gram and heat per mole (molar heat
of combustion).
We have derived the equations for converting these in our notes
but you don’t need to derive them I your answers, you can just rely on this
equation:
Heat per mole = heat per gram x Molar mass
DcH = J/g
x M (and obviously this means J/g = DcH / M)
So the equations you need for heat of combustion are (and
you should know most of these without needing to ‘memorise’ them):
q = mCDT
J/g = q/mfuel
DcH = q/nfuel
nfuel = mfuel/Mfuel
DcH = J/g
x Mfuel
In the written responses the answers were generally thorough
and demonstrated a dee understanding. One major point is that in 9.2.3 we are
focussing on the ‘real’ world – ie humans ARE using glucose (from sugarcane) to
make ethanol. This is different from 9.2.2 where the focus was on the POTENTIAL
to convert cellulose into fuels (ethanol) and materials (ie via ethene) – ie
not something that humans are actually doing. So when it comes to discussing
ethanol you don’t need to start the process at cellulose (biomass) unless
specifically asked.
Tips for specific questions
2002
Q1) Anything above 36oC starts to harm the yeast
(its enzymes don’t function as efficiently)
2003
Q6) This is converting between J/g and DcH. However, you need to think:
Is it easier to convert all four J/g data values to DcH to find the right one OR just convert the single
DcH value to J/g to find the right one?...
2003
Q16) In this questions and ALL fermentation experiment
questions – the focus is on i) Did you specify the correct chemicals (glucose,
water, yeast) ii) was it an open container & iii) did you specify that you
measured the mass before AND after fermenting (ie to measure mass loss). You do
NOT need to go into detail about our airlock system UNLESS it asks about how
you prevented oxygen entering and proved CO2 was produced. All you
need to say (at the very most) is that “an airlock system was used to allow CO2
to escape but no air to enter”.
2004
Q25) Whenever you are given a graph (with numerical axes) or
a table with numerical data YOU MUST REFER SPECIFICALLY TO THE DATA (ie
numbers) in your answer. Eg “ethanol’s heat of combustion is 29.7 kJ/mol
compared to octane’s 47.9 kJ/mol…”
2005
Q20) You should be able to do from Glucose to pure ethanol
BUT do not start from cellulose (see notes above) – in addition the Q specified
for the process in the flow chart and there is no cellulose in the flow chart.
2006
Q2) You need to know that concentrated sulfuric acid is a
dehydrating agent (thus used for dehydration of ethanol into ethene). Dilute
sulfuric acid is used for hydrating ethene into ethanol (this was the whole
focus of our Experiment #3)
Q18) Just be careful to read the question and use your mole
ratios correctly – many students were mixing up and finding masses of ethanol
rather then glucose.
2007
Q24) a) If you are asked to plot a graph with molar mass or
molecular weight as the axid you have to calculate and plot it correctly.
Q24) b) When determining values from a graph you should mark
the value on your graph with lines to the axis.
2008
Q22) for this Q I would show the chemical reasons why
ethanol is theoretically CO2 neutral. But then discuss the reasons
why it does produce some net CO2, then I would MAKE A JUDGEMENT on
the article. If you do not put a judgement on an assess or evaluate question
you will lose 1-2 marks.
Q24) An excellent combination of moles J/g and DcH. I strongly recommend that you
do this question again if you made a mistake. Knowing how to answer this
question will greatly increase your understanding of these sort of
calculations.
2009
Q17) If you read the question carefully you will see that
you have to explain the similarities AND differences between water and ethanol
solubility. You need to draw a diagram of both with the polarity labelled. You
need to make a statement about like dissolves like. You need to state why both
can dissolve polar and hydrogen-bonded substances. But then you need to say why
ethanol can dissolve non-polar substances BUT WATER CANNOT – without this last
statement you have not explained the differences.
Q20) a) When heat is lost to the surroundings the questions
can be tricky. If calculating the heat of combustion this means that the heat
you measured will be half what is produced so you need to double the calculated
heat of combustion. But if calculating the amount of fuel that must be burned
you need to double the theoretical amount of
fuel as half the heat is being lost. This is a question to do again for
study.
Q20) b) A real sneaky question – most of the time the two
ERRORS are heat loss and incomplete combustion BUT this question wanted two
methods to reduce heat loss (only) – e insulate the container and move the
flame as close as possible to the container.
2010
Q11) To answer this question you had to think – what
chemical decolorises Br-water (alkene) & what chemical is dehydrated by
sulfuric acid to make an alkene (alkanol)…
Q23) b) A nasty question. Similar to 2003 Q6 – I would
convert the DcH value to a
J/g to figure out which fuel. You should get 36 kJ/g which does not match any
of the results. BUT this is the results of a STUDENTS experiment. Thus all the
values are going to be UNDERESTIMATES. Thus the student would have always got a
number LOWER than the theoretical value – ie lower then 36. So the correct
sample must be…
2011
Q17) This is a DEMONSAUD Question - HINT - you have ben given q and DcH for propan-1-ol...what can you find the number of moles of...?
2012
Q30bii) Why might we add ethanol to a solution when trying to dissolve something in water?
