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lol i was stuck on that question so long cos i wasnt bothered to read the steps. I thought the picture of the pipette was the burette for a long time

im quite sure that you overestimate HCl. the actual number of moles of sodium carbonate in the conical flask is less than what you calculate (since you incorrectly rinsed and filled the pipette). hence a lower volume of HCl will be used in the titration and you will get a higher concentration

wait, are you still talking about question5 ?

no its A

i put D for 13 as well. it could be A though if they did cellulose--->glucose--->ethanol--->ethylene--->polyethylene. Maybe they'll accept both answers? i think Its been done in the past

i think for hsc chem you USUALLY give answers to to the lowest sig figs in the question. dont think they will deduct a mark though

atomic number. e.g. carbon is element6

can we discuss options here? or new thread? i wanted to ask what people wrote for the sulfuric acid 7marker n industrial

^ did you convert your mass to kilograms OR your heat to joules specific heat capacity is usually expressed as X Kj/Kg.degrees or X J/g/degrees EDIT: just saw the back of the periodic table. the heat capacity can also be written as J/kg/ degrees

^ thats what i wrote. but didnt talk about neutral since you dont know where the equilibrium position lies normally. You should mention that its an appropriate indicator since it gives two distinct colours in acidic and basic solutions, thus allowing us to identify them as acids or bases.

for the next question find moles of ethanol n(ethanol) = 0.249/46... = 0.005...moles (i cant remember the exact numbers) Find heat released by this sample q= 0.005 x 1367 = 7... Kj now mass oil = 0.12kg and temperature change is 30degrees (it is not 20 because final temp occurs when heating...

First write out the equation: Pb + 2AgNO3 ----> Pb(NO3)2 + 2Ag Initial moles of Pb = (20.72g) / (207.2g/mol) = 0.1moles Initial moles of Ag+ = 0.1 L x 1 mol/L = 0.1moles now for a complete reaction n(Pb):n(Ag+) = 1:2 therefore all 0.1 moles of Ag+ has reacted to form Ag solid and only 0.05...

re: HSC Physics Marathon Archive ^LOL

re: HSC Physics Marathon Archive i wont post my working yet. But is the answer: acceleration is -4.8m/s/s and max height 173.4m

re: HSC Chemistry Marathon Archive maybe water is the only liquid that can affect an equilibrium, even though it has a constant concentration. I think that the proper explanation is that adding water will decrease the concetration of H2CO3 which causes the equilibrium to shift right

re: HSC Chemistry Marathon Archive Dont think so. Aqueous solutions are dissolved in water. So maybe water is a special case.

re: HSC Chemistry Marathon Archive Lol now im confused about the whole liquids thing. In esterification the textbook says that a sulfuric acid catalyst is used to remove water from the system to shift the equilibrium to favour ester yield. But liquids aren't supposed to affect equilibrium...

re: HSC Chemistry Marathon Archive A solution is not the same as a liquid. I think Heroic is right. Liquids have a constant concentration and will not affect equilibrium. Only the addition/removal of gases and aqueous solutions do have an effect. Edit: for industrial students, remember when...

re: HSC Physics Marathon Archive lol i got 0degrees and 35minutes and 89degrees 27minutes

re: HSC Chemistry Marathon Archive I took the question from HSC 2002 and the marking notes says : Where a question asks for plural responses, as indicated by developments and biopolymers, candidates must supply more than one example in their answer. A question asking about current developments...