Jessieee

i have done an experiment using colourimeter to find the rate expression of the reaction between iodine and propanone. there were 3 sets of reaction mixtures 1. 4 cm3 of propanone, 2 cm3 of 0.05M iodine, 4 cm3 of 1M HCl, 4 cm3 of water 2. 2 cm3 of propanone, 2 cm3 of 0.05M iodine, 4 cm3 of 1M HCl, 6 cm3 of water 3. 4 cm3 of propanone, 2 cm3 of 0.05M iodine, 2 cm3 of 1M HCl, 6 cm3 of water i obtained 3 graphs of [i2] against time, and i found the slopes of them 1. -0.00647 2. -0.00367 3. -0.00375 what are the possible explanations for the slope of set 3 slightly greater than that of set 2?! is it only becoz there's some error when plotting the graph, or there are other reasons behind?! and also, i found that the initial temp of the 3 reaction mixtures being slightly different, why is it so? will this affect my result a litte? since temp affects the reaction rate.. thx alot!

we've done an experiment iodine reacts with propanone the reaction mixture contains -50 cm3 of 0.02 M I2 in aqueous KI solution -25 cm3 of H2SO4 -6.25cm3 of propanone -18.75am3 of distilled H2O while other groups used different volume of propanone and water but the total volume of reaction mixture is still 100cm3 and after mixing... After 5 minutes, pipette 10.00 cm3 of the reaction mixture into another conical flask containing 10 cm3 of the sodium hydrogencarbonate solution (measure this during the 5 minutes interval) noting the time at which this is done. Mix the solution thoroughly and then titrate with the diluted sodium thiosulphate solution using starch as indicator. After 10, 15, 20, 25 and 30 minutes withdraw 10.00 cm3 portions of the reaction mixture from the flask and carry out the above procedure each time. results... Time 5 10 15 20 25 30 35 40 45 Vol. 7.00 6.80 6.80 6.60 6.40 6.40 6.30 6.30 6.20 so a graph which vol of thiosulphate used against time was plotted... need to ans some questions.. 1. how can the rate of the reachtion be determined from the graph?! 2. did the iodine concentration change at a uniform rate throut the experiment?! (from my graph, i got "yes" as i seems like got a st.line graph) 3. is the rate of change of the iodine concentration dependent on the iodine concentration? (again, seems that it should be dependent, but from my graph, it's independent..lol, my graph isn't a curve, is it becoz the conc of propanone used is too low?!) 4. what is the order of the reaction with respect to iodine? (how can i get the ans!?) 5. does iodine take part in the rate determining step of this reaction? (how do i know?! i guess yes, but seems no evidence?!) 6. what is the significance of the intercept of the graph? (no idea..) 7. what must be the conc of the sodium thiosulphate solytion have been!? (how to calculate? do i know the conc of iodine??) sorri for soooooo many questions. stupid me.. >.<!

oh, i am reli sorri that i didn't make myself clear.. i mean the bonds between the lone pair of electrons on an O of one molecule the H of another molecule.. lol..

what is the approximate value of H bond strength in ethanol!? thxx...

well, i am not doing any experiment at home, instead, i am going to investigate the chemical principles behind some household stuffs, say for example, detergent... can u get the difference?!

any investigation on household chemistry which is not that complicated but interesting!? we 've tried to investigate effect of sugar in milk under heat(millard reaction or whatsoever) , but it's rather difficult to reach the conclusion.. thinking of changing topic now.. but time is limited.. help!

i know that when amino acid reacts with reducing sugar under heat, some brown substances will be formed, but is there any way to test the substances!? and what exactly the temp needed for heating?! thxx

soo... is there any way to test for it?

so u mean some of them are toxic!? coz i am doing some experiments to find out whether the hydroxylysine in milk when heated will produce toxic stuffs, and seems this is related to fructose or sth.. wanna find out if this is true...

any way to test for the presence of hydroxylysine?! also what is the structure of hydroxylysine? do milk contains hydroxylysine!? and do any compound of hydroxylysine is harmful to human body!? lots of questions, thz alot~!!! =)

we hv done a lab dertermining the heat of hydration of CuSO4(s) using the results from diluting anhydrous CuSO4 and CuSO4.5H2O in water... final ans obtained= 68.88 KJ/mol there is a question like that what is the significance of the heat of hydration of copper(II) sulphate? thx~

how? any more suggestions?

will it be too general?

lol.. i actually hv quite a long time to plan n carry out my investigation... i need to hand that in on early march i think... =) so it's preferred to be a SERIES of experiments on different "aspects" of the problem rather than a single one... and i find it difficult to find any topic which allows me to investigate several things on it... most of them i can only think of one investigation only...

hahaa... yea, you are rite!

but i think i am not going to make anything but instead to investigate the chem behind the existing stuffs at home... like... u know wok(a chinese cooking utensil)? there's always a layer of black stuffs (seems like to be fat or wtever, not very sure) that can prevent the wok from rusting... so we can find out how can it do that... n test the heat n electrical conductivity of that black stuff...blah blah blah... that's an example shown to us... arghh, hard to find one which is suitable n worth doing...

still the same opinion.. all those suggested seems didn't related to household isn't it? and i want some which hte results are not 2 obvious... i mean not those known by all ppl who hv studied chem...= ="

household chem... isn't abt the chemistry "theory" behind the stuffs at home? maybe like rusting/detergent or whatever.. but those are sooo common n boring, n were done by many ppl already... gotta try out some new things instead.., i am wondering if the one on milk plastics suits the theme...

well... lol... actually i am not very sure abt that... =________=|| maybe i should think of some topics that i would like to do n see if it's workable or not.. actually it need not be a complicated one, as long as it's creative n worth doing(may hv some applications or so... sooo... just give out any idea, i will try to sort out whether i hv those resources or not maybe later... i got a long period for this project actually...

actually i think we hv limited resources n apparatus, just those commonly found in the lab(not a very professional one of coz..=_=") em... abt safety... i think...... as long as we wont reli get hurt or sth will be ok..=_=" and those experiments will be carried out in the school lab, so.... i think it can't be too dangerous... or else it will be banned...haha...

well... actually the project aims to develop our creativity or some sort of problem solving skills..so it doesn't hv some precise rules actually..

well... we need to do some sort of project work on the topic household chemistry... it includes experiments, reports, investigation etc... i wanna get some new ideas... which means those hven't been done by someone else... not those common ones i mean... n better hv some actual applications, it may not be a well developed one tho... em... any ideas? =)

1. the formation of chemical bonds in molecules will result in a. the attraction between electrons b. the liberation of heat c. the attraction between nucei d. even distribution of electrons ans is b, but i wanna ask will it result in the attraction between anything, even not between neither the nuclei nor the electrons 2. which of the following statments abt redox reaction is false a. some common oxidizing agent can also be reducing agents in other reactions b. oxidation n reduction take place at the same time c. redox reactions involve electron transfer d. a current can be detected ans is d, i know why d is false, but i think a is not reli correct either... 3. hot conc sulphuric acid reacts with sodium chloride to form HCl gas. in this reaction, conc sulphuric acid acts as a. a strong acid b. an oxidizing agent c. a dehydrating agent d. a dibasic acid ans is a...is it only becoz it is a strong acid? 4. during the preparation of a greasy chinese dish, some peanut oil was stongly heated in a metal wok. it was found that the fumes didnt condense back to liquid on cooling. the formation of such fumes may be explained by the fact that a. combustion converted the oil molecules to CO2 n water b. oil molecules were converted to a polymer c. oil molecules were fragmented into smaller pieces d. oil was hydrolsed into acids n glycerol ans is c...no idea 5. which of the following statments abt the compound, CH3CH2COOH, is incorrect? a. it can undergo polymerisation b. it has a sour taste c. it can be made from ethanol d. it is a food preservatives ans is a, but i think it can undergo polymerisation 6. lather formed by detergent n water (1) kills fish in water (2) holds suspended dirt n grease in water (3) block the traffic in waterways which is/are true? a. 1 and 2 b. 1 n 3 c. 2 n 3 d. 1, 2 n3 ans is b, actually what is the lather? how is it form? 7. which of the following can undergo polymerisation (1) .... (2) NH2-CH2-CH2-CH2-CH2-CH2-COOH (3) NH2-CH2-CH2-CH2-CH2-CH2-OH y cant (3) undergo polymerisation? thats all...thx!