mak10

I didn't understand.... if you are just given a compd like the one I mentioned and asked to draw a cis-trans isomer, how would go about doing it? -mak10

If a species more intelligent than the current race of homo homo sapiens ever evolve... then would we be to them, what apes are to us ?? I can't imagine such a scenario... they might find us weird, designate a special area solely for humans (like a human zoo or something), do various tests on, have us as their guinea pigs etc.. the possibilities are endless. Come to think of it, it would make a good movie with keanu reeves in it!! -mak10

What if the molecule was more like ClFC=CBrI ..... would there be cis-trans isomers here?? If so, how would you determine it as either cis or trans ?? -mak10

You can use F=ke here? First find total force which is 20N and find the extension for this using F=ke. Then using 10N alone find extension for 1kg. Deduct the two values and you will find the height 1 kg will reach. Do confirm this with your teacher, though. since the mass is given, use 1/2mv^2 = mgh for both a and b. For a, you have the v... so use plug in the values to get h(max). For b, use h(max) + 18 to obtain the value for v. The answers will be the same as TokenMonkey's though. -mak10

I have chemistry in context by Hill and Holman and it gives only a one page (p.420) description of cis-trans isomerism giving very simple examples like 1,2-dibromoethene. Our teacher did provide us with many examples and I remember her giving it from some Collins Chemistry book.... but nonetheless, none of her examples had four different substituents around a C=C. This maybe a bit higher stuff that I may not be aware of... but why, on earth, did the examiners put this in a typical AS-Level paper... I wonder. I tried to look for this stuff online but in vain. Any description of this type of cis-trans isomerism, however, would be very helpful. Thanks!! -mak10

but isn't mass supposed to be in SI units (kg) in order to us it in equations of this sort (P = F X V) ?? And i think its more like 1N application producing a velocity of 1 m/s = 1 W. don't know if its right though... -mak10

why divide 80t by 100g??

So in this structure: R-C=C-CH2OH (in order to view the structure properly, click 'Quote' at the bottom) l l CH3 H The bromine will add in the second carbon atom (starting from the left) and hydrogen will added in the third one?? (Note that R- indicates a long range of CHs).

Yeah, it was Geraniol and its plant-based. The problem is... i can't imagine a possible cis or trans isomer of this substance. I drew the full displayed structure and according to jdurg, you dont require the same group to be on either sides of the carbon for cis-trans isomerism.... then how can we classify whther a compound is cis (has two same groups on one side of the carbon atoms) or trans (has two same groups on opposite sides of the carbon atoms). As I said, I drew the full structure and the closest I could get is this: CH3-C=C-H l l C6H11 CH2OH if this isn't clear, there is a C6H11 group attached to the first carbon atom and CH2OH group attached to the second one. My question is, how, pray tell, can we determine cis-trans isomers without identifying the position of similar groups around the C=C ?? Thanks! -mak10

given the values, we can only know the force of impact when the object comes in contact with the wall.... by first determining its momentum and then dividing it by the time it stays in contact with the wall. atleast, thats what i think! -mak10

F = m x a Therefore... Newton = Kg m/s^2

when acceleration = 0, velocity = constant but non-zero. -mak10

ok, the structure isn't very clear. Just note, that the methyl group CH3 is actually attached to the carbon atom that is attached to an R-group and the H is with the adjacent carbon atom. -mak10

I had a few questions in my exam that I found a bit troublesome: 1. there is this substance called germinol with the structure: R-C=C-CH2OH (let me know if it isnt clear) l l CH3 H and we were asked to draw a cis-trans isomer of this structure. Now, as far as i know, it isnt possible since cis-trans isomers occur only when the double bonded carbon atom have at least one similar pair of a group/substance, attached to each one. Am I correct here or I screwed up leaving this question blank?? 2. for the above substance, what will be the structure of the organic product if it reacts with HBr?? -mak10

displacement reactions are those where a particular molecule/element in a compound gets displaced by a more reactive molecule/element in that compound, by a reaction. Like when chlorine displaces iodine from KI and forms KCl in a reaction.... since it is more electronegative and thus reactive than iodine. It can occur in solutions as well as in gaseous reactions... i think. -mak10

Yes. Oxides of metals are ionic and all ionic compounds are soluble in water. Potassium reacts with water, produces potassium hydroxide which 'dissolves' in water... meaning it is present is a dissociated form = K+ and OH- surrrounded by water molecules. the complete chemical equation goes something like: 2K(s) + 2H2O(l) = 2KOH(aq) + H2(g) Regards, mak10

come to think of it, solid ethanol may possess the same porperties. but the difference may well lie in more number of van der waals forces and less hydrogen bonding... not sure about it though!

I'd be voting for ice, since: 1) it possesses lots of hydrogen bonding 2) and oxygen is more electronegative that nitrogen and this may contribute to a stronger hydrogen bonding than ammonia. Regards -mak10

My bad... I confused reactivity with solubility. I stand corrected! Regards, -mak10

If I understand your question correctly, I think you're thinking in terms of ionic equations where metals losing an electron is represented as a cation. For instance, the equation: Na + H2O ==> NaOH + H2 .... can be also written as: Na ==> Na+ + e- [1 electron] As you can see, the ionic equation doesn't really happen in real life... it only shows whats happening to the individual elements and compounds in a reaction. I hope this is answers it... Regards, mak10

Metals do react and dissolve in water. Why, some (like potassium and sodium) are sooo reactive, in contact with water, that the reaction is explosive!! The metallic lattice, in general, is composed of positively charged atoms (or some would call, 'metal ions') surrounded by a sea of delocalised electrons and it is this electrostatic force of attraction that gets broken by water molecules during hydrolysis.... if I am not wrong. Regards, mak10

I've been to the site and most of the articles there are by Bin Baz who was proclaimed 'heretic' by the majority of Muslims. why, he even went on to state that the earth is flat and any Muslim who believes otherwise, is a kafir [non-Muslim]!! So I dont think that website is suitable for discussing the implications of science in koran. But there is a good book written on it that I would recommend... its by Dr. Maurice Bucaille entitled La Bible le Coran et la Science (The Bible, the Koran and Science). Its a an interesting read! Another good site with lots of info is: http://www.it-is-truth.org/Index.shtml -mak10

well, it says I am an idealist... but i would consider myself to be more of a realist. It was good fun though, thx for the link!

if so, i would be interested in knowing the results you obtained in the practical exam that was held today. thx! -mak10 P.S: I am talking about the Cambridge board AS chemistry practicals that was held today.

A-levels are tough yo! I am currently doing the fast-track A-level (that covers the entire A-Levels in 1 year) and it ain't easy... when compared to the past A-level papers, at least not for bio, chem and physics.... thats for sure!