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Thank you! Do you think that would apply to Potassium Iodide solid too?

About 6 years ago, I made a precipitate of Lead Iodide in water by mixing Potassium Iodide and Lead Nitrate. I have kept the precipitate in a test tube. Would anybody know how stable is the precipitate over time. The temperature has been mostly between 20 and 32 degrees depending on the...

http://faculty.southwest.tn.edu/jiwilliams/probab2.gif using the above table, first thing you select the row for your degrees of freedom. in your case, it is 3. now this row tells us, if your chi square value is less than 0.35, then the probability of this particular event occurring is greater...

capillaries cannot constrict because they consist only of endothelial cells, and no muscle cells at all.

i would suggest that since air is made up of about 78% nitrogen, you could substitute the nitrogen with air. anyway, there is already a 15% error in the equation. the error due to the substitution of nitrogen by air should not be very significant. i might as well be wrong!

how about expansion and contraction due to temperature changes?!

Using the Le Chatelier's Principle, then there will be no charge on the phosphate because it would remain undissociated! Is that it? ooo but then, the charge will depend on the pH, while, the polarity will always be here! so, in a sense, it is better to say C! right?

since phosphoric acid is a weak acid, it's pKa should be between 2 - 6. Therefore at physiological pH 7.4, the acid will be dissociated, giving the negatively charged anion. Am I correct? If, the pH is very low, in strongly acidic conditions, then the phospholipid will be uncharged.

Homework Statement Phospholipids have headgroups and hydrocarbon chains as follows: A. amphipathic, non polar B. non polar, polar C. polar, non polar D. charged, non polar Homework Equations phospholipids have a phosphate head group and fatty acid residue hydrocarbon tails...

Hi. Do you guys have an idea of what kind of careers are open with a BScHuman Biology degree! And, according to you, which may be more beneficial, a fourth year doing an undergraduate Master (research based) or a 4th year spent on industrial experience? Thank You Kushal

and i would like to point out all those siamese babies and the rare cases of abnormally born babies, these are concrete examples! When an indian baby girl was born with four arms and four legs! http://www.foxnews.com/story/0,2933,308439,00.html now this is not something favourable today. we...

yes it does amaze me, that's why I'm doing a career in biology/biomedicine! destruction of mankind could also be a sort of progression! look at what all other organisms have to go through because of us! polluted lakes, melting of ice caps, slaughtering! If you remove human impact, all other...

I find science more interesting than religion! science is dynamic, you can change it! but religion is static! it talks about the past, one day it will definitely contradict itself. but science will always alter itself to suit new laws! these laws are proven! evolution is completely random...

for interphase g1 you meant 23 chromosomes? it should be 23 pairs of chromosomes! making you 46 chromosomes in all. 23 chromosomes from mum and 23 chromosomes from dad. then you should correct all the numbers accordingly. and why would the number of chromosomes be halved from interphase s...

i never came across benzoyl peroxide. I would suggest that it would break Br2 into Br+ and Br-. The Br+ is accepted by the benzene ring (electrophilic substitution rxn) and the Br- would attack the hydrocarbon as a radical. but i really don't know.

I don't think fractional distillation would be called gravimetric analysis. You should go for a heat to constant mass analysis. What do you know about mercury oxide when heated?

what can be observed is that when the molecular mass increases, ie you are adding more -CH2 groups, the boiling point is increasing. you can use a knowledge of temporary dipole forces of attractions. probably for the solids, the shape the alcohols take matters more. methanol, ethanol and...

hint: can you calculate the number of moles of CO2 you obtain?! If the products are CO2 and H2O only, then all the Carbon from the initial material have gone into CO2. so, if you have x mol of CO2 formed, then you should have had x mol of Carbon in the initial substance. Using this same logic...

maybe the question wants you to look at the surface area to volume ratio. just like children will require more energy than adults for their daily metabolic activities!

i may be wrong but i think that you would see up to metaphase. because, if i remember my biology well, the chromatids will line up at the equator of the cell. It is only in anaphase that the spindle come into action to pull apart the sister chromatids to opposite poles. the absence of spindles...

hint: think about density of hot and cold air.

if I'm not wrong, you should consider the typical test for starch, with iodine forming a blue black complex with the starch. the halides are reducing agents. and the bleach is an oxidising agent.

awww... i put only a few drops of concentrated H2SO4... but it's only 2 marks...nvm we had to distinguish between an amide and a primary amine. i had completely forgotten about the NaOH reaction which could have been used... thnks

Homework Statement does ethanamide react with ethanol forming an ester?! Homework Equations CH3CONH2 + CH3CH2OH -------> CH3COOCH2CH3 + NH3 The Attempt at a Solution

i would use the inductive effect to explain the acidity of acetic acid and 2 hydroxy acetic acid. the oxygen on the hydroxyl group of 2 hydroxy acetic acid is of course electronegative. it tends to pull electrons towards itself. the carbon of -COOH will have a lesser electron density, and the...

i would get 2 equations for ax+b. then i'll be able to solve for a and b simultaneously...:) i hope this is correct. thnks

ermm well it will be in the form (x + a) but how do i find a?

Homework Statement when the polynomial f(x) is divided by (x-1) the remainder is 2, and when f(x) is divided by (x-3) the remainder is 4. Find the remainder when f(x) is divided by x2 - 4x + 3. The Attempt at a Solution i thought of adding the remainders since x2 - 4x + 3 =...

errmmm it's been solved... it was as simple as replacing the x in g(x) by x2 thanks anyway

Homework Statement part of the question is: g:x = b - \sqrt[3]{x} x is real Solve g(x2) = g(x) - 6 Show that: g(x6) + 4g(x3) \leq 5b + 4 for all real values of x The Attempt at a Solution If i at least have a hint on how to start the first part i guess i'll be...

ooo yeah... i should use the absolute scale right?! i don't know why it was not obvious at the beginning... thnks:)

Homework Statement Comment on the statement 'Today the temperature is 40\circC and yesterday it was 20\circC so it is twice as hot today as it was yesterday.' The Attempt at a Solution i feel that it is wrong to say that, although i think a body at 40\circC is twice as hot as a body at...

niice analogies lol... thank you borek and epenguin... i can get the picture now:)

so you mean that when the carbanion forms a trigonal bipyramidal structure, the R1, R2 and R3 lie on one plane with the Br and OH perpendicular to that plane. but how does the switching occur?! does it occur after the Br- leaves? thnks

i had a look at the mechanism but i can't find how there could be a reversal in chirality. a hint would be well appreciated. thnks

ermmm well i tried to imagine but i still can't see how a dextro or leavo enantiomer could become the opposite?! because the Br- will go and the OH- will just attach to the electron deficient carbon. does that have something to do with the SN2 mechanism?

Homework Statement when chiral 2-bromobutane reacts with aqueous hydroxide ions, the optical activity of the product is reversed. Suggest why the optical isomerism is reversed. The Attempt at a Solution i have no idea... but i don't know if the fact that the hydroxide ion will attack...

thnks:)

ooo ok... the question is from a past past past exam paper...lol... i guess we won't be getting such questions in the finals... because i didn't find any deamination or dealkylation reaction in the syllabus... thnks again...:)

it seems that hydrogen has been added. but i can't find any type of reaction involving hydrogen like this. i would rather think of a species which is a stronger nucleophile than the 'ammonium stuff' since the carbon attached to the - NH - has a partial positive charge. but could it be a...

density of pure water and impure water are different... as you said, density = mass/volume. what do you think will happen to the mass and volume when salt is added to the water?!

i'm afraid i may not be an exact source for the equation of perchlorate as an oxidising agent. but, i know that Cl can have oxidation states: -1, +1, +3, +5 and + 7. if the perchlorate (+7) is reduced to chlorate (+5), then the equation is: 2H+ + ClO4- + 2e- ------> ClO3- + H2O i placed H+...

metals are reducing agents and the perchlorate is an oxidising agent.

Homework Statement Part of a long question: suggest the type of reaction occurring: (C6H5)3C-NH-CH(CH3)-CO-NHCH2COOH -----> (C6H5)3C-H + NH2-CH(CH3)-CO-NHCH2COOH The Attempt at a Solution what i got in mind is that it could a free radical substitution reaction?! using H2...

i guess this makes more sense!

yeah you're right, i completely ignored that. a small current might not be able to operate the appliance. errmm i still can't find the second reason... a hint would be great...lol thnks

Homework Statement Some electrical appliances are used with long cables to connect to them to the electrical supply. State and explain 2 reasons why these cables should have a low resistance per unit length. The Attempt at a Solution well for the long cables, a low resistance per...

errm p.d refers to the potential difference between two points.

Homework Statement V = IR is used to define resistance. why can't it be used to define p.d.? The Attempt at a Solution i suggested that sometimes the current can be zero, but there is a p.d. so the equation does not hold. but my teacher says that the answer is more towards the...

the rate of reaction is already slow because of the acetone and H+ reacting. if you use low concentrations of them, the reaction would be even slower. and since iodine is zero order, using a very low concentration does not affect the rate. probably you have been given low concentration because...