600x50 is refer to total work done

25 E..? me correct?

yes, for example
Mg + H₂SO₄ -> MgSO₄ + H₂
Mg located higher than H, then it can grab or "rampas" the SO₄ ^2- from H

while for Cu
Cu + H₂SO₄ -> no reaction
Cu is lower than H in ECS, it cant grab or "rampas" the SO₄ ^2- from H.

This post has been edited by nicoleycc: Nov 1 2008, 01:43 PM

oh. ic. if it wants total work done then 600x50.
if work done against friction is 1000x50.
i understand now. thx

haha..i also think that 25 D le..hehe

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Added on November 1, 2008, 12:37 pm1600 x 50 is the total work done rite?? then work done to overcome friction is just take the frictional force x displacement

This post has been edited by vick5821: Nov 1 2008, 12:37 PM

It depends on how question defines "total work done". Ya, 1600x50 is better.
600x50 is the work done to rise the wood log.

phy ques..

Tension = pvg-mg=(1.25)(1200)(10)-(800)(10)=15000-8000=7000N

Hi guys I got a Q I wanna ask, hope u can help

Which of the following pairs of substances is most suitable to prepare copper(II) sulphate
salt?

A. Copper with dilute sulphuric acid
B. Copper(II) chloride with dilute sulphuric acid
C. Copper(II) carbonate with dilute sulphuric acid
D. Copper(II) nitrate solution with sodium sulphate solution

i remember success book mentioned all nitrate salts are soluble .

sodium salts are soluble also .

so i will choose D

CuSO4 is soluble salt. D is definitely not possible.. this is no double decompostition reaction.
A is not possible because Hydrogen is more reactive than copper metal.
I would choose C.

to get CuSO4 there are 3 ways. copper oxide with sulphuric acid, copper hydroxide with sulphuric acid or copper carbonate with sulphuric acid.

Yup you are right, answer given is C
just wanna try asking here cuz cant find explanation in my books. Thx

btw, CluelessNick, its your Bday right? Congratz

how u know D is double decomposition reaction?

it's not. if it were then a precipitate would form. double decomposition reaction only occurs when 2 soluble salt solutions are mixed together and an insoluble salt is formed. since cuso42 is soluble, hence no precipitate will form.

Double decomposition will produce insouble salt.

From D, Cu(NO3)2 + Na2SO4 --> CuSO4 + 2NaNO3
[This reaction is not double decompostion]

There is no insoluble salt produced, and we cannot separate the two solution. Thus D is wrong.

oh..double decompostion reaction is two soluble salt mixed toghether

yes. right

no 15 pls !

one add math ques.. solve the equation 2 + 2log 4 (p-6) = log 2 p

p/s the 4 and 2 are the base

There is 4 way to prepare soluble salt...
But 1 of them is only for SAP salt..Other 3 ways is for other soluble salt..

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Added on November 1, 2008, 7:21 pmAnswer is B...
At the dotted line there pressure is equal...Meaning that use formula hpg+atm

This post has been edited by gzavincent: Nov 1 2008, 07:21 PM