Author Topic: Chemistry Help HERE ONLY !!  (Read 106213 times)

Offline X Abdulrahman X

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Re: Chemistry Help HERE ONLY !!
« Reply #345 on: May 29, 2009, 06:37:37 pm »
nope, a higher concentration of sulphuric acid means the bulb will light more, imagine u have a beaker filled with water and little sulphuric acid, then the bulb would be very dull, but if u have little water and lots of sulphuric acid then it would be brighter
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Offline AN10

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Re: Chemistry Help HERE ONLY !!
« Reply #346 on: May 29, 2009, 06:40:35 pm »
i guess u r ite
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Offline pedrojosetrujillo

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MOLES
« Reply #347 on: May 29, 2009, 06:42:39 pm »
How do you claculate the Moles of a gas and how do you calaculate concetration?

Offline care

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Re: MOLES
« Reply #348 on: May 29, 2009, 06:47:34 pm »
n = V / V(m)        (V(m)=24 dm^3/mol)

c = n / V

Offline astarmathsandphysics

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Re: Chemistry Help HERE ONLY !!
« Reply #349 on: May 29, 2009, 07:24:14 pm »
During electrolysis, what is the effect of adding water to dilute sulfuric acid on the brightness of bulb ???

it decreases - i think as the concentration is decreased

Offline islu_jf

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Re: Chemistry Help HERE ONLY !!
« Reply #350 on: May 29, 2009, 07:40:43 pm »
How can u test if the acid is weak or Strong... ??
other than PH???

Offline kam

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Re: Chemistry Help HERE ONLY !!
« Reply #351 on: May 29, 2009, 07:43:40 pm »
How can u test if the acid is weak or Strong... ??
other than PH???

universal indicator

Offline islu_jf

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Re: Chemistry Help HERE ONLY !!
« Reply #352 on: May 29, 2009, 07:45:02 pm »
isnt there any other way??!

Offline AN10

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Re: Chemistry Help HERE ONLY !!
« Reply #353 on: May 29, 2009, 07:49:07 pm »
-by investigating the rate of reaction of da 2 acids- for eg reaction b/w an acid and a metal, measure the volume of hydrogen gas given over a certain time interval, calculate the rate of reaction, the strong acid has a higher rate of reaction.

- by electrolysis of the two acids, as strong acid ionizes fully, the bulb will be more bright.
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Offline cactus_360

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Re: Chemistry Help HERE ONLY !!
« Reply #354 on: May 29, 2009, 07:57:58 pm »
at da same concentration the stronger acid will be a better conductor of electricty
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Offline Summer :]

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Re: Chemistry Help HERE ONLY !!
« Reply #355 on: May 29, 2009, 08:00:04 pm »
isnt there any other way??!

In a strong acid, all of the molecules when dissolved in water turn into ions
and in a weak acid not all of the molecules turn into ions

so you could simply dissolve them in water and use a Conductivity meter and measure there conductivity, if their conductivity is higher (due to the presence of more ions to carry the charge then it must be a strong acid)
if their conducitivity is pretty low (due to lack of ions then it must be a weak acid)

Offline Summer :]

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Re: Chemistry 2009!!! Paper 3 prep.....
« Reply #356 on: May 29, 2009, 09:58:35 pm »
thats interesting, i got a whole bunch of different answers

Potassium Iodide is a reducing agent which means it brings about the reduction of others but itself is oxidised so for example you can test for it, by adding potassium manganate which is an oxidising agent it will bring about the oxidation of potassium iodide and itself will be reduced.

Potassium Manganate - will change from purple to colourless it has been reduced
Potassium Iodide - will change from colourless to orange because it has been oxidised to Iodine

OR...
when potassium iodide is added to hydrogen peroxide and sulphuric acid
the products will be iodine,potassim sulphate and water

H2O2 + 2KL + H2SO4 --> I2 + K2SO4 + 2H2O

you can note that hydrogen peroxide has been reduced (loses oxygen) and potassium iodide has acted as the reducing agent where it has been oxidised..
2I- ---> I2
(Colouless) to (red-brown)

My mum is a chemical engineer so she helps me alot with those kinda stuff  :P  :)

Offline unknown 101

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Re: Chemistry Help HERE ONLY !!
« Reply #357 on: May 29, 2009, 10:22:51 pm »
How can u test if the acid is weak or Strong... ??
other than PH???
a strong acid would completley dissociate in water
a weak acid partially dissociates in water
this could be used to define the term strong acid and weak acid

othr than pH u could do a reaction, maybe acid + alkali (nuetralization)
use same volume and conc. of alkali, and see which acid neutralizes the alkali the fastest

Offline islu_jf

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Re: Chemistry Help HERE ONLY !!
« Reply #358 on: May 29, 2009, 10:52:46 pm »
ohhhhhhhhh i got it..
Thanx guys..

Offline AS girl

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Re: Chemistry Help HERE ONLY !!
« Reply #359 on: May 30, 2009, 12:20:51 am »
We don't need to know more than this about bond forming and breaking right?

This is the only thing u need to know about
Bond breaking=exothermic(negative)
Bond formation=endothermic (positive)

 ;)
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