Chemistry doubts..ask here!

[haochen]

Test for alcohol? :S

use potassium manganate
it will turn from purple to colorless

use potassium dichromate
it will change from orange to green

use:
it is use by the police to test if the driver have drank alcohol when driving.

hope u got it

Thank you

ur welcm

 

[omartwee]

sorry i just wanted to ask if you are sure that the product will be halved if the concentration is halved?!

yeah because less concentration so less molecule so less product

hope u got it

are u sure because i remember when doing graphs and they differ the concentration..the one with less conc..will be less steep but will end at the same volume of the first reaction indicating that the rate will differ but not the product it self :/

yes that was what i thought narutogirl so now i am somehow confused

 

[haochen]

hye
can any 1 tell me about tritation methods????

Theres just one method of titration i guess and that is:

for example lets say u want to titrate HCl with NaOH:

1-Fill NaOH into a burette
2-Measure a certain volume of HCl solution and transfer that into a conical flask
3-Add a few drops of phenolphthalein(indicator solution) into the conical flask
4-Carefully add HCl from the burette into the conical flask until you get a permanent pink colour
5-Record the final reading on the burette
6-repeat without the indicator (phenolphthalein)

Correct me people

u place the NaOH in the burette it should be in the flask and the HCL should be in th burette
correct ur 1, 2 , 4 line

 

[narutogirl]

hye
can any 1 tell me about tritation methods????

Theres just one method of titration i guess and that is:

for example lets say u want to titrate HCl with NaOH:

1-Fill NaOH into a burette
2-Measure a certain volume of HCl solution and transfer that into a conical flask
3-Add a few drops of phenolphthalein(indicator solution) into the conical flask
4-Carefully add HCl from the burette into the conical flask until you get a permanent pink colour
5-Record the final reading on the burette
6-repeat without the indicator (phenolphthalein)

Correct me people

when i do it i usually put the alkaline in the conical flask n the acid in the burrete, to avoid confusion u don't have to say which indicator did u put and just simply state that we add the acid from the burrete until the indicator changes its colour...and u note the amount of acid that was needed by the alkaline to get neutralized.

if u need the crystals from this method..u could say as u said repeat without the indicator and then u leave it till crystallization point where u then take the crystals and dry it between two filter papers

 

[angel786]

hye
can any 1 tell me about tritation methods????

it is when u react a base with and acid to form salt and water.

do u need the steps ?????

yes i need steps

 

[haochen]

sorry i just wanted to ask if you are sure that the product will be halved if the concentration is halved?!

yeah because less concentration so less molecule so less product

hope u got it

are u sure because i remember when doing graphs and they differ the concentration..the one with less conc..will be less steep but will end at the same volume of the first reaction indicating that the rate will differ but not the product it self :/

nooooo it is less steep and it doesnt join the line
there is two factor which doesnt join the line and one of them is concentration
go check again to make sure

 

[haochen]

hye
can any 1 tell me about tritation methods????

it is when u react a base with and acid to form salt and water.

do u need the steps ?????

yes i need steps

they already post it
fast source

 

[shan5674]

hye
can any 1 tell me about tritation methods????

Theres just one method of titration i guess and that is:

for example lets say u want to titrate HCl with NaOH:

1-Fill NaOH into a burette
2-Measure a certain volume of HCl solution and transfer that into a conical flask
3-Add a few drops of phenolphthalein(indicator solution) into the conical flask
4-Carefully add HCl from the burette into the conical flask until you get a permanent pink colour
5-Record the final reading on the burette
6-repeat without the indicator (phenolphthalein)

Correct me people

u place the NaOH in the burette it should be in the flask and the HCL should be in th burette
correct ur 1, 2 , 4 line

So if i did it the other way around the solution would change from pink to colourless right? :S coz i was taught that we can do it either way :/

 

[shan5674]

hye
can any 1 tell me about tritation methods????

Theres just one method of titration i guess and that is:

for example lets say u want to titrate HCl with NaOH:

1-Fill NaOH into a burette
2-Measure a certain volume of HCl solution and transfer that into a conical flask
3-Add a few drops of phenolphthalein(indicator solution) into the conical flask
4-Carefully add HCl from the burette into the conical flask until you get a permanent pink colour
5-Record the final reading on the burette
6-repeat without the indicator (phenolphthalein)

Correct me people

when i do it i usually put the alkaline in the conical flask n the acid in the burrete, to avoid confusion u don't have to say which indicator did u put and just simply state that we add the acid from the burrete until the indicator changes its colour...and u note the amount of acid that was needed by the alkaline to get neutralized.

if u need the crystals from this method..u could say as u said repeat without the indicator and then u leave it till crystallization point where u then take the crystals and dry it between two filter papers

But they usually ask for "named" indicator and correct colour change :S

 

[haochen]

nooooooo
u got it wrong
u said in 4 add HCL from the burette while in the burette it is NaOH
and dont use phenolphthalein because it is colouless in neutral and acid
so use methyl orange

 

[angel786]

hye
can any 1 tell me about tritation methods????

Theres just one method of titration i guess and that is:

for example lets say u want to titrate HCl with NaOH:

1-Fill NaOH into a burette
2-Measure a certain volume of HCl solution and transfer that into a conical flask
3-Add a few drops of phenolphthalein(indicator solution) into the conical flask
4-Carefully add HCl from the burette into the conical flask until you get a permanent pink colour
5-Record the final reading on the burette
6-repeat without the indicator (phenolphthalein)

Correct me people

thanks

 

[shan5674]

nooooooo
u got it wrong
u said in 4 add HCL from the burette while in the burette it is NaOH
and dont use phenolphthalein because it is colouless in neutral and acid
so use methyl orange

oh lol my bad
So what is the colour change wit methyl orange?

 

[shan5674]

hye
can any 1 tell me about tritation methods????

Theres just one method of titration i guess and that is:

for example lets say u want to titrate HCl with NaOH:

1-Fill NaOH into a burette
2-Measure a certain volume of HCl solution and transfer that into a conical flask
3-Add a few drops of phenolphthalein(indicator solution) into the conical flask
4-Carefully add HCl from the burette into the conical flask until you get a permanent pink colour
5-Record the final reading on the burette
6-repeat without the indicator (phenolphthalein)

Correct me people

thanks

Welcome but please check out the corrections made by haochen

 

[haochen]

change 3 and 4 to :
3-Add a few drops of methyl orange(indicator solution) into the conical flask
4-Carefully add NaOH from the burette into the conical flask until you get a change in color from red to orange.

remember everyone especially narutogirl :
if u use acid in burette and base in flask the colour will change from yellow to orange
becoz in the flask there is a base which is yellow in methyl orange

hope u got it

 

[narutogirl]

nooooooo
u got it wrong
u said in 4 add HCL from the burette while in the burette it is NaOH
and dont use phenolphthalein because it is colouless in neutral and acid
so use methyl orange

oh lol my bad
So what is the colour change wit methyl orange?

my teacher always told me don't say the indicator's name because sometimes a certain indictator can't be used with certain reactions..so just say add drops of an indicator and then it will change colour ( don't worry my teacher has over 20 years experience and many students who studied with her got ranks)

 

[omartwee]

yeah because less concentration so less molecule so less product

hope u got it [/quote]

are u sure because i remember when doing graphs and they differ the concentration..the one with less conc..will be less steep but will end at the same volume of the first reaction indicating that the rate will differ but not the product it self :/[/quote]

nooooo it is less steep and it doesnt join the line
there is two factor which doesnt join the line and one of them is concentration
go check again to make sure [/quote]


Ok i think i got the answer!:
if we halved the concentration for the limiting reactant the product will be halved with slower rate.... if we halved the concentration for the reactant in excess this would give a slower reactin with the same amount of product..... i think it's that way

 

[shan5674]

nooooooo
u got it wrong
u said in 4 add HCL from the burette while in the burette it is NaOH
and dont use phenolphthalein because it is colouless in neutral and acid
so use methyl orange

oh lol my bad
So what is the colour change wit methyl orange?

my teacher always told me don't say the indicator's name because sometimes a certain indictator can't be used with certain reactions..so just say add drops of an indicator and then it will change colour ( don't worry my teacher has over 20 years experience and many students who studied with her got ranks)

Alright then i wont use the name easier for me but u better not be wrong about this
Thanks

 

[narutogirl]

yeah because less concentration so less molecule so less product

hope u got it

are u sure because i remember when doing graphs and they differ the concentration..the one with less conc..will be less steep but will end at the same volume of the first reaction indicating that the rate will differ but not the product it self :/[/quote]

nooooo it is less steep and it doesnt join the line
there is two factor which doesnt join the line and one of them is concentration
go check again to make sure [/quote]


Ok i think i got the answer!:
if we halved the concentration for the limiting reactant the product will be halved with slower rate.... if we halved the concentration for the reactant in excess this would give a slower reactin with the same amount of product..... i think it's that way[/quote]

hehe ya exactly..it depends who is the limiting reactant.

 

[haochen]

Ok i think i got the answer!:
if we halved the concentration for the limiting reactant the product will be halved with slower rate.... if we halved the concentration for the reactant in excess this would give a slower reactin with the same amount of product..... i think it's that way

the first on is correct but about the second one:
if u halve the excess and the excess become a limiting reactant it product will be less and the reaction will be slower
but if u halve the excess and it is still in excess than ur second one is correct

 

[shan5674]

Tap water
Sea water
Distilled water

In which sample of water does iron rust the fastest?