CHEM AND BIO HELP AND TIPS HERE

[holtadit]

i really dont understand anything in moles......can some1 gimme a site where they explain how to calculate moles easily? thanks.

http://thenightdreamer.wordpress.com/2010/03/19/moles/

The link takes you to my website. It may help you.

Like I said post a question you dont understand and we'll help you

[guMnam]

Thanks

[basharooo]

guys this question is freaking me out ( it is from igcse study guide for chemistry ,
about stoichiometry pg31

sample q 5
calcaluate the volume of sodium hydroxide , concentration of 0.16 mol/dm3 , needed to neutralise 20 cm3
of sulphric acid , concentration  0.2 mol/dm3 .

the eqation is 2NaOH+H2SO4--->Na2SO4+H20
-------------------------------------------------------
the answer is moles of H2SO4 = 20 divided by 10000 * 0.2 = 0.004
??

know why divided by 10000



 

[Vin]

to convert cm³ to dm³ (decimeter cube) ...  dm³  is used ALWAYS

[basharooo]

to convert cm³ to dm³ (decimeter cube) ...  dm³  is used ALWAYS

yea but isn't 1dm3=1000cm3
so 20cm3 *1dm3 divided by 1000 will not give 10000dm3 ??
 

[Ivo]

guys this question is freaking me out ( it is from igcse study guide for chemistry ,
about stoichiometry pg31

sample q 5
calcaluate the volume of sodium hydroxide , concentration of 0.16 mol/dm3 , needed to neutralise 20 cm3
of sulphric acid , concentration  0.2 mol/dm3 .

the eqation is 2NaOH+H2SO4--->Na2SO4+H20
-------------------------------------------------------
the answer is moles of H2SO4 = 20 divided by 10000 * 0.2 = 0.004
??

know why divided by 10000



 

Moles of sulphuric acid = 0.2*0.02=0.004

Moles of sodium hydroxide = 0.004*2=0.008

Volume of sodium hydroxide = 0.008/0.16=0.05dm³ or 50cm³

[Ivo]

yea but isn't 1dm3=1000cm3
so 20cm3 *1dm3 divided by 1000 will not give 10000dm3 ??
 

Since it's from a textbook, there are always typos .  I can confirm to convert cm³ to dm³, you divide by 1000.  So the book is wrong

[basharooo]

Moles of sulphuric acid = 0.2*0.02

Moles of sodium hydroxide = 0.02*2=0.04

Volume of sodium hydroxide = 0.04/0.16=0.25dm³

THX BUT THE ANSWER IN MY BOOK SAYS O.05 DM3 AND U ANSWER WILL BE 0.25?

[Ivo]

THX BUT THE ANSWER IN MY BOOK SAYS O.05 DM3 AND U ANSWER WILL BE 0.25?

Sorry my mistake.  I've edited the post.

Moles of sulphuric acid = 0.2*0.02=0.004

Moles of sodium hydroxide = 0.004*2=0.008

Volume of sodium hydroxide = 0.008/0.16=0.05dm³ or 50cm³

[Vin]

Sorry my mistake.  I've edited the post.

Exactly I was kinda wondering ...

[basharooo]

THX

[Ivo]

I've included some information about salt preparations, I hope this is useful for you.

[High-R]

I've included some information about salt preparations, I hope this is useful for you.

Thanks for this dude!!!
ur awsum!!...=D
 

[7ooD]

i have a quick question the formula for acids is cnh2n+1 cooh but i read that there is a new formula which works the same cnh2n o2 how can it be the same

[Ivo]

i have a quick question the formula for acids is cnh2n+1 cooh but i read that there is a new formula which works the same cnh2n o2 how can it be the same

I don't see how the second one can possibly work.  It is definitely C_nH_2n+1COOH.

The functional group is -COOH so I can't see how that can change.