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Is Molarity just another name for concentration, because i cant see anything in book

I was working on this question , which seems simple but confused me towards the end.

Calculate the molarity of the first named solution:

25 cm^3 of sodium hydroxide reacts with 17.0 cm^3 of 0.1 mol dm^-3 H2SO4

i converted 25 cm3 to 25/1000 dm^3
then converted 17.0 cm3 to 17/1000dm^3 and multiplied it by 0.1 to obtain
17/10000
then got common denominator for 25/1000
so i then did 250/17 = 14.7

I dont know now whether to times it by 0.1 as well. Please help!

Reply 1

EierVonSatan

Molarity is another name for concentration in mol dm^-3

moles of acid = 1.7E-3 => 3.4E-3 moles of NaOH

conc = mol/vol = [3.4E-3/(25/1000)] = 0.136 M

Reply 2

Muppety_Kid

...bored

I don't feel qualified to answer this question, but my understanding is that molarity is a measure of concentration. A solution of 2M is (twice/ten times? I think it's twice) as concentrated as a solution of 1M. I think it's something to do with the number of atoms of the "chemical" per...

As you can see, I'm really not sure. :s-smilie:

Why not consult Wikipedia while you wait for some answers?

Reply 3

Clarfairy

moles is the concentration times the volume.
concentration is different, as the concentration of a solution is the amount of solute in moles dissolved into 1dm^3 of solution. the moles for it are mol dm^3 :smile:

Reply 4

Clarfairy

hm ok i'll go more in depth, im sorry if i am rusty as i've had all summer to empty my brain!

NaOH is reacting with H2SO4.
since its H2, the 'ratio' that we need so to speak is 2 NaOH to 1 H2SO4
since an acid donates one H+ to the bases OH- to make the H2O.

anyyywayy!

the moles of H2SO4 are 0.017*0.1 = 0.0017.
we DOUBLE (eek!) this to get the moles of NaOH = 0.0034

i'm so sorry if this is wrong, like i said i'm rusty >_< i suck :tongue:

Reply 5

EierVonSatan

Clarfairy

hm ok i'll go more in depth, im sorry if i am rusty as i've had all summer to empty my brain!

NaOH is reacting with H2SO4.
since its H2, the 'ratio' that we need so to speak is 1 NaOH to 2 H2SO4
since an acid donates one H+ to the bases OH- to make the H2O.

anyyywayy!

the moles of H2SO4 are 0.017*0.1 = 0.0017.
we half this to get the moles of NaOH = 0.00085

i'm so sorry if this is wrong, like i said i'm rusty >_< i suck :tongue:

2NaOH + H2SO4 ---> 2H2O + Na2SO4

double the moles...

Reply 6

Dstbgre

0.1/1000 x 17 = number of moles H2SO4 used

= 0.0017

Stoichiometry of the reaction is 2:1 i.e. 2 moles NaOH reacts with 1 mole H2SO4

2NaOH + H2SO4 --> 2H2O + Na2SO4

So if you multiply the number of moles of acid used by 2 you get the number of moles NaOH used

= 0.0034 moles NaOH used

Therefore 0.0034/25 x 1000 = conc of NaOH

= 0.136 M

Reply 7

...bored

Thank ou evryone. The book does not explain this, nor does our teacher yet we got these questions for homework. Im having words with the teacher.