AS Level Volumetric calculations

Can someone please show me how I would go about solving this;

Calculate the molarity of the first named solution from the data below

25cm3 of sodium hydroxide reacts with 21.0cm3 of 0.2mol dm-3 HCL

Thank you.

Reply 1

lebanon4ever

C1V1=C2V2
(21.0)x(0.2)=C2(25)
C2=0.17M

Reply 2

KoRnMaNiaC

can you please elaborate on what you did there? the teacher didn't really explain it to me.

Reply 3

Miss_Scarlett

lebanon4ever

C1V1=C2V2
(21.0)x(0.2)=C2(25)
C2=0.17M

Concentration1 x Volume 1= concentration2 x volume 2
If it's a 1:1 to relationship in the equation of reactants and products.

Therefore in this case:

0.2 x 21= concentration2 x 25cm3
rearrange so:
Concentration= 0.17M
remember if you need it in dm3 to divide by 1000.... i.e 21cm3 = 21/1000=0.021dm3

If you apply the following you can rearrange to find any of the values:

no. of moles= Mass in grams/ relative formula mass ...in solution : no.moles= volume x concentration
=vol/1000 x conc (for anwers in dm3)

In Gaseous state: No.moles= vol/24 or if the volume is in cm3 No moles=vol/24000

Hope this helps :smile:

p.s ask your teacher to explain this the next time you see them, as it will form the basis for further calculations.
If you need any more help just ask- hope that wasnt too patronising and sorry for the lengthy post!! :biggrin: