CHEMISTRY QUESTION - Titration

Work out the number of moles in the following solution (moles = concentration x volume):

a) 1dm3 of 2 mol/dm3 HCL:

b) 100cm3 of 1 mol/dm3 NaOH:

c) 25cm3 of 0.1 mol/dm3 NHO3

d) 10cm3 of 0.2 mol/dm3 Ca(OH)2


I dont understand, how to even find the concentration or volume in these questions, and apparently, we have to convert them, so that 1dm = 1000cm3 or something? Can someone explain these to me, even if it means just answering 2 or 3 of the questions as examples. Thanks so much :)

The reason for converting the 'dm3' into 'cm3' is that with the (Moles = Concentration x Volume) equation, each number inserted must be in its SI (standard) units. For volume, the unit is dm3; for concentration, the unit is mol/dm3, etc.

1dm3 = 1000cm3

E.g.

a) Moles = Concentration x Volume
= 1 x 2
= 3 moles

As all the values are already in SI units, there is no need to convert them.

b) 100cm3 = 0.1dm3

Moles = Concentration x Volume
= 1 x 0.1
= 0.1 moles

c) 25cm3 = 0.025dm3

Moles = Concentration x Volume
= 0.1 x 0.025
= 0.0025 moles

d) 10cm3 - 0.010dm3

Moles = Concentration x Volume
= 0.2 x 0.010
= 0.002 moles

Hope this helped :)