Question

What amount of Na2CO3 is dissolve in 250 ml water to prepare semi molar solution?☺

Answer 1

Answer:

12.875 g.

Explanation:

We get that the number of moles will be equal to:-

Moles equal to its concentration x volume (n=cv)

=0.5mol/dm3 x (250/1000)dm3

Which on solving we will get that.

=0.125mol.

Now, the gram molecular mass of the Na2CO3:-

( 23 x 2) + 12 + (16 x 3).

= 46 + 12 + 48

=106 (g/mol).

So, the mass which is needed for giving 0.125 moles of the Na2CO3 will be:-

moles= mass / molar mass

Hence, we get that the mass = moles X molar mass.

=0.125 x 106.

=12.875 g.