Question

Question no.1

A solution of NaOH has concentration 1.2 M .
calculate the mass of NaOH in g/dm^3 in this solution.







Question no.2

A solution is prepared by dissolving 10g of haemoglobin in enough water to make up 1 dm^3 in volume.Calculate molarity of this solution . Molar mass haemoglobin is 6.51×10^4 g/moles.
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Answer 1

Answer:

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Answer 2

Answer No. 1

The mass of NaOH in g/$dm^{3}$  this solution is 0.02083.

Given:

The concentration of NaOH solution = 1.2M.

To Find:

The mass of NaOH in g/$dm^{3}$  in this solution =?

Solution:

We know that;

1  $dm^{3}$ = 1 Litre

Molecular mass of NaOH = 40.

Molarity is a term to measure the concentration of a solution.

Molarity is equal to the number of moles of the solute per litre of the solution.

Let, Volume of the solution is 'x' litres.

i.e., Molarity =  $\frac{No.OfMoles}{Volume(L)}$

      Molarity =  $\frac{\frac{mass(Grams)}{Molar mass} }{volume(L)}$

∴    x = $\frac{1}{(1.2)(40)}$   g/$dm^{3}$

∴    x = 20.83 $\frac{mg}{dm^{3} }$

Answer No. 2:

The Molarity of the solution of haemoglobin is 1.53 × $10^{-4}$ $\frac{mol}{Litre}$.

Given:

The mass of haemoglobin dissolved in water = 10 grams.

Volume of water = 1 Litre.

Molar mass of haemoglobin is = 6.51×10^4 g/moles.

​To Find:

The Molarity of the solution =?

Solution:

We have,

Molarity =  $\frac{No.OfMoles}{Volume(L)}$

Molarity =  $\frac{\frac{mass(Grams)}{Molar mass} }{volume(L)}$

Substituting the values, we get;

Thus, Molarity of the solution is equal to 1.53 × $10^{-4}$ $\frac{mol}{Litre}$.

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