Question

During an experiment the students were asked to prepare a
30%(Mass/Mass) solution of sugar in water. Ramesh dissolved 30g of
sugar in 100g of water while Sumedh prepared it by dissolving 30g of
sugar in water to make 100g of the solution.
a) Are the two solutions of the same concentration?
b) Compare the mass % of the two solutions.​

Answer 1

Given:

Ramesh uses sugar (solute) = 30g

Mass of water Ramesh takes (solvent) = 100g

Sumedh uses sugar (solute) = 30g

Sumedh makes a solution of mass = 100g

To Find:

(a)Concentration of both prepared solutions are same or not.

(b)Mass % of the two solutions.

Solution:

Required mass % of the solution = 30%

Mass percentage can be calculate as

$\bold{mass\%=\frac{Mass\hspace{1mm} of\hspace{1mm} solute}{Mass\hspace{1mm} of\hspace{1mm} solution}\times 100}$

Here, Mass of solution = mass of solute + mass of solvent

Now, for Ramesh's case:

Mass % of Ramesh's solution = $\frac{30}{100+30}\times 100 = \frac{300}{13}=23.07\%$

And for Sumedh's case:

Mass % of Sumedh's solution = $\frac{30}{100}\times 100 = 30\%$

∴Mass % of Sumedh's solution > Mass % of Ramesh's solution

∴ From the above calculations we can conclude that,

(a) The concentration of two solutions are not same.

(b) Mass percentage of Sumedh's solution is accurate, which is also greater than the mass percentage of Ramesh's solution.