Question

Pehal and Ishaan were making 100g sugar solutions with concentration by mass 20% and 50% respectively.Pehal added 20g of sugar in her solution whereas Ishaan evaporated 20g of water from his solution.Now,the two solutions were mixed to form a final solution.The concentration by mass of final solution is ?????? How??????

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Answer 1

hey mate see the attachment for your answer

Answer 2

Answer: The concentration by mass of final solution is 45%.

Solution:

• In case of Pehal solution

She prepared 20% sugar solution in which she added 20 grams of sugar more which means;

Total mass of sugar in her solution = 20 + 20 =40 grams.....(1)

Total mass of water = 80 grams

Total mass of the solution after adding 20 grams of sugar = 40+80 = 120 grams.        ...(2)                                      

• In case of Ishaan solution

He prepared the 50% sugar solution from which he evaporated the 20ngrams of water.

Total mass of sugar in his solution = 50 grams  ...(3)

Total mass of water before evaporation = 50 grams

Total mass of water after evaporation = 50-20 = 30 grams

Total mass of the solution after evaporating 20 grams of water = 50+30 = 80 grams ...(4)

• When two solutions mixed together

Total Mass of sugar in resulting solution: 40 + 50= 90 grams  (from 1 and 3)

Total Mass of water in resulting solution: 120 + 80 = 200 grams   (from 2 and 4)

The mass concentration will be given as :

$\text{mass \%}=\frac{\text{total mass of sugar}}{{total mass of final solution}}\times 100$ ...(5)

On substituing the value in equation (5)

$\text{mass \%}=\frac{90}{200}\times 100= 45\%$

The concentration by mass of final solution is 45%.