Question

If 25.8 grams of BaO dissolve in enough water to make a 212-gram solution, what is the percent by mass of the solution?
A. 12.2% BaO
B. 8.92% BaO
C. 10.8% BaO
D. 8.22% BaO

Answer 1

The answer is A. 12.2% BaO

Below is the solution as to how the answer was generated:

Let:

25.8g = mass of solute

212g = mass solution

Equation:

% = (mass of solute / mass solution) x 100

Substitute the given values to the equation:

% = (25.8 / 212) x 100

% = 0.122 x 100

= 12.2%

Answer 2

Correct Answer: Option A i.e. 12.2 % BaO
.....................................................................................................................................

Reason: percent by mass is mathematically expressed as: 
% by mass = $\frac{\text{Weight of solute (g)}}{\text{Weight of solution (g)}}$ X 100

Given: weight of solute (BaO) = 25.8 g weight of solution = 212 g

∴, % by mass of the solution = $\frac{25.8X100}{212}$
                                              = 12.2 %

 Thus, percent by mass of BaO in solution is 12.2 %