Problem:
30 ml, 50% (v/v) HCl added into 70ml, 20% (v/v) HCl solution. Find % (v/v) of resultant solution.

Solution:

Step 1: Calculate the amount of HCl in each solution

Amount of HCl in 30 ml of 50% (v/v) HCl solution = 30 ml x 50/100 = 15 ml

Amount of HCl in 70 ml of 20% (v/v) HCl solution = 70 ml x 20/100 = 14 ml

Step 2: Calculate the total amount of HCl in the mixture

Total amount of HCl = 15 ml + 14 ml = 29 ml

Step 3: Calculate the total volume of the mixture

Total volume of the mixture = 30 ml + 70 ml = 100 ml

Step 4: Calculate the % (v/v) of HCl in the resultant solution

% (v/v) of HCl in the resultant solution = (total amount of HCl / total volume of the mixture) x 100

= (29 ml / 100 ml) x 100

= 29%

Therefore, the % (v/v) of HCl in the resultant solution is 29%.

Explanation:

In this problem, we are given two solutions of HCl with different concentrations (50% and 20%). We need to find the % (v/v) of HCl in the resultant solution after mixing these two solutions.

To solve this problem, we first need to calculate the amount of HCl in each solution using the given concentration and volume. Then, we can add these amounts of HCl to get the total amount of HCl in the mixture.

Next, we need to calculate the total volume of the mixture by adding the volumes of the two solutions. Finally, we can calculate the % (v/v) of HCl in the resultant solution by dividing the total amount of HCl by the total volume of the mixture and multiplying by 100.

Therefore, the % (v/v) of HCl in the resultant solution is 29%.

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