In chemistry class, 6 liters of a 4% sliver iodide solution must be mixed with a 10% solution to get a 6% solution How many liters of the 10% solution is needed?

Let's focus on how much silver iodide we have and how much we obtain.

6 liters of a 4% solution constitutes 6 (0.04) liters of silver iodide:

0.24 liter. Let x be the number of liters of the 10% solution. The amount of silver iodide in that is 0.10 (x).

Adding together these two volumes of silver iodide:

0.24 liter + 0.10x = 0.06 (6 + x) liters

Then 0.24 + 0.10x = 0.36 + 0.06x

Simplifying, 0.04x = 0.12. Dividing both sides by 0.04, x = 0.12/0.04 = 3

3 liters of the 10% solution are needed in order to end up with a 6% solution of silver iodide.

Check: 0.04 (6) + 0.10 (3) = ? 0.06 (6+3)

0.54 = ? = 0.06 (9)

0.54 = ? = 0.54 Yes. So, our result is correct.