# Converting ppm to mg/L

## Homework Statement

A is a stable powder
B is water
C is the product of the powder being in contact with water.

A is soluble in substance B and for every gram of A 10% is C.

For a concentration of 0.5ppm of C in twenty liters of water how many grams of A do you need?

## The Attempt at a Solution

I went on the assumption that ppm=mg/l.
So 0.5ppm=0.5mg/l, and I would need 10mg for the twenty liters
Which means that I would need 100mg of A.

Is this correct?

## The Attempt at a Solution

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Borek
Mentor
I would need 100mg of A.

Is this correct?
That would be my answer as well, although I find the wording of the question confusing.

Thanks for the confirmation, I'm just replying to say that 100mg was indeed the correct answer.

If you don't mind me asking, how did the wording confuse you?

Borek
Mentor
If 0.1g of A reacted with water, what is mass of the product? Again 0.1g? Not impossible, but counterintuitive, at least to me.