leanred some new stuff but dn't understand them...help?

Question

1. If the concentration of oxygen in water is 8ppm, what mass of oxygen is present in 1L of water?
2. A 10% W/V salt solution is used for making pickles. What mass of salt is presnt in 750mL of this solution? (what is the formula i should use!!?!)
can someone explain to me about the ppm (parts per million)?

Answer 1

1 l of water almost weighs 1 kg

1 kg = 1000 g = 10^6 mg

Thus mass of O2 = 8 mg

2) In 1000 ml, 10 g are present

So, in 750 ml 7.5 g are present.

Answer 2

ppm is basically the same thing as %, except where % is parts per hundred, ppm is out of a million. Let's say I have 1 kg of some stuff, and I'm told that the concentration of a certain compound is 5 ppm. That means that (5/1,000,000) * 1 kg or 5 mg of it is my compound.

Answer 3

ppm means (in 1 L for examples) mg/L.

so if u have 8ppm it means that u have 8 mg of O2 in 1 L

2 10% W/V means that in 100ml u gotta 10g of salt.
so u can relate 750 to 10% in that way:

10:100=x:750

so x= 75g