Parts per million (ppm)

[DisaFear]

Hi,

Can someone explain ppm to me thoroughly? I just don't get it. The Heinemann Chemistry book doesn't have many useful examples, as far as i've seen. Looked it up on the Internet too, and used the search feature on this forum, haven't found anything too useful, example wise. Providing examples and some conversions will really help.

What is 1000 ppm CaCl2? 1000 parts of 1000000 waitwhathappenedhere?



Cheers

[luken93]

Parts per million = milligrams/L or micrograms/gram

Our drinking water is treated with chlorine to kill bacteria. Too much chlorine
is dangerous, and too little will not kill the bacteria. A safe amount is about
1 part per million (ppm), or 1 microgram of chlorine in each gram of solution.
(A microgram, μg, is 10–6 g, or 0.000 001 g.)

[RobM8]

ppm = parts per million

I think about it as similar to a percentage.
The similarity being that percentage is out of 100 parts, ppm is just out of 1,000,000 parts.

If the concentration of iron in a rock (mad example) is 5% by weight, there will be 5g of iron in 100g of the rock, 10g of iron in 200g of the rock ... so on
If the concentration of the iron in the rock was 5 ppm by weight, there will be 5g in every million grams
i.e 5g of iron in 1,000,000g (1,000,000 = 1Mg), 10g of iron in 2Mg, 15g in 3Mg ... so on

luken93's post pretty much summed it up though.

In addition:

No one exactly mentioned how water comes in this. We assume a density of 1L of water = 1000g. With this knowledge, we can convert a w/w ppm to a w/v concentration.

It is like three posts down but I guarantee a lot of people will not read it and will ask a question about it.

[DisaFear]

Hmm...I guess that works

So in 1000 ppm of CaCl2, what is the conc. of the Cl?
How is molarity converted to ppm? (sorry, lazy)

[pi]

Hmm...I guess that works

So in 1000 ppm of CaCl2, what is the conc. of the Cl?
How is molarity converted to ppm? (sorry, lazy)

Yep, so lazy DisaFear...

(lol, wasn't this part of a M/C question in our SAC? Easiest way was to convert them all to g/L and then go from there)

1000 ppm
= 1 g / L
= (1/M) / L
= n / L
Times two, because there are 2 moles of Cl- in CaCl2

[Mao]

No one exactly mentioned how water comes in this. We assume a density of 1L of water = 1000g. With this knowledge, we can convert a w/w ppm to a w/v concentration.

1 ppm of CaCl2 (for example)

This means:

1 g of CaCl2 per 1,000,000 g of water
0.001g of CaCl2 per 1000g of water
0.001g of CaCl2 per 1L of water
1mg/L of CaCl2

(and so on)

[VivaTequila]

ppm = parts per million

I think about it as similar to a percentage.
The similarity being that percentage is out of 100 parts, ppm is just out of 1,000,000 parts.

If the concentration of iron in a rock (mad example) is 5% by weight, there will be 5g of iron in 100g of the rock, 10g of iron in 200g of the rock ... so on
If the concentration of the iron in the rock was 5 ppm by weight, there will be 5g in every million grams
i.e 5g of iron in 1,000,000g (1,000,000 = 1Mg), 10g of iron in 2Mg, 15g in 3Mg ... so on

luken93's post pretty much summed it up though.

this explained it nicely