Gas Concentration: ppm by Volume vs mg/L

In summary, ppm by volume and mg/L are two common units of measurement for gas concentration. Ppm by volume is used to measure the concentration of a gas in a gas mixture, while mg/L is used to measure the mass of a gas in a liquid solution. The accuracy of these units depends on the specific situation and it is important to use the appropriate unit for the gas and solution being measured. Other units such as ppb, ppt, and % vol can also be used to measure gas concentration, and in industrial settings, gas detectors and analyzers are commonly used to measure and monitor gas concentration in real-time.
  • #1
gunnar
39
0
a gas is x ppm by volume
Liquids are mg/L
but what about the gas?
 
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  • #2
ppm is a mass ratio -

ppm = parts per million = mg / kg = [itex]\mu[/itex]g/g

To get mole fraction, one has to divide by the appropriate molecular mass.
 
  • #3


Gas concentration is typically measured in parts per million (ppm) by volume, whereas liquids are measured in milligrams per liter (mg/L). This means that for a gas, the concentration is measured in terms of its volume in relation to the total volume of the mixture, while for a liquid, it is measured in terms of the mass of the substance in a given volume of the liquid.

For example, if a gas is 50 ppm by volume, it means that for every 1 million units of the mixture, 50 units are the specific gas. On the other hand, if a liquid has a concentration of 50 mg/L, it means that for every liter of the liquid, there are 50 milligrams of the substance.

It is important to note that ppm by volume and mg/L are not interchangeable units of measurement. They represent different ways of quantifying the concentration of a substance in a mixture. Additionally, the concentration of a gas can vary greatly depending on temperature and pressure, whereas the concentration of a liquid is not affected by these factors.

In summary, while liquids are measured in mg/L, gases are typically measured in ppm by volume. Both units are important for accurately determining the concentration of a substance in a mixture.
 

1. What is the difference between ppm by volume and mg/L for measuring gas concentration?

Ppm by volume (parts per million by volume) is a measure of the concentration of a gas in a mixture of gases. It represents the number of parts of a gas per million parts of the entire mixture by volume. Mg/L (milligrams per liter) is a measure of the mass of a gas in a liquid solution. It represents the number of milligrams of a gas per liter of the solution.

2. Which unit of measurement is more accurate for measuring gas concentration?

Both ppm by volume and mg/L are commonly used to measure gas concentration and can be accurate depending on the situation. Ppm by volume is more commonly used for gases in air or gas mixtures, while mg/L is more commonly used for gases dissolved in liquids. It is important to use the appropriate unit of measurement for the specific gas and solution being measured.

3. How do you convert ppm by volume to mg/L?

To convert ppm by volume to mg/L, you will need to know the molecular weight of the gas. You can then use the following formula: mg/L = (ppm by volume) x (molecular weight of gas) x (density of gas at standard temperature and pressure). It is important to note that the density of a gas can vary depending on temperature and pressure, so the conversion may not be exact.

4. Can gas concentration be measured in other units besides ppm by volume and mg/L?

Yes, there are other units that can be used to measure gas concentration, such as parts per billion (ppb), parts per trillion (ppt), and percentage by volume (% vol). The appropriate unit to use will depend on the concentration of the gas and the specific application.

5. How is gas concentration typically measured in industrial settings?

In industrial settings, gas concentration is often measured using instruments such as gas detectors or gas analyzers. These instruments can measure gas concentration in various units, including ppm by volume and mg/L, and provide real-time readings for monitoring purposes. They are commonly used in industries such as oil and gas, chemical production, and mining.

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