How would I find the STP for N2,He, H2O?
(concentration in air at STP)
You don't have enough information to make sense. STP doesn't depend upon the gas; it is 1 atm pressure and 273 K for temperature for ANY gas.
The question just says:
Which of the following has the highest conentration in air at STP?
a)He
b)H2O
c)CO2
d)N2
e)O2
the answer was N2
but I don't know how to get that answer
You look it up in a table. N2 is about 79%, O2 about 20%, He, H2O, and CO2 lesser amounts making up the rest. Here is a site that will give you the information.
http://mistupid.com/chemistry/aircomp.htm
To find the standard temperature and pressure (STP) for a particular substance, such as N2 (nitrogen), He (helium), and H2O (water), you need to understand the concept of STP and the conditions at which it is defined.
STP is defined as a temperature of 0 degrees Celsius (273.15 Kelvin) and a pressure of 1 atmosphere (atm), which is equivalent to 101.325 kilopascals (kPa). It is a standard reference point commonly used in chemistry and physics.
To determine the concentration of a substance in air at STP, you would need to know the composition of air and the partial pressure of the substance you are interested in. The composition of air consists mainly of nitrogen (N2), oxygen (O2), and traces of other gases like helium (He).
However, it is important to note that the concentration of gases in air is expressed in terms of volume percent rather than more common concentration units like molarity. In other words, the concentration of a gas in air is given as a fraction of the total volume of air.
In order to find the concentration of N2, He, and H2O in air at STP, you would need to look up their respective volume percent values for the composition of air. The volume percent for N2 is approximately 78%, for O2 is approximately 21%, and for traces of other gases, including He and H2O, is less than 1%.
You can refer to reliable sources such as textbooks, scientific databases, or even online resources that provide information about the composition of air and the volume percent of gases at STP. This information can assist you in determining the approximate concentrations of N2, He, and H2O in air at STP.
Keep in mind that the concentrations of these gases may vary slightly depending on factors such as location, elevation, and environmental conditions.