Answer:
6.1133*10²¹ molecules of gas are in the sample.
Step-by-step explanation:
Ideal gases are a simplification of real gases that is done to study them more easily. It is considered to be formed by point particles, do not interact with each other and move randomly. It is also considered that the molecules of an ideal gas, in themselves, do not occupy any volume.
The pressure, P, the temperature, T, and the volume, V, of an ideal gas, are related by a simple formula called the ideal gas law:
P*V = n*R*T
where P is the gas pressure, V is the volume that occupies, T is its temperature, R is the ideal gas constant, and n is the number of moles of the gas. The universal constant of ideal gases R has the same value for all gaseous substances. The numerical value of R will depend on the units in which the other properties are worked.
So to calculate the amount of gas molecules that are in the sample you must first calculate the amount of moles of the gas using the previous ideal gas law:
where:
- P=0.973 atm
- V=250 mL=0.250 L (1 L=1000 mL)
- T= 19 °C=292,15 °K (0°C=273.15°K)
Replacing:
Resolving:
n≅0.01015 mol
On the other hand, the Avogadro Number or Avogadro Constant is called the number of particles that constitute a substance (usually atoms or molecules) and that can be found in the amount of one mole of that substance. Its value is 6.023 * 10²³ particles per mole.
Then, applying rule of three it is possible to calculate the amount of molecules present in the sample: if in one mole there are 6.023*10²³ molecules, in 0.01015 moles how many molecules will there be?
number of molecules≅6.1133*10²¹
6.1133*10²¹ molecules of gas are in the sample.