How many molecules of nitrogen dioxide gas (NO2) are present in 15 liters of the gas at STP?

4.031×

Explanation:

You first need to calculate the number moles of NO2.  To do this use PV=nRT

STP stands for standard temperature and pressure which is 0 degrees C and 1 atm.

due to that:

P = 1 atm

V = 15 L

R = 0.08206 L*atm/mol*K

T = 273 K

n = unknown moles

solve for n to make the equation n=PV/RT

n=(1atm*15L)/(0.08206 Latm/molK*273K)

n=0.6696 mol of NO2

Then to find the number of molecules we use Avogadro's number which tells us the number of molecules per mol of a molecule or atom.

Avogadro's number is  6.02x10^23 molecules/mol

number of molecules = 0.6696mol × 6.02x10^23 molecules/mol

number of molecules = 4.031×10^23 molecules of NO2

Let me know if anything is not clear or if you get something else in the comments so that we can work it out.

the leaf is an organ of a typical plant, and the main functions are to complete photosynthesis and allow the plant to exchange gas, just like how we have the respiratory system. leaves have the stomata, which collects maintains co2 and o2 levels. this is necessary for cell metabolism. the leaf also collects sunlight using chloroplasts. succinctly, leaves own a pivotal role in sustaining plant life.