An open flask sitting in a lab refrigerator looks empty, but it is actually filled with a mixture of gases called air. If the flask volume is 2.00 L, and the air is at standard temperature and pressure, how many gaseous molecules does the flask contain?

molecules are there in the flask

Explanation:

According to the ideal gas equation:

P = Pressure of the gas = 1 atm    

V= Volume of the gas = 2.00 L

T= Temperature of the gas = 273 K    

R= Gas constant = 0.0821 atmL/K mol

n= moles of gas

According to avogadro's law, 1 mole of every substance occupies 22.4 L at STP and contains avogadro's number of particles.

1 mole of gaseous air contains =   molecules

11.2 moles of gaseous air contains =   molecules

gaseous molecules are contained in the flask.

2fe + 3h2so4 -> fe2(so4)3 + 3h2

it is necessary to balance equations in order to get the proper amount of reactants as well as products in order not to make a miscalculation.

you cannot change the subscripts as that would change the substance itself. for instance, diatomic elements such as h2 only have the subscript two when a gas. another example would be so4, if you were to change the subscript, the element would no longer be sulfate.

we change the coefficients instead as that only changes the number of molecules rather than the substance itself.

hope this !