An ideal gas has a pressure of 2.5 atm, a volume of 1.0 l at a temperature of 30°c. how many molecules are there in this gas? (r = 8.31 j/mol ∙ k,1.00 atm = 101 kpa, na = 6.022 × 1023)

In the gas there are 6.02x10²² molecules

Explanation:

This is a problem to be solved by the Ideal Gas Law formula, which is this one:

Pressure . volume = n° moles . R . T° in K

The excersise presented R as 8.31 J/mol, but If i follow the others data, I'd rather use 0.082 L.atm / mol.K

Let's replace numbers:

2.5 atm . 1L = n° moles. 0.082L.atm / mol.K . 303K

(2.5 atm . 1L) / (0.082 mol.K/L.atm . 303K) = n° moles

0.100 moles = n

Now that we have the moles, we can use NA to calculate the total of molecules:

1 mol ___ has __ NA molecules

0.1 mol has ( 0.1 . 6.02x10²³) = 6.02x10²² molecules

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 !