Question

How many atoms are in one cm3 of H2 gas at STP?

Answer 1

Answer: 5 x
`10^(19)` (atoms)

Step-by-step explanation:

According to Avogadro's law, at STP,

number of particles(atoms) =
`6.022 * 10^(23) mol^(-1)` * n

in which n is number of mol

Using Ideal Gas Law:

PV = nRT,

n = PV/RT

(Plug in values wrt STP)

=
`((1)(0.001)(atm * L))/((0.08206)(293)((L*atm)/(mol*K)))\\`

(Put it in the calculator,)

= 4.159 x
`10^(-5)` mol
`H_(2)`

Getting back to our Avogadro's law, substitute:

number of particles(atoms) =
`6.022 * 10^(23) mol^(-1)` * (4.159 x
`10^(-5)` mol
`H_(2)`)

= 2.5 x
`10^(19)`
`H_(2)`,

since there are 2 atoms in each
`H_(2)` particle, multiply our answer by 2 and we get:

5 x
`10^(19)` (particles)