Is this multiple choice?<span />
1 mole ----------- 22.4 L ( at STP )
3.5 mols --------- ?
V = 3.5 x 22.4 / 1
V = 78.4 L
hope this helps!
Mass of molecule (g) = Mr of substance over avarogado constant
Does it is a complete qwestion? It
is not clearef