Chemical formula for iron (l) selenide

the reactant in the equation give in 2na and cl2.

answer:   31.55 g

explanation:

- the mass number of fluoride atom (f) = 18.99 g/mol, so mass number of         fluorine gas (f2) = 37.98 g/mol.

-   1 mole of (f2) [which has 37.98 g/mol] contains avogadro’s number of molecules (6.02×10^23 molecules),

    so   1 mole of (f2) with 37.98 g/mol →   6.02×10^23 molecules.

- using cross multiplication,  

                                37.98 g/mol of (f2)         →       6.02 ×10^23 molecules

                                                        ?               →         5.00 ×10^23 molecules

hence the mass of 5.00×10^23 molecules of f2 = (37.98 × 5.00 × 10^23) / 6.02 ×10^23 = 31.55 g..

ability to react with oxygen