The Wurtz reaction between methyl chloride and sodium metal in presence of dry ether can be written as :
2CH3Cl+2NaDry etherEthaneCH3—CH3+2NaCl⇒2 moles of sodium metal reacts to give 1 mole of ethane.
Also,
1 mole of Na metal =23g∴2 moles of Na metal =23×2=46g
Thus, 46g of sodium is required to prepare one mole of ethane from methyl chloride by Wurtz reaction