Approach: The quantity of heat produced is related to number of moles of reactant on the balanced chemical equation. So, first find out how many moles of sodium are in 0.705 g of sodium (use molar mass of Na, which is nothing but the atomic mass of Na in g/mol). Then according to the balanced equation, you need to calculated how much heat will be released using 2 moles of Na.
Moles of sodium =0.705g/23.0 g/mol = 0.031 mol
So if 0.031 mol Na releases 7330 J, then the 2 mol of Na would release....
[7330j/0.031] *[2 mol] = 4.73 x105 J or 473 kJ