To solve this problem, we need to use stoichiometry and the balanced chemical equation for the reaction between MgCl2 and MgS:
MgCl2 + MgS → 2Mg + 2Cl + S
From the equation, we can see that 1 mole of MgCl2 reacts with 1 mole of MgS to produce 2 moles of Mg. Therefore, we need to find the number of moles of MgCl2 that react with 6 moles of MgS.
6 moles of MgS is equal to 6 moles MgS x (1 mole MgCl2/1 mole MgS) = 6 moles MgCl2
Now, we can use the molar mass of MgCl2 to convert moles of MgCl2 to grams:
6 moles MgCl2 x 95.21 g/mol = 571.26 g MgCl2
Therefore, 571.26 grams of MgCl2 were used to produce 6 moles of MgS.