To calculate the number of grams of KCl produced from 4 mol of KOH, we need to use the stoichiometry of the balanced chemical equation provided:

MgCl2 + 2KOH → Mg(OH)2 + 2KCl

From this equation, we can see that 2 moles of KOH are required to produce 2 moles of KCl. Therefore, 4 moles of KOH will produce 4 moles of KCl.

The molar mass of KCl is approximately 74.55 g/mol. Therefore, 4 moles of KCl is equivalent to:

4 mol KCl × 74.55 g/mol = 298.2 g KCl

Therefore, approximately 298.2 grams of KCl would be produced from 4 mol of KOH.