Question

in the reaction mgcl2+2koh mg(oh)2 +2kci IF 1 MOLE MGCL2 IS added to 3 moles koh what is the limiting reagent

Answer 1

Answer: $MgCl_2$

Explanation:

$MgCl_2+2KOH\rightarrow Mg(OH)_2+2KCl$

According to stoichiometry,

1 mole of $MgCl_2$ reacts with 2 moles of $KOH$

Thus when 1 mole of $MgCl_2$ is added to 3 moles of $KOH$ , (3-2)moles= 1 mole of $KOH$ will remain unused.

Thus $MgCl_2$ is the limiting reagent as it decides the formation of products.

$KOH$ is excess reagent as it remains unused.

Answer 2

For 1 mole of MgCl2, it would require 2 moles of KOH. ( 1 : 2 mole ratio) 

Since you have 3 moles of KOH, it is in excess, and MgCl2 is the limiting reactant.