Answer:
Step-by-step explanation:
The equation for the reaction of lithium with water to produce lithium hydroxide and hydrogen gas is:
Li + H2O -> LiOH + H2
To balance this equation using the electron-transfer method, we first need to determine the oxidation states of each element in the reactants and products.
In Li, the oxidation state of lithium is +1. In H2O, the oxidation state of hydrogen is +1 and oxygen is -2.
In LiOH, the oxidation state of lithium is +1, oxygen is -2 and hydrogen is +1.
In H2, the oxidation state of hydrogen is +1.
It's clear that lithium loses 1 electron to become Li+ and hydrogen gains 1 electron to become H-.
So, we have to add an electron on the right side of the equation to balance the electrons.
Li + H2O -> LiOH + H2 + e-
Now, the number of electrons on both sides of the equation is the same and the equation is balanced.
Alternatively, we can use the oxidation number method, where we balance the charge of the reactant and product side of the equation. The sum of the oxidation numbers of all atoms on the reactant side must equal the sum of the oxidation numbers of all atoms on the products side. In this case, the oxidation state of lithium is +1, hydrogen is +1 and oxygen is -2.
Li + H2O -> LiOH + H2
+1 +1 -2 = +1 +1 +1 -2
The equation is already balanced with respect to oxidation numbers