A synthesis reaction is a reaction in which two compounds come together to form one. In this case, if the product is lithium sulfide, the reactants will be lithium and sulfur. Lithium in its natural form is solid, and sulfur also has a solid-state. Lithium sulfide is also a solid compound. The synthesis reaction will be:
Now, we have to balance the equation. We have two atoms of Li on the products side and 1 atom of Li on the reactants side. So, we put the coefficient 2 in Li molecules.
Now, we have the balanced equation of the synthesis reaction of Lithium Sulfide