Question

Predict the products and write a balanced equation. For each part express your answer as a chemical equation and identify all of the phases in your answer.

A.) Decomposition: LiCl(s)-->__+__

B.) Combination: Ba(s) + Cl2(g)-->___

C.) Combination: NO(g) + O2(g)-->___

D.) Double Replacement: NiCl2(aq) + NaOH(aq)-->___+___

Please show how exactly how to balance each equation. I am having a hard time coming up with the correct answer, so if the steps could be shown I would appreciate it.

Answer 1

see you just have to know what is the oxidation state of the atom and their corresponding state as atom or molecule

for eg: Cl- has oxidation state of -1 and it's neutral state(ground state) = Cl₂

thus now looking as the equations

A) LiCl is made from Li atom and Cl₂ molecule

thus on decomposition

2 LiCl----> 2Li + Cl₂ ( as 1 Li+ will require 1 Cl- and since Cl2 is present only as Cl2 we have to take 2 moles of LiCl and get 2 moles of Li)

now similarly

B) Ba has oxidation state of +2 thus it willcombine with 2 Cl- or 1Cl₂ molecule

hence

Ba + Cl₂ -----> BaCl₂

C)

like i said you should know what the product is gonna be

so the expected product = NO₂

hence

NO + O₂ ----> NO₂

just look at No. of oxygens in reactant , we have 1 from NO and 2 from O₂ to give 2 in NO₂ , if we multiply NO by 2 and we will get 2 molesof NO₂

(which now results in balance in no. of oxygen atom in reactants and in produtcs)

D)

NaOH will combine with NiCl₂ to form NaCl , since we have 2 Cl- in NiCl2...thus we should also have 2 Cl- in product that is NaCl , thus we will have 2 moles of NaCl ...now that we have 2 moels of Na+ in NaCl as product we need to have 2 moles of Na+ in reactant as well as 2 moles of NaOH

hence

NiCl₂ + 2NaOH ----> Ni(OH)₂ + 2NaCl

we can see since we alrady nabalnce Na+ and Cl- ...Ni 2+ and OH- are balanced as well ..because it's a double displacement reaction