A solution of 100.0 mL of 0.200 M KOH is mixed with a solution of 200.0 mL of 0.150 M NiSO4. We are supposed to write the balanced chemical equation for the reaction, and I found that their are 2.00 moles KOH in 100 mL and .03 moles nickel sulfate in 200 mL. From there, what should I do- I am supposed to write a balanced chemical equation?

A balanced chemical equation is an equation where we write a reaction in which the number of atoms is equal on both reactant and product sides. We do not include the concentration which is given in the question. Example:

`BaCl2 + Na2SO4 -> BaSO4 + NaCl`

Here we see that on the reactant side, there is 1 Ba atom, 2 CL atoms, 2 Na atoms, 1 S atom and 4 O atoms. While on the products side we have, 1 Ba atoms, 1 S atom, 4 O atoms, 1 Na atom and 1 Cl atom.

Hence, Na and Cl are not balanced. To balance any atom, we put the required coefficient before the molecule having unbalanced atoms. Here, we need 2 Na and 2 CL atoms on product side. So we put a 2 before NaCl on product side and balanced the reaction.

`BaCl2 + Na2SO4 -> BaSO4 + 2 NaCl`

Next, we need to identify the type of reaction to form the products. The reaction in our equation seems to be precipitation reaction, a type of double displacement reaction in which two soluble compounds form a solid or precipitate. Example:

` ` `BaCl2 + Na2SO4 -> BaSO4 + 2 NaCl`

A balanced equation also includes the states of matter of molecules, whether they are solid, liquid, gas, or aqueous. We can find out the state of matter by using solubility rules( link attached). Here, BaCl2, Na2SO4 and NaCl are aqueous or soluble so we use (aq) state for them while BaSO3 is the precipitate or solid so we use (s) for it.

`BaCl2 (aq) + Na2SO4(aq) -> BaSO4(s) + 2 NaCl(aq)`