1) Two clear solutions are placed in separate beakers. The first solution has a pH = 4, and the pH of the second solution is unknown. If the two solutions are mixed and the resulting solution has a pH = 7, describe the second solution.

pH = 10

Explanation:

pH = -log [H⁺]

A solution that is pH = 4 has a [H⁺] = 1x10⁻⁴M

As the mixture of the two solutions is pH = 7 (Neutral). The second solution must contain the exact amount of OH⁻ to neutralize the H⁺ of the first solution. That is [OH⁻]  1x10⁻⁴

And as pOH = -log [OH⁻]

pOH = -log 1x10⁻⁴

pOH = 4

Also, pH = 14-pOH

pH of the second solution must be:

14 - 4

2fe + 3h2so4 -> fe2(so4)3 + 3h2

it is necessary to balance equations in order to get the proper amount of reactants as well as products in order not to make a miscalculation.

you cannot change the subscripts as that would change the substance itself. for instance, diatomic elements such as h2 only have the subscript two when a gas. another example would be so4, if you were to change the subscript, the element would no longer be sulfate.

we change the coefficients instead as that only changes the number of molecules rather than the substance itself.

hope this !