The Notes: The strengths of acids and bases are measured by the concentration levels of Hydrogen or Hydroxide ions. If a solution is neutral, the...

Saturday, October 3, 2015

The strengths of acids and bases are measured by the concentration levels of Hydrogen or Hydroxide ions. If a solution is neutral, the...

The "concentration" of a substance is indicated by placing square brackets around the substance.

The concentration of $\displaystyle~{{H}}^{+}$ ions is written [ $\displaystyle~{{H}}^{+}$ ]

The concentration of $\displaystyle~{O}{{H}}^{{-{}}}$ ions is written [ $\displaystyle~{O}{{H}}^{{-{}}}$ ]

If [ $\displaystyle~{{H}}^{+}$ ] is greater than [ $\displaystyle~{O}{{H}}^{{-{}}}$ ], the substance is an acid. Acids have a pH that is less than 7.

If [ $\displaystyle~{O}{{H}}^{{-{}}}$ ] is greater than [ $\displaystyle~{{H}}^{+}$ ], the substance is a base. Bases have a pH that is greater than 7.

If [ $\displaystyle~{{H}}^{+}$ ] is equal to [ $\displaystyle~{O}{{H}}^{{-{}}}$ ], the substance is neutral. Neutral substances have a pH = 7.

Pure water is neutral. Therefore, [ $\displaystyle~{{H}}^{+}$ ] is equal [ $\displaystyle~{O}{{H}}^{{-{}}}$ ]. The ionization constant ( $\displaystyle~{K}_{{w}}$ ) is equal to 1.0 x $\displaystyle~{{10}}^{{-}}^{14}$ . $\displaystyle~{K}_{{w}}$ can been described by the following formula:

$\displaystyle~{K}_{{w}}$ = [ $\displaystyle~{{H}}^{+}$ ][ $\displaystyle~{O}{{H}}^{{-{}}}$ ] = 1.0 x $\displaystyle~{{10}}^{{-}}^{14}$

Since, the $\displaystyle~{{H}}^{+}$ and $\displaystyle~{O}{{H}}^{{-{}}}$ concentrations must be equal, [ $\displaystyle~{{H}}^{+}$ ] and [ $\displaystyle~{O}{{H}}^{{-{}}}$ ] must be equal to 1.0 x $\displaystyle~{{10}}^{{-}}^{7}$ .

Therefore, the answer is c.

The Notes

Saturday, October 3, 2015

The strengths of acids and bases are measured by the concentration levels of Hydrogen or Hydroxide ions. If a solution is neutral, the...

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