Question 2420c

Aug 8, 2016

The Kb determines if a compound is a weak base or a strong base. Also the determination of pH or POH can determine if s compound is a strong or weak base.

Explanation:

A strong base has a large number of basic ions OH- in solution. A weak base has a small percentage of basic ions OH - in solution.

Ph 8-10 are weak bases, Ph 11-14 are strong bases.

H+ + OH- = 14

in water H+ = ${10}^{-} 7$ and OH- = ${10}^{-} 7$

At Ph 13 for example H+ = ${10}^{-} 13$ while OH- =  10^-1

The total must always equal ${10}^{-} 14$

OH- ${10}^{-} 1$ means that 1/10 molecules is a OH- ion 10% of the solution that makes it a strong base.

pH 8 means that OH- = ${10}^{-} 8$

${10}^{-} 8$ = 1/00000000 of the solution are OH- ions. That makes it a weak base.

Aug 26, 2016

The ${K}_{b}$ determines if a compound is a weak base or a strong base.

Explanation:

A strong base dissociates completely in solution (has a K_b ≫ 1).

A weak base dissociates slightly in solution (has a K_b ≪ 1).

A base can be a strong base, even if it contributes only a few ions to the solution.

Thus, $\text{NaOH}$ is a strong base because it dissociates completely:

$\text{NaOH(aq)" → "Na"^+"(aq)" + "OH"^"-""(aq)}$

If you dissolve ${10}^{\text{-8" color(white)(l) "mol of NaOH}}$ in 1 L of water, it will contribute only ${10}^{\text{-8"color(white)(l) "mol}}$ of $\text{OH"^"-}$ ions, but that is 100 % of what it has to give.

$\text{NaOH}$ is a strong base. Its strength does not depend on its concentration.