which solution has the greatest number of hydroxide ions? baking soda, ph = 9 milk, ph = 6 tomato juice, ph…

Explanation:

Step1: Recall pH - pOH relationship

$pH + pOH=14$

Step2: Calculate pOH for each solution

For baking soda ($pH = 9$), $pOH=14 - 9=5$; for milk ($pH = 6$), $pOH=14 - 6 = 8$; for tomato juice ($pH = 3.5$), $pOH=14 - 3.5=10.5$; for vinegar ($pH = 2$), $pOH=14 - 2 = 12$.

Step3: Recall relationship between pOH and $[OH^-]$

The lower the pOH value, the higher the concentration of hydroxide ions $[OH^-]$. Since $[OH^-]=10^{-pOH}$, a lower pOH means a larger $[OH^-]$. Baking soda has the lowest pOH among the given solutions.

Answer:

baking soda, pH = 9