`suppose you have a sample that has a low ph (acidic). what would be true of the [oh-]?

A sample that has low pH, will have a [OH⁻] < 1x10⁻⁷

Explanation:

Kw = 1x10⁻¹⁴

[H₃O⁺] = 1x10⁻⁷

[OH⁻] = 1x10⁻⁷

If pH is very low, [H₃O⁺] > 1x10⁻⁷

For example,  [H₃O⁺] = 1x10⁻³ M

- log [H₃O⁺]  = pH

- log 1x10⁻³ M = pH = 3

[OH⁻] will be < 1x10⁻⁷

For the example we made before

pH = 3

pOH = 14 - pH → 11

10^-pOH = [OH⁻]

10⁻¹¹ = 1x10⁻¹¹