Question

select the correct answer. a solution has a ph of 4.20. using the relationship between ph and poh, what is the concentration of oh⁻? a. 9.9×10⁻¹ m b. 6.2×10⁻¹ m c. 6.3×10⁻⁵ m d. 6.7×10⁻⁶ m e. 1.6×10⁻¹⁰ m

Explanation:

Step1: Calculate pOH

We know that pH + pOH = 14. Given pH = 4.20, then pOH=14 - 4.20 = 9.80.

Step2: Find [OH⁻] concentration

The formula for pOH is pOH = -log[OH⁻]. So, [OH⁻]=10⁻ᵖᴼᴴ. Substituting pOH = 9.80, we get [OH⁻]=10⁻⁹.⁸⁰.
Using the property of exponents, 10⁻⁹.⁸⁰ = 1.58×10⁻¹⁰≈1.6×10⁻¹⁰ M.

Answer:

E. 1.6×10⁻¹⁰ M