Question

A student is investigating the pH of a substance. The pH of the unknown substance is 5.4. Which of the following substances is the unknown substance most likely to be? How do you know? Answer using a CER format using the above graphic organizer. Use evidence from the simulation in your response. Digitally complete, and then email a copy of the graphic organizer OR print and take a photo and email.
Substance A, which has a H3O+ concentration of 4x10^-6
Substance B, which has a H3O+ concentration of 6x10^-7
Substance C, which has a H3O+ concentration of 55
Substance D, which has a H3O+ concentration of 1.3x10^-1

Answer 1

Answer:

• Substance A.

Explanation:

pH is a measure of the concentration of H₃O⁺ ions in a solution.

It is defined as:

     $pH=\log \dfrac{1}{[H_3O^+]}=-\log [H_3O^+]$

For the given substances

Sustance        [H₃O⁺]         pH = - log [H₃O⁺]

                           M

    A                4×10⁻⁶         -log (4×10⁻⁶) = 5.4 ← answer

    B                6×10⁻⁷         -log (6×10⁻⁷) = 6.2

    C               error                      - - - - - -

    D               1.3×10⁻¹        -log (1.3×10⁻¹) = 0.89

Thus, the unknown substace most likely is A.