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

• Substance A.

Step-by-step explanation:

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

It is defined as:

`pH=\log (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.