Which of the following statements about a carbonated cola beverage with a pH of 2.9 is true?
a. It has a relatively high concentration of hydrogen ions.
b. It has a relatively low concentration of hydrogen ions.
c. It has equal amounts of hydroxyl and hydrogen ions.
d. Cola is a buffered solution.

Verified step by step guidance

Recall that pH is a measure of the hydrogen ion concentration in a solution, defined by the formula \(\text{pH} = -\log_{10}[\mathrm{H}^+]\).

Understand that a lower pH value indicates a higher concentration of hydrogen ions, while a higher pH indicates a lower concentration of hydrogen ions.

Given the pH of the cola beverage is 2.9, recognize that this is an acidic pH (since it is less than 7), meaning the solution has a relatively high concentration of hydrogen ions.

Evaluate the options: (a) states a high concentration of hydrogen ions, (b) states a low concentration, (c) states equal amounts of hydroxyl and hydrogen ions (which would correspond to neutral pH 7), and (d) states that cola is buffered (which is generally not true for cola beverages).

Conclude that the correct understanding is that the cola beverage with pH 2.9 has a relatively high concentration of hydrogen ions, making option (a) true.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

pH and Hydrogen Ion Concentration

pH is a measure of the hydrogen ion (H⁺) concentration in a solution, with lower pH values indicating higher H⁺ concentrations. A pH of 2.9 means the solution is acidic and contains a relatively high concentration of hydrogen ions compared to neutral water (pH 7).

Acidic vs. Basic Solutions

Acidic solutions have pH values below 7 and contain more hydrogen ions than hydroxyl ions, while basic solutions have pH values above 7 with more hydroxyl ions. Neutral solutions have equal concentrations of hydrogen and hydroxyl ions, typically at pH 7.

Buffered Solutions

A buffered solution resists changes in pH when acids or bases are added, usually containing a weak acid and its conjugate base. Most carbonated beverages like cola are not buffered; their pH can change easily due to dissolved carbon dioxide and acids.

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