In a certain experiment a student finds that the \(\mathrm{pHs}\) of \(0.10 M\) solutions of three potassium salts \(K X, K Y\) and \(\mathrm{KZ}\) are 7.0,9.0 , and 11.0 , respectively. Arrange the acids HX, HY, and HZ in order of increasing acid strength.

Understanding the pH scale is crucial for grasping the concepts of acid and base strength. The pH scale is a numeric scale used to specify the acidity or basicity of an aqueous solution. It typically runs from 0 to 14, with 7 being neutral, values below 7 indicating acidity, and those above 7 indicating basicity.

The pH scale is logarithmic, meaning each whole pH value below 7 is ten times more acidic than the next higher value. For instance, a substance with a pH of 4 is ten times more acidic than one with a pH of 5. This is important in the context of the provided exercise as it directly relates to the acid strength of the compounds in question.

Acid-base chemistry is a foundational pillar of chemical sciences and touches upon the reactivity and properties of acids and bases. Acids are substances that can donate a proton (H+) in a reaction, while bases can accept a proton. The strength of an acid is measured by its ability to donate protons. A strong acid will easily give up its proton, while a weak acid will not.

In the exercise, we see that each potassium salt solution has a different pH, indicating different degrees of acidity or basicity once dissociated in water. Potassium salts usually dissociate into K+ ions and their respective anions, which come from the original acids HX, HY, and HZ. The pH of the solution gives insight into the proton-donating tendency of the original acids, thus helping to classify them by strength.

Molarity is a measure of the concentration of a solute in a solution and is defined as the number of moles of solute per liter of solution. In chemistry, it is denoted by the symbol 'M' and is used because the reaction rates, as well as the reactant-product relations, are dependent on the concentration of the reactants.

The exercise mentions that the solutions of potassium salts have a concentration of 0.10 M, which indicates that in every liter of solution, there is 0.10 moles of the potassium salt dissolved. Identical molarities are key for comparing the pH of different solutions, as they ensure that the pH difference is due to the acid strength alone and not due to concentration differences.