Question

Which of the following solutions has the largest concentration of solvated protons: (a) \(0.2 \mathrm{MLiOH}\), (b) \(0.2 \mathrm{M} \mathrm{HI}\), (c) \(1.0 \mathrm{M}\) methyl alcohol \(\left(\mathrm{CH}_{3} \mathrm{OH}\right)\) ? Explain.

Short answer

Of the given solutions, the 0.2 M HI solution has the largest concentration of solvated protons as it has a concentration of 0.2 M of H+ ions. This is because LiOH, being a strong base, does not release any H+ ions, and methyl alcohol, being a weak acid, has a significantly lower concentration of solvated protons compared to the HI solution.

Step-by-step solution

Evaluate the concentration of solvated protons in LiOH solution

As LiOH is a strong base and does not release any H+ ions upon dissociation, the concentration of solvated protons in this solution is simply 0.

Evaluate the concentration of solvated protons in HI solution

As HI is a strong acid, it will dissociate completely in water. The concentration of HI is 0.2 M, meaning 0.2 moles of HI will dissociate into 0.2 moles of H+ ions per liter of solution. So, the concentration of solvated protons in this solution is 0.2 M.

Estimate the concentration of solvated protons in methyl alcohol solution

Methyl alcohol, CH3OH, is a weak acid. It will only partially dissociate into H+ and CH3O- ions. As methyl alcohol is a very weak acid and its concentration is 1.0 M, we can assume that the concentration of solvated protons in this solution will be significantly lower than 1.0 M and lower than the concentration found in the HI solution.

Compare the concentrations of solvated protons in the solutions.

Comparing the three solutions, we find the following concentrations of solvated protons: (a) LiOH solution: 0 M (b) HI solution: 0.2 M (c) Methyl alcohol solution: < 0.2 M (estimated)

Conclusion

Of the given solutions, the 0.2 M HI solution has the largest concentration of solvated protons as it has a concentration of 0.2 M of H+ ions.

Key concepts

Solution Chemistry

When studying solution chemistry, we delve into the properties and behaviors of substances dissolved in a solvent. A key player in this field is the concentration of various species present in a solution. Think of a solution like a team, with each molecule or ion playing a specific role. The concentration tells us how many team members there are in a given volume. Measuring concentration, such as molarity (moles of solute per liter of solution), enables chemists to predict how substances will react with each other in a solution.

Solvated protons, which are basically hydrogen ions (H+) surrounded by a layer of water molecules, are no exception. Their concentration is crucial when considering the acid strength in water. The more solvated protons present, the greater the acidic strength. A perfect example from the exercise is comparing three different substances. For instance, hydroiodic acid (HI) has a high number of protons ready to hop into the role of increasing the solution's acidity, which makes it a great study example for strong acids in solution chemistry.

Acid-Base Dissociation

The concept of acid-base dissociation is a thrilling plot twist in the chemistry narrative. Acids and bases don't always reveal their true nature until they're in the right environment. When an acid dissolves in water, it can split up into ions, a process called dissociation. This is where our solvated protons come in - they are the result of acids giving away their H+ ions. If we think of acids as kind-hearted entities that donate to a cause, then the protons are their generous contributions to the solution's acidity.

Now, depending on the acid's morale - or scientifically speaking, its strength - it might give away all of its protons or only a few. Strong acids like our friend HI in the exercise, dissociate fully and release a full squad of protons, earning them a high concentration of solvated protons. Meanwhile, the weak acids like methyl alcohol are the shy ones, partially dissociating and contributing fewer protons to the solution.

Strong and Weak Electrolytes

Categorizing substances into strong and weak electrolytes is akin to separating athletes by stamina. Strong electrolytes, like powerful sprinters, go the distance and dissociate completely in solution, leaving no molecule unturned. This includes our all-star HI, which is adept at releasing protons with ease. On the other hand, weak electrolytes, akin to casual joggers, only partially dissociate, content with a more laid-back approach to separation into ions.

Strong electrolytes produce a high concentration of ions, leading to increased conductivity of the solution – think of it like an athletic track bustling with high-speed runners. In the exercise, the HI solution is the track star, sprinting ahead with a full 0.2 M of solvated protons. Weak electrolytes like methyl alcohol bring fewer ions to the race, hence the concentration of solvated protons is much less spirited. Understanding these distinctions helps chemists predict the electrical properties of a solution and the dynamics between the solutes involved.