2. Compare and Contrast A teacher asks you to use litmus strips to test the pH of three unknown substances. Substance 1 has a pH of 3 , and Substance 2 has a pH of 5 . A third substance is a powder When mixed with some water, it has a pH of 11 . Identify each substance as an acid or a base, then compare and contrast the properties of the three substances.

To identify each substance based on their pH values: 1. **Substance 1 (pH 3)**: This substance is acidic. Acids have a pH less than 7, and a pH of 3 indicates a relatively strong acid. 2. **Substance 2 (pH 5)**: This substance is also acidic, but it is a weaker acid compared to Substance 1. A pH of 5 is still below 7, indicating acidity, but it is less acidic than Substance 1. 3. **Substance 3 (pH 11)**: This substance is basic (or alkaline). Bases have a pH greater than 7, and a pH of 11 indicates a moderately strong base. ### Comparison of Properties: **1. Acidity vs. Basicity:** - **Substance 1 and Substance 2**: Both are acids, with Substance 1 being a stronger acid (pH 3) and Substance 2 being a weaker acid (pH 5). They can donate protons (H⁺ ions) in solution. - **Substance 3**: This is a base, which means it can accept protons or donate hydroxide ions (OH⁻) in solution. **2. pH Scale:** - The pH scale ranges from 0 to 14, where values below 7 indicate acidity, 7 is neutral, and values above 7 indicate basicity. - Substance 1 (pH 3) and Substance 2 (pH 5) are both on the acidic side of the scale, while Substance 3 (pH 11) is on the basic side. **3. Strength of Acids and Bases:** - **Substance 1**: Being a strong acid, it is likely to have a more pronounced effect on indicators and can react vigorously with bases. - **Substance 2**: As a weaker acid, it may have a milder effect on indicators and may not react as vigorously with bases compared to Substance 1. - **Substance 3**: As a base, it can neutralize acids, and its higher pH indicates a stronger basicity compared to the acidity of the other two substances. **4. Potential Reactions:** - **Substance 1 and Substance 2**: Both can react with bases to form water and a salt, demonstrating neutralization reactions. - **Substance 3**: This can react with both acids (Substance 1 and Substance 2) to neutralize them, producing water and salts. ### Summary: In summary, Substance 1 and Substance 2 are acids with pH values of 3 and 5, respectively, while Substance 3 is a base with a pH of 11. The two acids differ in strength, with Substance 1 being stronger than Substance 2. The base (Substance 3) can neutralize the acids, demonstrating the contrasting properties of acids and bases in terms of pH, reactivity, and strength.