Question

Indicate whether each of the following statements is characteristic of an acid or a base: a. neutralizes acids b. produces \(\mathrm{OH}^{-}\) ions in water c. has a soapy feel d. turns litmus red

Short answer

a. Base, b. Base, c. Base, d. Acid

Step-by-step solution

Identify the characteristic of neutralizing acids

Bases neutralize acids. Acids react with bases to form water and a salt in a neutralization reaction.

Determine which produces \(\mathrm{OH}^{-}\) ions in water

Bases produce \(\mathrm{OH}^{-}\) ions in water. This is a defining characteristic of bases.

Recognize which has a soapy feel

Bases typically have a soapy or slippery feel to them when touched.

Identify the characteristic of turning litmus red

Acids turn blue litmus paper red. This is a common indicator test for acids.

Key concepts

neutralization reaction

Neutralization reactions are central to understanding acids and bases. When an acid and a base are mixed, they react to form water and a salt. This reaction happens because the hydrogen ions \(\text {H}^{+}\) from the acid combine with the hydroxide ions \(\text{OH}^{-}\) from the base. The resulting reaction can be summarized as:
\[ \text{H}^{+} + \text{OH}^{-} \rightarrow \text{H}_2 \text{O} \]
The product, water, is neutral, meaning it has a pH of 7. Neutralization is essentially the process by which the properties of an acid cancel out the properties of a base, and vice versa. This process is frequently used to mitigate the effects of acid spills and adjust pH levels in various chemical processes.
In summary, knowing how acids and bases neutralize each other can be crucial in chemistry, environmental science, and many industrial applications.

hydroxide ions

Hydroxide ions \(\text{OH}^{-}\) are a defining characteristic of bases. When bases dissolve in water, they release hydroxide ions, increasing the water's pH above 7. This is what makes solutions of bases feel slippery or soapy. An important formula to remember is:
\[ \text{Base} \rightarrow \text{OH}^{-} + \text{Cation} \]
Bases like sodium hydroxide \(\text{NaOH}\) and potassium hydroxide \(\text{KOH}\) release a significant number of \(\text{OH}^{-}\) ions into the water. These ions are negatively charged and can neutralize positively charged hydrogen ions from acids. This neutralizing effect is precisely why bases are used to treat acidic conditions.
Understanding hydroxide ions helps explain why bases behave the way they do in different chemical reactions, playing a critical role in various applications and reactions.

litmus test

The litmus test helps identify whether a substance is an acid or a base. Litmus paper is soaked in a dye obtained from lichen. When placed in a solution, acids and bases cause the paper to change color:

• Acids turn blue litmus paper red.
• Bases turn red litmus paper blue.

Using litmus paper is a quick and straightforward method for determining the pH nature of a solution. It provides immediate visual feedback. This simple test is often taught in introductory chemistry classes and is also used in laboratory settings. Despite its simplicity, it is incredibly useful for rapidly screening the substance's chemical properties.
For practical purposes, always have litmus paper in your toolkit whenever you need to test for the presence of acids or bases quickly.

soapy feel

The soapy or slippery feel associated with bases is a tangible way to identify them. This occurs because bases react with the oils in your skin to form soap. It's a common physical property for many basic solutions. Examples of substances with a soapy feel include many household cleaning agents, such as:

• Sodium hydroxide (lye)
• Ammonia solution

These substances are effective in cleaning because they can react with fats and oils, breaking them down into soaps that rinse away with water. This reaction and feel are more than just a curious property; they also underline why it is crucial to handle bases carefully. Always wear gloves when dealing with strong bases to avoid this slippery sensation and protect your skin.
Remember, recognizing the soapy feel is not just about identifying bases but understanding their practical applications and the necessary safety precautions.