Question

Are each of the following examples acidic, basic, or neutral? a. rain, $\mathrm{pH}5.2$ b. tears, $\mathrm{pH}7.5$ c. tea, $\mathrm{pH}3.8$ d. cola, $\mathrm{pH}2.5$ e. photo developer, $\mathrm{pH}12.0$

Short answer

Rain: acidic, Tears: basic, Tea: acidic, Cola: acidic, Photo developer: basic.

Step-by-step solution

Understand pH Scale

The pH scale ranges from 0 to 14. A pH less than 7 indicates acidity, a pH of 7 is neutral, and a pH greater than 7 indicates basicity.

Analyze pH of Rain

Rain has a pH of 5.2. Since 5.2 is less than 7, rain is acidic.

Analyze pH of Tears

Tears have a pH of 7.5. Since 7.5 is greater than 7, tears are basic.

Analyze pH of Tea

Tea has a pH of 3.8. Since 3.8 is less than 7, tea is acidic.

Analyze pH of Cola

Cola has a pH of 2.5. Since 2.5 is less than 7, cola is acidic.

Analyze pH of Photo Developer

Photo developer has a pH of 12.0. Since 12.0 is greater than 7, photo developer is basic.

Key concepts

acidic solutions

An acidic solution is a liquid with a pH level less than 7. The pH scale ranges from 0 to 14, and anything below 7 is considered acidic.
Here's how it works:

• The lower the pH, the more acidic the solution.
• Common examples include lemon juice, which has a pH of 2, and stomach acid, with a pH around 1.5.
• Acids have more hydrogen ions (H⁺) in them, making them capable of donating these ions to other substances.

In our example:
a. Rain, with a pH of 5.2, is acidic.
c. Tea, with a pH of 3.8, is acidic.
d. Cola, with a pH of 2.5, is also acidic.
Understanding acidity helps in various fields, including food industry, medicine, and environmental science.

basic solutions

A basic solution has a pH level greater than 7. These solutions are also known as alkaline.
Here's what you need to know:

• The higher the pH, the more basic the solution.
• Common examples include baking soda solution, which usually has a pH of around 9, and household bleach, with a pH around 12.
• Basic solutions have more hydroxide ions (OH^-), which can accept hydrogen ions from acids.

In our examples:
b. Tears, with a pH of 7.5, are basic.
e. Photo developer, with a pH of 12.0, is also basic.
Basic solutions are crucial in various processes such as cleaning, manufacturing, and even in some biological systems.

neutral solutions

A neutral solution has a pH of exactly 7, which is neither acidic nor basic.
Here's what you should know:

• The most common example of a neutral solution is pure water.
• Neutral solutions have an equal number of hydrogen ions (H⁺) and hydroxide ions (OH^-).

In our examples, none of the substances listed have a pH of 7, so we don't see any neutral solutions.
Understanding neutral pH is important, particularly in biology and chemistry. For instance, our blood is slightly basic with a pH around 7.4, which is crucial for our survival.

chemical analysis

Chemical analysis involves studying substances to understand their composition and properties.
When dealing with pH, chemical analysis can:

• Help determine if a solution is acidic, basic, or neutral.
• Identify the concentration of different ions in a solution.
• Provide valuable insights for applications in medicine, environmental science, and various industries.

For instance: Analyzing the pH of rainwater is essential in environmental science to understand acid rain and its impact.
Similarly, knowing the pH of household items like cola or photo developer can help ensure safe usage.
Accurate chemical analysis relies on exact measurements and proper techniques like titrations, use of pH meters, and indicators.