Question

State whether each of the following solutions is acidic, basic, or neutral: a. blood, \(\mathrm{pH} 7.38\) b. vinegar, \(\mathrm{pH} 2.8\) c. drain cleaner, \(\mathrm{pH} 11.2\) d. coffee, \(\mathrm{pH} 5.54\) e. tomatoes, \(\mathrm{pH} 4.2\) f. chocolate cake, \(\mathrm{pH} 7.6\)

Short answer

a. basic, b. acidic, c. basic, d. acidic, e. acidic, f. basic

Step-by-step solution

Understanding pH Scale

The pH scale ranges from 0 to 14. A pH of 7 is neutral. Values less than 7 are acidic, and values greater than 7 are basic.

Determine the pH for Blood

Given: Blood, \(\mathrm{pH} 7.38\). The pH is slightly above 7, indicating that blood is basic.

Determine the pH for Vinegar

Given: Vinegar, \(\mathrm{pH} 2.8\). The pH is much less than 7, indicating that vinegar is acidic.

Determine the pH for Drain Cleaner

Given: Drain Cleaner, \(\mathrm{pH} 11.2\). The pH is much greater than 7, indicating that drain cleaner is basic.

Determine the pH for Coffee

Given: Coffee, \(\mathrm{pH} 5.54\). The pH is less than 7, indicating that coffee is acidic.

Determine the pH for Tomatoes

Given: Tomatoes, \(\mathrm{pH} 4.2\). The pH is less than 7, indicating that tomatoes are acidic.

Determine the pH for Chocolate Cake

Given: Chocolate cake, \(\mathrm{pH} 7.6\). The pH is slightly above 7, indicating that chocolate cake is basic.

Key concepts

Acidic Solutions

Acidic solutions have a pH less than 7. The lower the pH number, the stronger the acid. For example, vinegar has a pH of 2.8, indicating it's quite acidic. Coffee and tomatoes are also acidic, with pH values of 5.54 and 4.2, respectively.
Acids can be found in many everyday items:

• Citrus fruits like lemons and oranges
• Pickles and fermented foods
• Soft drinks and wines

They typically taste sour and can turn blue litmus paper red. Acids are also reactive and can dissolve certain metals.

Basic Solutions

Basic solutions, or alkaline solutions, have a pH greater than 7. The higher the pH number, the stronger the base. For example, drain cleaner has a pH of 11.2, making it a strong base. Blood and chocolate cake are also basic, though only slightly, with pH values of 7.38 and 7.6, respectively.
Common basic substances include:

• Baking soda
• Soap and detergents
• Ammonia

Bases often feel slippery to the touch, taste bitter, and can turn red litmus paper blue. They are commonly used in cleaning products due to their ability to neutralize acids.

Neutral Solutions

Neutral solutions have a pH of exactly 7. Pure water is the most common example of a neutral solution.
Characteristics of neutral solutions include:

• They are neither acidic nor basic.
• They do not change the color of litmus paper.
• They have a balanced concentration of hydrogen ions (H+) and hydroxide ions (OH-).

Neutral solutions are essential in various biological and chemical processes, ensuring that reactions occur without favoring acidity or alkalinity.