Acidity and pH of Rainwater

The video tutorial demonstrates how to test the pH of rainwater using pH paper. The instructor, Dr. B, collects rainwater and compares its pH to known solutions: hydrochloric acid (pH 0), a neutral solution (pH 6.86), and sodium hydroxide (pH 14). The rainwater turns the pH paper slightly green, indicating a pH between 5 and 6, which is acidic. This acidity is attributed to carbon dioxide in the air forming carbonic acid. The video also discusses how industrial pollution can further acidify rainwater, aligning with EPA data.

What is the purpose of collecting rainwater in the experiment?

• To check its purity

• To measure its temperature

• To determine its pH level

• To analyze its color

What color does pH paper turn when testing a strong acid like hydrochloric acid?

• Green

• Blue

• Red

• Yellow

Which pH value is considered neutral?

• 0

• 7

• 14

• 5

What is the pH level of a strong base like sodium hydroxide?

• 5

• 14

• 7

• 0

What was the observed pH range of the collected rainwater?

• Between 0 and 1

• Between 5 and 6

• Between 7 and 8

• Between 13 and 14

Why is rainwater naturally acidic?

• Because of carbon dioxide absorption

• Due to its mineral content

• Because of its high temperature

• Due to the presence of sulfur dioxide

What weak acid is formed when rainwater absorbs carbon dioxide?

• Nitric acid

• Carbonic acid

• Hydrochloric acid

• Sulfuric acid

How can industrial sites affect the acidity of rainwater?

• By reducing its pH

• By increasing its temperature

• By making it more alkaline

• By releasing sulfur dioxide

What does the pH of rainwater indicate about its nature?

• It is basic

• It is acidic

• It is neutral

• It is alkaline

Which organization provides known values for the pH of rainwater in the U.S.?

• CDC

• EPA

• FDA

• NASA