CWS Water Chemistry & Contaminant Identification 2

Question 1

Which parameter is used to measure the ability of water to neutralize acids?

Accepted Answer

Alkalinity

Answer

Alkalinity measures water's capacity to neutralize acids, primarily due to bicarbonate, carbonate, and hydroxide ions.

Question 2

What is the maximum contaminant level (MCL) for nitrates in drinking water set by the EPA?

Accepted Answer

10 mg/L

Answer

The EPA MCL for nitrates in drinking water is 10 mg/L (as nitrogen) to prevent methemoglobinemia in infants.

Question 3

Trihalomethanes (THMs) in drinking water are primarily formed when:

Accepted Answer

Chlorine reacts with natural organic matter

Answer

THMs form as disinfection byproducts when chlorine reacts with naturally occurring organic matter in source water.

Question 4

A water sample has a pH of 5.5. This water would be classified as:

Accepted Answer

Slightly acidic

Answer

A pH of 5.5 is below the neutral point of 7.0, making the water slightly acidic.

Question 5

Which dissolved gas is the primary cause of red water complaints related to iron?

Accepted Answer

Oxygen

Answer

Dissolved oxygen causes ferrous (clear) iron to oxidize into ferric (red/brown) iron, producing red water complaints.

(CWS) Certified Water Specialist Practice Test