30 Questions
What is the purpose of alkalinity measurement in water chemistry?
To measure the buffering capacity of water
Which of the following is NOT a major inorganic constituent commonly found in terrestrial water?
Iron
How is alkalinity typically expressed in water analysis reports?
In equivalent per liter (eq/L)
Which of the following is a key component contributing to the overall alkalinity in most water systems?
Carbon dioxide
What does a decrease in pH from 8.5 to 4.5 indicate in terms of water chemistry?
Increase in acidity
Which parameter is used to quantify the acid required to lower the pH of a water sample to 4.5?
[H+]
What is the main cause of water hardness?
Presence of multivalent cations
Which ions contribute to the total hardness in practice?
Ca2+ and Mg2+
What is the most common unit used to express water hardness in terms of equivalent CaCO3 mass?
mg/L as CaCO3
How is Equivalent Weight (EW) calculated?
Atomic weight divided by valence charge
Which compound has an Equivalent Weight of 50 g/eq?
CaCO3
What ions are involved in the dissolution of CaCO3?
Ca2+ and Cl-
What is the size range of viruses?
0.01 – 0.1 µm
Which organism is a parasitic worm?
Giardia lamblia
What is the infectious dose that N50 represents?
10,000,000
Which microorganism is particularly resistant to chemical disinfectants?
Cryptosporidium parvum
In a Plaque Assay, what does a plaque refer to?
A void of host cells formed by infection with a single virus particle
Where did the Milwaukee pathogen outbreak of 1993 occur?
Milwaukee, Wisconsin
What is the purpose of recarbonation in the water softening process?
To prevent scaling caused by excess calcium carbonate
What does the parameter 𝐺𝑡𝑑 represent?
A combination of velocity gradient and detention time
In the Lime-Soda process, what is added in order to remove magnesium non-carbonate hardness?
Soda ash (Na2CO3)
Why do bigger plants typically have lower energy consumption in coagulation-flocculation processes?
Due to higher technological efficiency and trained staff
What is the outcome of the reaction between Ca(OH)2 and CO2 during recarbonation?
Formation of calcium carbonate scale
What is the primary cause of water hardness?
Multivalent cations like Calcium and Magnesium
Excess water hardness can lead to poor lathering performance of soaps due to:
Formation of hard precipitates on infrastructure
How does the Lime-Soda process contribute to water softening?
By adding carbonate to precipitate hardness ions
What is the primary function of the ion exchange process in water softening?
Exchanging sodium ions for calcium and magnesium ions
What is the formula to calculate Total Hardness (TH) in mg/L as CaCO3?
$50,000(2[Ca2+] + 2[Mg2+])$
What are the most abundant dissolved inorganic constituents found in water that contribute to water hardness?
Calcium and Magnesium
Why is soda ash (Na2CO3) added in the Lime-Soda process for water softening?
To precipitate calcium and magnesium ions
Test your knowledge on the major inorganic constituents in terrestrial water, including calcium, magnesium, sodium, potassium, bicarbonate, chloride, sulfate, silica, sulfur, and nitrate. Explore cumulative curves and frequency distribution of various constituents to understand their concentrations.
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