NC Wastewater Lab Analyst Grade 1 QUESTIONS
AND CORRECT DETAILED ANSWERS WITH
RATIONALES |AGRADE
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Terms in this set (99)
Acidity refers to the presence and concentration of
What is acidity? hydrogen ions (H⁺) in a solution, which determines
how acidic that solution is.
Acids
What are the sources of Carbon Dioxide
acidity? Oxides of Sulfur or Nitrogen
Organic Acids
, Apparatus and Reagents:
Sample Container: Glass or plastic bottles, ensuring
minimal exposure to air.
Titrant: 0.02 N Sodium Hydroxide (NaOH) solution,
standardized.
Indicators:Phenolphthalein: For measuring acidity to
pH 8.3 (used for strong acids).Methyl Orange or
Bromcresol Green: For measuring total acidity to pH
4.5 (measuring both strong and weak acids).
pH Meter: Calibrated, to monitor pH endpoints.
Distilled Water: For dilutions and cleaning.
Burette: For precise titrant delivery.
2. Sample Collection and Holding Time:
Sample Collection: Collect the water sample in a
clean, airtight container and hold at 4 C.
Holding Time: 14 Days
Procedure:
Describe the test Step 1: Preparation
procedure for acidity Collect a known volume of the water sample (e.g., 100
including reagents, mL) in a beaker.
holding time, and If necessary, filter to remove any suspended solids.
calculation. Step 2: Indicator Addition
Add 2-3 drops of the appropriate indicator to the
sample.
For strong acid measurement (to pH 8.3), use
phenolphthalein.
For total acidity (to pH 4.5), use methyl orange or
bromcresol green.
Step 3: Titration
Fill the burette with standardized 0.02 N NaOH.
Slowly titrate the sample while stirring, adding NaOH
drop by drop.
Monitor the pH using a pH meter or observe the color
change corresponding to the endpoint (pH 4.5 or pH
8.3, depending on the type of acidity being
measured).
The endpoint is reached when the pH remains stable
, at the desired value (or the color change persists for
30 seconds).
Given appropriate Vol NAOH (ml) x Normality of NAOH x 50,000
laboratory data, be able ------------------------------------------------
to calculate acidity. Volume of the sample (ml)
Alkalinity is the capacity of a solution, typically water,
to neutralize acids. It reflects the presence of alkaline
What is alkalinity?
substances (bases) that can accept hydrogen ions
(H⁺) or neutralize acidic components.
Bicarbonate (HCO₃⁻): The most common form of
alkalinity in natural waters, especially in groundwater
and surface waters.
Carbonate (CO₃²⁻): Found in more alkaline waters
What are the sources of
with higher pH values.
alkalinity?
Hydroxide (OH⁻): Present in waters with very high pH.
Other Sources: Some waters may also contain
borates, silicates, phosphates, and ammonia, which
can contribute to alkalinity.
AND CORRECT DETAILED ANSWERS WITH
RATIONALES |AGRADE
Save
Terms in this set (99)
Acidity refers to the presence and concentration of
What is acidity? hydrogen ions (H⁺) in a solution, which determines
how acidic that solution is.
Acids
What are the sources of Carbon Dioxide
acidity? Oxides of Sulfur or Nitrogen
Organic Acids
, Apparatus and Reagents:
Sample Container: Glass or plastic bottles, ensuring
minimal exposure to air.
Titrant: 0.02 N Sodium Hydroxide (NaOH) solution,
standardized.
Indicators:Phenolphthalein: For measuring acidity to
pH 8.3 (used for strong acids).Methyl Orange or
Bromcresol Green: For measuring total acidity to pH
4.5 (measuring both strong and weak acids).
pH Meter: Calibrated, to monitor pH endpoints.
Distilled Water: For dilutions and cleaning.
Burette: For precise titrant delivery.
2. Sample Collection and Holding Time:
Sample Collection: Collect the water sample in a
clean, airtight container and hold at 4 C.
Holding Time: 14 Days
Procedure:
Describe the test Step 1: Preparation
procedure for acidity Collect a known volume of the water sample (e.g., 100
including reagents, mL) in a beaker.
holding time, and If necessary, filter to remove any suspended solids.
calculation. Step 2: Indicator Addition
Add 2-3 drops of the appropriate indicator to the
sample.
For strong acid measurement (to pH 8.3), use
phenolphthalein.
For total acidity (to pH 4.5), use methyl orange or
bromcresol green.
Step 3: Titration
Fill the burette with standardized 0.02 N NaOH.
Slowly titrate the sample while stirring, adding NaOH
drop by drop.
Monitor the pH using a pH meter or observe the color
change corresponding to the endpoint (pH 4.5 or pH
8.3, depending on the type of acidity being
measured).
The endpoint is reached when the pH remains stable
, at the desired value (or the color change persists for
30 seconds).
Given appropriate Vol NAOH (ml) x Normality of NAOH x 50,000
laboratory data, be able ------------------------------------------------
to calculate acidity. Volume of the sample (ml)
Alkalinity is the capacity of a solution, typically water,
to neutralize acids. It reflects the presence of alkaline
What is alkalinity?
substances (bases) that can accept hydrogen ions
(H⁺) or neutralize acidic components.
Bicarbonate (HCO₃⁻): The most common form of
alkalinity in natural waters, especially in groundwater
and surface waters.
Carbonate (CO₃²⁻): Found in more alkaline waters
What are the sources of
with higher pH values.
alkalinity?
Hydroxide (OH⁻): Present in waters with very high pH.
Other Sources: Some waters may also contain
borates, silicates, phosphates, and ammonia, which
can contribute to alkalinity.
