Practice Mass Balance For Pollutant In The Lake (1.7) - Air-Water Exchange

Practice: Mass Balance for Pollutant in the Lake

Lesson 1.7Air-Water Exchange

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9 questions

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2 cards from this section. Quick, good the night before a test.
Exercise
6 questions · about 4 min · pass mark 70%. Hints available.
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3 questions · about 2 min · pass mark 70%. Hints available.
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6 sample questions

Question 1.
Define what is meant by mass balance.
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Think about how we measure inputs and outputs in a system.
Question 2.
What are the two main components of mass balance?
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Consider the flow of materials.
3Question 3.
What is the formula for mass balance?
- Rate of Output = Rate of Input
- Rate of Accumulation = Rate of Input - Rate of Output
- Rate of Accumulation = Rate of Input + Rate of Output
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Think about what accumulates over time.
4Question 4.
True or False: Evaporation can directly contribute to the input of pollutants into a lake.
- True
- False
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Consider where pollutants go.
Question 5.
A lake with a depth of 2 meters and a surface area of 5000 m^2 has an initial concentration of pollutant A of 1 kg/m^3. If a factory discharges 200 kg/day into the lake and evaporation removes 50 kg/day, calculate the concentration after three days.
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Consider the overall mass accounting across the time in your calculations.
Question 6.
If a pollutant is continuously added to a well-mixed lake, and after three days the concentration is observed to be 1.5 kg/m^3 with continuous inputs of 75 kg/day and evaporation of 25 kg/day, calculate the initial concentration prior to any discharge.
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You will need to set up the mass balance equation to find initial values.

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