1. A tank containing 1 million gallons of a liquid at a temperature of 100 degrees Fahrenheit is filled with an n additional 1,000,000 gallons of the same liquid at a temperature of 50 degrees Fahrenheit.

a. How do you think this will affect the temperature of the final solution if mixed?
b. How do you think making variations in the second volume would affect the final temperature?
c. How do you think making variations in the second volume temperature would affect the final temperature?

2. A gallon of water has a concentration of 1000 part per million (PPM) of a radioactive particle.500 ppm is the maximum amount of water that can be transported the volume does not matter.

a. If you have available water with 0ppm concentration how many equal volume dilutions must you perform in order to bring the concentration below the limit for transport?
b. If the water you were using to dilute the original has a concentration of 250 ppm how would this affect your process? What happens if the concentration is 400ppm?
c. If you let the original solution evaporate the particles stay in the remaining solution would the affect your efforts to dilute later?

3. The concentrations of carbon dioxide (CO2) found in most schools and offices are usually well below the 5,000 ppm occupational safety standard-the time-weighted average for a 10-hour workday within a 40-hour workweek-for an industrial workplace. While levels below 5,000 ppm are considered to pose no serious health impacts, experience indicates that individuals in schools and offices with elevated CO2 concentrations tend to report drowsiness, lethargy, and a general sense of stale air. Researchers are looking for linkages between elevated CO2 concentrations

and reduced productivity and achievement. A building has a CO2 concentration of 2,000 ppm with a total volume of 1,000,000 cubic feet.

Questions:
a. With complete and vigorous mixing of air volumes, how much volume must you change in the building to reduce the concentration of CO2 by half if the outside air concentration is 0 ppm?
b. Since outside air normally contains 350 ppm CO2, how would this affect the volume needed to change-out to reduce the initial concentration of CO2 by half?
c. The ventilation systems recirculate much of the air and bring only a portion of outside air into the building. How does this impact the dilution of CO2?

4. All the preceding scenarios assume that no more of the pollutant is introduced while you are performing your dilution and mixing.
Questions:
a. If the pollutant was constantly introduced, how would this affect the dilution efforts? Draw a simple graph over time of concentrations of the pollutant and how it is affected by the serial dilutions while the pollutant addition rate is constant.
b. If during the dilutions, the air removal via exhaust fans to reduce CO2 concentration is not linear, the flow changes due to pressure changes inside the building and the introduction of fresh air is not linear. How will this affect the dilution problem?
c. If the rate at which the pollutant is added also changes, how will this affect the dilution process?