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In a science lab, 5.00 g of NaOH(s) is dissolved in 300 mL of water. What is the molar concentration ofÂ
the resulting solution?
A hydrocarbon was found to contain 0.96g of carbon and 0.2g of hydrogen. Calculate the simplest formula
If 5 g of acetic acid 5 g of sodium acetate are dissolved to produce a liter of solution, what is the hydronium ion concentration of the solution? What is the pH of the solution?
1. A lake with constant volume 10 x 106 m3
is fed by a pollution-free stream with flow rate 50 m3
/s. A factory
dumps 5 m3
/s of a conservative waste with concentration 100 mg/L into the lake. The pollution has the reaction
rate coefficient K of 0.25/day. Assume the pollution is well mixed in the lake. Find the concentration of pollution
in the lake.
2. A lagoon is to be designed to accommodate an input flow of 0.10 m3
/s of non-conservative pollutant with
concentration 30 mg/L and reaction rate 0.20/day. The effluent from the lagoon must have pollutant
concentration of 5 mg/L. Assuming complete mixing, how large must the lagoon be?
1. Incoming wastewater, with BOD5 equal to about 200 mg/L is treated in a well-run secondary treatment plant
that removes 90% of the BOD. You are to run a 5-day BOD test with a standard 300 mL bottle, using a mixture
of treated sewage and the dilution water (no seed). Assuming that the initial DO is 9.2 mg/L,
a. Roughly, what maximum volume of treated wastewater should you put in the bottle is you want to have at
least 2 mg/L at the end of the test (filling the rest of the bottle with water)?
b. If you make a mixture of half water and half treated wastewater, what DO would you expect after 5 days?
2. A mixture consisting of 30 mL of waste and 270 mL of seeded dilution water has an initial DO of 8.55 mg/L;
after 5 days, it has a final DO of 2.40 mg/L. Another bottle containing just the seeded dilution water has an initial
DO of 8.75 mg/L and a final DO of 8.53 mg/L. Find the 5-day BOD of the waste.
A researcher tries to find out the mass percent composition of an Iron ore sample. The
researcher weighted 1.30 g of Iron ore and dissolved it in HI (aq) solution. Based on the
given redox reaction generated Fe2+ is titrated with 32.5 mL of 0.088 M of potassium
permanganate. Find the mass percent Fe in the ore sample? What if the researcher dilutes
the potassium permanganate solution to half and uses the same volume of solution for
titration, how many grams of iron remains unreacted?
Fe2+ + Mn04 > Fe3+ + Mn2+
A company uses Ha gas to generate electricity. They studied a smaller scale model reaction
to figure out the maximum amount of H2 gas that they can produce. For this purpose, they
used an alloy consisting of 95% Al by mass. The alloy has a density of 3.12 g/cm" and they
took a 0.875 cm? small piece of alloy to react with 200 mL of 1.2 M solution of HCI based on
the given Al specific reaction. What is the maximum amount of H2 gas that can be produced?
What are the limiting and remaining reagents? How can they increase the amount of Ha gas
that they obtained?
AI + HCI > AICIz + H2 (not balanced)
A company uses Ha gas to generate electricity. They studied a smaller scale model reaction to figure out the maximum amount of H2 gas that they can produce. For this purpose, they used an alloy consisting of 95% Al by mass. The alloy has a density of 3.12 g/cm and they took a 0.875 cm small piece of alloy to react with 200 mL of 1.2 M solution of HCI based on the given Al specific reaction. What is the maximum amount of Ha: gas that can be produced? What are the limiting and remaining reagents ? How can they increase the amount of Ha gas that they obtained? AlHCI AICls H2 (not balanced)
What mass of barium was in the original solution? (Assume that all of the barium was precipitated out of solution by the reaction.)
SITUATIONAL ANALYSIS:
Two fishers went spearfishing, one using gas cylinder and the other without using any breathing apparatus. At depths of 100ft, fishers are subject to approximately 5atm. As they go deeper, the fisher without breathing apparatus is experiencing difficulty breathing while the other feels normal. Assuming a typical gas cylinder contains 50 grams of O2 and 250 grams of He and has a volume of 8.0 L. What is the partial pressure of each gas at 25 OC? What is the total pressure inside the cylinder? Why does the fisher without breathing apparatus experience difficulty breathing as he went deeper?
