Flint MI received a lot of attention over the past two years. In some of the stu
ID: 484738 • Letter: F
Question
Flint MI received a lot of attention over the past two years. In some of the studies of their water the Pb concentrations were as much as 0.900 ppm. Untreated lead exposure can result in permanent brain damage and other neurological problems. You may assume that the lead solution has the same density as water. What is this concentration of the solution in w/v%? What is the mole fraction of lead in the solution? Tire repair shops always get incredibly busy in January in Fort Wayne because the low tire volume alarm goes off in cars and everyone assumes they have a leak in their tires. You may assume the pressure remains the same. Explain what is happening and why this is happening at the molecular level? Based off of your answer for part a, what gas law relationship applies to this scenario?Explanation / Answer
2
(a)
1 ppm = 0.001 mg/mL
So, 0.9 ppm = 0.0009 mg/mL
Mass of Pb in 100 mL sample = 0.0009*100 = 0.09 mg = 0.00009 g
So , w/v% of Pb in sample = 0.00009 %
(b)
Density of sample = 1 g/mL = 1000 mg/mL
Mass of 1 mL sample = 1000 mg
Mass of Pb in 1 mL of sample = 0.001 mg
So, mass of water = 1000-0.001 mg = 999.999 mg
Moles of water = 999.999/18000 = 0.056 moles
Moles of Pb = 0.001/207000 = 4.83*10-9 moles
Since moles of Pb are neligible, so mole fraction is practically zero.
(3)
(a)
This is because in January because of lower temperatures, the average kinetic energy of molecules decreases, and they tend to be more compact than usual because of the lesser energy content. This causes the tire volume to get less and less as the temperatures keep dropping.
(b)
Since pressure is assumed constant, assuming air as an ideal gas, Charle's law comes into action, which states that at constant pressure, gas volume is directly proportional to temperature.
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.