Question

1. If the amount of mercury in a polluted lake is 0.400ug Hg/ml, what is the total mass in KILOgrams of mercury in the lake? The lake has a surface area of 105 square miles and has an average depth of 23.0 ft. PLEASE SHOW WORK THANKS

2. A 40 pound bag of peat moss needs to be spread onto a flower bed that measures 48 inches by 36 inches. Calculate the depth of the peat moss in meters. The density of peat moss is 0.132 grams/cm3 .

Show your work neatly and methodically. Be sure you work supports your answer.

Answer 1

We have the density which is 0.400 ug/mL and the area, and the depth. The only thing that I have doubt is because I don't know what shape could I use for the lake and then calculate the volume, so, If you could please say which form may I use I could solve this better. I'll assume is a paralellpipede:

Converting depth to cm: 23 ft * 30.48 cm/ft = 701.04 cm

Now the same with the area: 105 mi² * (160900 cm/mi)² = 2.72x10¹² cm²

The volume now: V = 2.72x10¹² * 701.04 = 1.91x10¹⁵ cm³

Now the mass: m = d*V = 0.400 ug/mL * 1.91x10¹⁵ mL = 7.62x10¹⁴ ug

Converting to kg: 7.62x10¹⁴ ug * 1kg/1x10⁹ ug = 762,000 kg

Question 2 is solved in a similar way, just pass the mass from pound to gram, then calculate the volume with the density, and assuming a paralell solve for depth. If you like to be solved, then post this question in another question thread. Hope this helps