suppose group of volunteers is planning on building a park near a local lake the
ID: 1040706 • Letter: S
Question
suppose group of volunteers is planning on building a park near a local lake the lake is known to measure low levels of As therefore prior to starting construction the group decides to measure the current level of arsenic in the lake A) if a 14.9 Jump to t Set 532/100 Gradebe Print Calcuator Periodic Table on 9 of 15 Sapling Learning Map Suppose a group of volunteers is on building a park near a local lake. The lake is known to contain low levels of arsenic (As) Therefóre, prior to starting construction, the group decides to measure the current level of arsenic in the lake. a) If a 14.9 cm2 sample of lake water is found to have 176.7 ng As, what is the concentration of arsenic in the sample in parts per billion (ppb), assuming that the density of the lake water is 1.00 g/om? Number ppb One of the volunteers suggests hiring an on-site water treatment y to remove the arsenic from the claims their process takes 2.11 days to remove 39.60 kg of As from a water source b) Calculate the total mass (in kg) of arsenic in the lake that the company will have to remove if the total volume of water in the lake is 0.350 km Number kg on the will it take to remove all of the arsenic from the lake, assuming that there are always 365 days in a year? Number years enat", Q) check Answer 0 Next ?E.Explanation / Answer
a) Since density = 1 gm/mL
So, Mass = Density * Volume = 14.9 cm^3 * 1g/cm^3 = 14.9g
Mass of As = 176.7 ng = 1.76 * 10^(-7)g
(1.76 * 10^(-7))/(14.9) = 1.181 * 10^(-8) = 11.81 ppb
b)
1 Km = 1000 m = 10^5 cm
Volume of lake in cm^3 = 0.5 * 10^(15) cm^3 = 5 * 10^(14) cm^3
Mass of arsenic in lake = 5 * 10^(14)g * 176.7 * 10^(-9)g/14.9g = 59.295 * 10^5 grams = 5929.5 Kg
c)
Number of days = 5929.5/39.60 * 2.11 = 315.94 days
Number of years = 315.94/365 = 0.8655 years
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