Question

Suppose a group of volunteers is planning to build a park near a local lake. The lake is known to contain low levels of arsenic (As). Therefore, prior to starting construction, the group decides to measure the current level of arsenic in the lake.

If a 13.9 cm3 sample of lake water is found to have 165.1 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/cm3?

concentration:__________________________ ppb

One of the volunteers suggests hiring an on‑site water treatment company to remove the arsenic from the lake. The company claims their process takes 2.00 days to remove 44.40 kg of arsenic from a water source. Calculate the total mass, in kilograms, of arsenic in the lake that the company will have to remove if the total volume of water in the lake is 0.490 km3.

total mass: _______________________kg

Based on the company's claim and the concentration of arsenic in the lake, how many years will it take to remove all of the arsenic from the lake, assuming that there are always 365 days in a year?

number of years: ________________________years

Answer 1

Comment in case of any doubt.

→ 13.9 cat mass = 13.9 cm x + g = 13.9 g cm3 = 13.99 Concentration of (in ppb) Arsenic = 1 mass of Arsenic(ing) x109 mass of solution ling) = 165.1 xlo?g x10 - [11.9 ppb 13.9g Total mass of arsenic in the lake = 0.490 km (100 m (10 crore 1-2 gas) 10g mass arm solltion) a concentration of As en lake of lake ing 5.82 x 106 g = 55. kg) I - loong → Time taken to remove 5.82x10 5820 kg) Arsenic = Total arsenic to be removed - Rate of arsenic removal 5820 kg kg = 262.2 days /+ year 144.40kg I 2 days ) converting 365days days to year = [0.718 year]