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# CHEMISTRY QUESTION PLEASE HELP?

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, before starting construction, the group decides to measure the current level of arsenic in the lake.

A. If a 13.3 cm3 sample of lake water is found to have 160.5 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?

B. 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 2.61 days to remove 42.60 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 0.650 km3.

C. 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?

### 1 Answer

- Bobby_ThinLv 74 months agoFavorite Answer
A) (160.5*10^-9 g) / ((13.3 cm^3)*(1.00 g/cm^3)) = 12.067*10 ^-9

.. = 12.07 ppb

B) (0.650 km^3)*((10^4 dm)/km)^3*(1 kg/dm^3)*(12.07*10^-9)= 7850 kg

C) = (7,850 kg)*(2.61 days)/(42.6 kg) = 480 days or

= 1.32 years

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