Gravimetric Analysis

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Experiment 1 - Gravimetric Analysis

Application Question: Exposure to contaminated water

In this example, we apply the values from the previous calculations to determine the effects and toxicity of samples of water on the human population.

For this example, let's assume an average body mass of 100 kg, that there are 100 mL of blood per kg of body mass, that 5% of ingested lead is absorbed in the blood stream and that a person drinks 2 L of water per day. (Refer to Table 1 in the Experiment 1 section of the lab manual for additional toxicity information).

Recall from the lab manual, that your sample of lead was boiled down from 1000 L of water. Using the data from your previous calculations, estimate how long will it take for the townsfolk to experience kidney failure if exposed to this contaminated water.

Hint

days

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The following tutors are a step by step walkthrough that show the details on how to solve the above problem.

Based on Table 1 in the lab manual, at what blood lead level is kidney failure a symptom of lead toxicity?

Hint

mg/L

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Table 1 shows that kidney failure is an effect of lead poisoning when the level of lead in the blood is 0.800 mg/L.

What is the mimimum amount of lead that must be present in the blood stream of a 100 kg person in order for them to experience kidney failure?

Hint

grams Pb

Assuming that only 5% of the ingested lead is absorbed into the bloodstream, what is the required minimum dose for kidney failure?

grams Pb

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The minimum amount of lead present in blood stream to experience kidney failure is: (100kg) x (0.1 L blood per kg) x (0.800 mg/L) = 8.00 mg = 0.00800 g

Hint:

The dose required for kidney failure is (0.800 mg/L / 0.05%) = 0.16 g

How much lead is ingested when the original sample, concentrated from a 1000 L of water is ingested?

Hint

grams Pb

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Since the 0.8758 g sample is concentrated from a 1000 L and is shown to contain 41.52% lead, the amount of Pb ingested per 1000 L is?

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(0.8758 g sample) x (0.4152) = 0.3636 g Pb has been ingested per 1000 L drank.

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What volume of water does the person need to drink in order to experience kidney failure?

Hint

L water

In how many days has the person drank this volume of water?

days

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Using the above data, the result is: (0.16g) x (1000 L) / (0.3636 g Pb) = 440 L

Hint:

The result is: 440L / 2L per day = 220 days.

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