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AlladinOne [14]
2 years ago
15

The insecticide DDT has a half-life in the human body of approximately 7 years. [In 7 years its concentration decreases to half

its initial concentration). Although DDT is no longer used in the United States, 25 years ago that average farmer had a body DDT concentration of 22ppm [parts per million by weight). Estimate what the farm workers present concentration is?
Chemistry
1 answer:
iragen [17]2 years ago
3 0

Answer:

explanation below

Explanation:

Dichlorodiphenyltrichloroethane, also known as DDT is a chemical compound that is found in insecticides. In 1972, the United States Environmental Protection Agency issued an order for the cancellation of requests for the chemical compound because it affects wildlife and pose risks to humans as well.  

From the question here, it was noted that the initial concentration was 22ppm 25years ago and so if it takes 7years to decay by half, the actual concentration in present day farmers could be calculated as follows;

25years ago  - 22ppm

18years ago  - 11ppm

11years ago – 5.5 ppm

4 years ago -  2.75ppm

Since 7yrs = 0.5

Then 4yrs will be [ [4/7] x 0.5] = 0.2857

Then if 0.5 = 2,

Then 0.2857 = [ [ 0.2857/0.5] x 2] = 1.1428

So present year concentration would then be [2.75ppm/1.1428] = 2.406ppm

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6. Un volumen de 1.0 mL de agua de mar contiene casi 4 x 10-12 g de Au. El volumen total de agua en los océanos es de 1.5 x 1021
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V=1.5\times10^{24}\ mL

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1\ ml\ volume = 4\times10^{-2}\ g

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1 year ago
BH+ClO4- is a salt formed from the base B (Kb = 1.00e-4) and perchloric acid. It dissociates into BH+, a weak acid, and ClO4-, w
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Answer:

The pH of 0.1 M BH⁺ClO₄⁻ solution is <u>5.44</u>

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Given: The base dissociation constant: K_{b} = 1 × 10⁻⁴, Concentration of salt: BH⁺ClO₄⁻ = 0.1 M

Also, water dissociation constant: K_{w} = 1 × 10⁻¹⁴

<em><u>The acid dissociation constant </u></em>(K_{a})<em><u> for the weak acid (BH⁺) can be calculated by the equation:</u></em>

K_{a}. K_{b} = K_{w}    

\Rightarrow K_{a} = \frac{K_{w}}{K_{b}}

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<em><u>Now, the acid dissociation reaction for the weak acid (BH⁺) and the initial concentration and concentration at equilibrium is given as:</u></em>

Reaction involved: BH⁺  +  H₂O  ⇌  B  +  H₃O+

Initial:                     0.1 M                    x         x            

Change:                   -x                      +x       +x

Equilibrium:           0.1 - x                    x         x

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As, x

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2 years ago
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