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MA_775_DIABLO [31]
3 years ago
12

A worker is exposed to the following airborne concentrations of ethylbenzene: 8:00 – 10:00 125 ppm 10:15 – 12:15 88 ppm 12:45 –

3:15 112 ppm 3:30 – 5:00 70 ppm What is the 8-hour TWA exposure for the employee (calculate the exposure)? Does it exceed the OSHA PEL?
Chemistry
1 answer:
postnew [5]3 years ago
8 0

Answer:

The 8-hour TWA exposure for the employee is 101 ppm and it exceeds the OSHA PEL of 100 ppm for ethylbenzene.

Explanation:

The TWA for 8 hours is calculated by the sum of airbone concentrations multiplied by the time it has been exposed to that period. The total is divided by 8 which refers to the 8 hours total the employee has been exposed.

TWA = (125x2+88x2+112x2.5+70x1.5)/8.

The OSHA PEL is a known number for every compound and it can be find in PEL tables. In the case of ethylbenezene, it is 100 ppm.

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A 20.0 mL of 0.27 M solution of the salt NaA has a pH of 8.70.
zlopas [31]

Answer:

a) 3.969

b) 3.489

Explanation:

a) Calculate the pk, value of the acid HA

PH of salt hydrolysis

P^{H} = 1/2 ( pkw + pka + logC )

8.7 * 2 =  14 + log ( 0.27 )  + Pka

∴ Pka = 3.9686  ≈  3.969

b) Calculate the PH of a solution containing 0.3 M HA and 0.1 M NaA

PH = Pka + log ( salt / acid )

    = 3.9686 + log ( 0.1 / 0.3 )

    =  3.9686 - 0.48  = 3.489

3 0
3 years ago
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Answer:

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8 0
3 years ago
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An aqueous solution of iron(II) iodide has a concentration of 0.215 molal. The percent by mass of iron(II) iodide in the solutio
Basile [38]

Answer:

6.24%

Explanation:

Molality by definition means a measurement of the number of moles of solute in solution with 1000 gm or 1Kg solvent. Notice the difference that Molarity is defined on the volume of solution and Molality on the mass of solvent.

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means 0.215 moles are present in 1 Kg of solvent.

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mass of FeI2 = moles x molar mass

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=66.57 gm

mass % of FeI2 = mass of FeI2 x 100 / total mass

= 66.57x 100 / (1000 +66.57)

= 6.24%

                           

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A. H++ SO42- + Ca2+ + 21 → CaSO4 + H+ +1-

B. 2H+ + S042- + Ca2+ + 21° → Ca2+ + SO42- + 2H+ + 21

C. S042- + Ca2+ → CaSO4,

D. 2H+ + SO42- + Ca2+ + 2I- → CaSO4 + 2H+ + 2I-

cancel  the spectator  ion that is the  ions  which  does  not take  place in  the  reaction

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