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professor190 [17]
4 years ago
7

Polychlorinated biphenyls (PCBs) are major environmental pollutants. Which of the following detectors would be most sensitive fo

r GC analysis of PCBs? (24-8) Group of answer choices flame photometric (FPD) electron capture (ECD) flame ionization (FID) thermal conductivity (TCD) nitrogen-phosphorus (NPD)
Chemistry
2 answers:
Pie4 years ago
8 0

Answer: The detectors that would be most sensitive for GC analysis of PCBs are

- Electron Capture Detectors (ECD)

Explanation:

Polychlorinated biphenyls(PCBs) are oily chemicals that are manufactured(man-made) and used as lubricants in electrical equipments such as transformers. They are grouped as major environmental pollutants because they are characterised as being very stable, as they are resistant to extreme temperature and pressure. Therefore with time the build up in the environment and can cause harmful health effects.

In the environment, it can be found distributed virtually everywhere incl, air water or soil. The PCBs can be analysed in the environment through the use of gas chromatography( GC) with electron capture detector (ECD) as the most sensitive detector. The method was found to be more sensitive as the number of chlorine atoms attached to the biphenyl increases.

aalyn [17]4 years ago
7 0

Answer:

electron capture detectors (ECD)

Explanation:

Electron capture detectors (ECD) would be most sensitive for GC analysis of PCBs.

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PLEASE HELP FAST IM ABOUT TO FAIL PLEASE HELP PLEASE HELP FAST HELP HELP THIS IS DESPRATE
MariettaO [177]

1. 0.240 liters of water would be needed to dissolve 21.6 g of lithium nitrate to make a 1.3 M (molar) solution.

2. 2.9 M is the molarity of a solution made of 215.1 g of HCl is dissolved to make 2.0 L of solution.

3.83.3 ml of concentrated 18 M H2SO4 is needed to prepare 250.0 mL of a 6.0 M solution.

4. 135 ml of stock HBr will be required to dilute the solution.

5. 150 ml of water should be added to 50.0 mL of 12 M hydrochloric acid to make a 4.0 M solution

6. The pH of the resulting solution is 13.89

Explanation:

The formula used in solving the problems is

number of moles= \frac{mass}{atomic mass of one mole}      1st equation

molarity = \frac{number of moles}{volume}            2nd equation

Dilution formula

M1V1 = M2V2          3rd equation

1. Data given

mass of Lithium nitrate = 21.6 grams

atomic mass of on emole lithium nitrate = 68.946 gram/mole

Molarity is given as 1.3 M

VOLUME=?

Calculate the number of moles using equation 1

n = \frac{21.6}{68.946}

  = 0.313 moles of lithium nitrate.

volume is calculated by applying equation 2.

volume = \frac{0.313}{1.3}

            = 0.240 litres of water will be used.

2. Data given:

mass of HCl = 215.1 gram

atomic mass of HCl = 36.46 gram/mole

volume = 2 litres

molarity = ?

using equation 1 number of moles calculated

number of moles = \frac{215.1}{36.46}

number of moles of HCl = 5.899 moles

molarity is calculated by using equation 2

M = \frac{5.899}{2}

   = 2.9 M is the molarity of the solution of 2 litre HCl.

3. data given:

molarity of H2SO4 = 18 M

Solution to be made 250 ml of 6 M

USING EQUATION 3

18 x V1= 250 x 6

V1 = 83.3 ml of concentrated 18 M H2SO4 will be required.

4. data given:

M1= 10M, V1 =?, M2= 3 ,V2= 450 ml

applying the equation 3

10 x VI = 3x 450

V1 = 135 ml of stock HBr will be required.

5. Data given:

V1 = 50 ml

  M1= 12 M

  V2=?

  M2= 4

applying the equation 3

50 x 12 = 4 x v2

V2 = 150 ml.

6. data given:

HCl + NaOH ⇒ NaCl + H20

molarity of NaOH = 0.525 M

volume of NaOH = 25 ml

molarity of acid HCl= 75 ml

volume of HCl = 0.335 ml

pH=?

Number of moles of NaOH and HCl is calculated by using equation 1 and converting volume in litres

moles of NaOH = 0.0131

moles of HCl= 0.025 moles

The ratio of moles is 1:1 . To find the unreacted moles of acid and base which does not participated in neutralization so the difference of number of moles of acid minus number of moles of base is taken.

difference of moles = 0.0119  moles ( NaOH moles is more)

Molarity can be calculated by using equation 1 in (25 +75 ml) litre of solution

molarity = \frac{0.0119}{0.1}

             = 0.11 M (pOH Concentration)

14 = pH + pOH  

  pH  = 14 - 0.11

     pH    = 13.89

3 0
3 years ago
What causes each new row of the periodic table
taurus [48]

Answer:

elements have the same number of valence electrons and similar chemical properties.

Explanation:

they have the same number

8 0
3 years ago
Vitamin is an organic compound whose deficiency in the human body can cause apathy, irritability, and an increased susceptibilit
Mnenie [13.5K]

Answer:

a) 21 bonds , and 4 bonds

b) bond angles , a < 109.5° , b ≈ 120° c < 109.5° d,e < 120° f ≈ 120° g ≈ 109.5°

c) 6 carbon atom are sp² hybridized

d) two carbon atoms are sp³ hybridized,

    two oxygen atoms are sp³ hybridized

    Nitrogen is not sp³ hybridized , it has sp² hybridization

e) vitamin B6 exhibit delocalized bonding, because the three double bond in ring are delocalized over 5 carbon atoms and one nitrogen atom , they are formed due to  6 p orbitals of 5 carbons and 1 Nitrogen atom. The bonding in vitamin B6  is similar to the Benzene.

Explanation:

7 0
4 years ago
Which biome has leaves that change colors and fall off as winter approaches?
steposvetlana [31]

Answer:

Fall

Explanation:

Fall is before winter

3 0
4 years ago
Read 2 more answers
What are F- centers?
mars1129 [50]

Explanation:

An F-center, Farbe center or color center is a type of crystallographic defect in which an anionic vacancy in a crystal lattice is occupied by one or more unpaired electrons. Electrons in such a vacancy tend to absorb light in the visible spectrum such that a material that is usually transparent becomes colored.

6 0
3 years ago
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