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elixir [45]
3 years ago
15

Calculate the number-average molecular weight of a random nitrile rubber [poly(acrylonitrile-butadiene) copolymer] in which the

fraction of butadiene repeat units is 0.27; assume that this concentration corresponds to a degree of polymerization of 2000.
Chemistry
1 answer:
SCORPION-xisa [38]3 years ago
7 0

Answer:

106,504 g/mol

Explanation:

The two repeat units at the polymer are the acrylonitrile and the butadiene. If the fraction of repeat of butadiene is 0.27, the fraction of repeat of units of acrylonitrile must be 0.73.

The acrylonitrile repeat unit has 3 carbons atoms, 1 nitrogen atom, and 3 hydrogen atoms. So, the molecular weigth for it is:

mac = 3*mC + 1*mN + 3*mH

mC = 12 g/mol; mN = 14 g/mol; mH = 1g/mol

mac = 3*12 + 14 + 3*1 = 53 g/mol

The butadiene repeat unit has 4 carbons atoms and 6 hydrogen atoms. Thus, the molecular weight is:

mbu = 4*12 + 6*1 = 54 g/mol

The average repeat unit molecular weight is the fractions multiplied by the molecular weight of the repeat unities:

m = 0.73*53 + 0.27*54 = 53.27 g/mol

The number-average molecular weight is the average repeat unit molecular weight  multiplied by the degree of polymerization:

M = 53.27*2000

M = 106,504 g/mol

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(On the verge of tears)
zhenek [66]

Answer: The final molarity of a 20mL- 1.3M salt solution after it has been diluted with 100ml water is 0.22 M

Explanation:

According to the dilution law,

M_1V_1=M_2V_2

where,  

M_1 = molarity of stock solution = 1.3  M

V_1 = volume of stock solution = 20 ml  

M_1 = molarity of diluted solution = ?

V_1 = volume of  diluted solution = (20+100) ml = 120 ml

Putting in the values we get:

1.3\times 20=M_2\times 120

M_2=0.22M

Therefore  the final molarity of a 20mL- 1.3M salt solution after it has been diluted with 100ml water is 0.22 M

7 0
3 years ago
All of the following are examples of matter except
Alexxandr [17]

A. Heat because it does not take up space.

3 0
3 years ago
The following forces act on an object: 3N left, 2N up, 1N right, 2N down.
Ymorist [56]
The answer is 2N left.
8 0
4 years ago
Determine the empirical formula for a compound that is 70.79% carbon, 8.91% hydrogen, 4.59% nitrogen, and 15.72% oxygen.
Debora [2.8K]

Answer:

The answer to your question is:       C₁₈ H₂₇ N O₃

Explanation:

Data

Carbon = 70.79 g

Hydrogen = 8.91 g

Nitrogen = 4.58 g

Oxygen = 15.72 g

Process

AT C = 12 g

AT H = 1 g

AT N = 14 g

AT O = 16 g

                   Carbon

                                  12 g ------------------------  1 mol

                           70.79  g -------------------------   x

                                 x = (70.79 x 1) / 12

                                 x = 5.9 mol of C

                  Hydrogen

                                   1 g -----------------------  1 mol

                                8.91 g ---------------------   x

                                  x = (8.91 x 1) / 1

                                  x = 8.91 mol of H

                  Nitrogen

                                 14 g ---------------------- 1 mol

                                4.58 g -------------------   x

                                   x = (4.58 x 1) / 14

                                   x = 0.33 mol

                  Oxygen

                               16 g ------------------------  1 mol

                               15.72 g --------------------   x

                                  x = (15.72 x 1)/16

                                 x = 0.98

Divide by the lowest number of moles

Carbon               5.9 / 0.33     =  17.9   ≈ 18

Hydrogen           8.91 /  0.33  =   27

Nitrogen             0.33 / 0.33  =    1

Oxygen               0.98 / 0.33 =    2.9  ≈ 3

                             C₁₈ H₂₇ N O₃

4 0
4 years ago
Which answer correctly describes the difference between covalent and ionic bonds?
elena-14-01-66 [18.8K]

Answer:

Ionic: Transfer of electrons

Covalent: sharing of electrons

Explanation:

Ionic bonding is between a metal and a non metal. The metals loses electrons while the non metal gains electrons

Covalent bonding is where two non non metals share electrons.

4 0
3 years ago
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