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Whitepunk [10]
2 years ago
14

Help please science (7th grade)

Chemistry
2 answers:
hoa [83]2 years ago
8 0

Answer:

17

Explanation:

Don't mind the random letters

bshsujsjjdjd

tiny-mole [99]2 years ago
8 0

Answer:

18

Explanation:

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4 0
3 years ago
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The following table lists molecular weight data for a polypropylene material. Molecular Weight Range (g/mol) xi wi
nikklg [1K]

Answer:

a) the number-average molecular weight is 32,400 g/mol

b) the weight-average molecular weight is 36,320 g/mol

c) the degree of polymerization is 770

Explanation:

Given the data in the question;

Molecular                  Mean        Number      Weight      Number        Weight

weight                                                                             average         average

(g/mol)                    Mi(g/mol)         xi                wi          xiMi                  wiMi

8,000-16,000            12,000        0.07           0.03         840                360

16,000-24,000          20,000       0.15           0.09         3000              1800

24,000-32,000         28,000       0.26           0.21          7280              5880

32,000-40,000         36,000       0.27           0.27         9720               9720

40,000-48,000         44,000       0.18            0.28         7920              12320

48,000-56,000         52,000       0.07           0.12          3640              6240

∑                                                                                Mn=32,400     Mw=36,320

so;

a)  the number-average molecular weight

Mn = ∑Mixi

so from the table above; summation of Row Mixi

Mn = ∑Mixi = 32,400

Therefore, the number-average molecular weight is 32,400 g/mol

b) the weight-average molecular weight

Mw = ∑Miwi

so from the table above; summation of Row Miwi

Mw = ∑Miwi = 36,320

Therefore, the weight-average molecular weight is 36,320 g/mol

c) the degree of polymerization

the degree of polymerization of polypropylene can be determined using number-average molecular and repeat unit molecular weight.

now, for polypropylene { CH₂ = CH - CH₃ }

the repeat unit consist of 3 carbon atoms and 6 hydrogen atoms

given that;

Atomic weight of Carbon mC = 12.01 g/mol and

Atomic weight of  Hydrogen mH = 1.008 g/mol

now we find the repeat unit molecular weight of polypropylene

m = nCmC + nHmH

where n is the number of repeat of atoms

so we substitute

m = ( 3 × 12.01) + ( 6 × 1.008)

m = 36.03 + 6.048

m = 42.078 g/mol

now we calculate the degree of polymerization;

DP = Mn / m

so we substitute

DP = 32,400 / 42.078

DP = 769.9985 ≈ 770

Therefore,  the degree of polymerization is 770

3 0
3 years ago
What is the magnetic quantum number value for an element with n = 1?
Citrus2011 [14]

Answer:

0, l is n-1 always, ml is l to -l

6 0
3 years ago
A student submits the following work on the mass number, but he has made a few mistakes. Select the sentences that are incorrect
rewona [7]

Answer

 

Calculating the mass number for an atom requires that we know the atomic number and the number of protons in the atom’s nucleus. The mass number then gives us the average weight of atoms of a given element. However, as long as the number of protons equals the number of neutrons, the values balance out and we always obtain a whole number for the mass number.

Explanation:

those 3

7 0
3 years ago
Consider the generic reaction: 2 A(g) + B(g) → 2 C(g). If a flask initially contains 1.0 atm of A and 1.0 atm of B, what is the
irina1246 [14]

Answer:

b. 1.5 atm.

Explanation:

Hello!

In this case, since the undergoing chemical reaction suggests that two moles of A react with one moles of B to produce two moles of C, for the final pressure we can write:

P=P_A+P_B+P_C

Now, if we introduce the stoichiometry, and the change in the pressure x we can write:

P=1.0-2x+1.0-x+2x

Nevertheless, since the reaction goes to completion, all A is consumed and there is a leftover of B, and that consumed A is:

x=\frac{1.0atm}{2}=0.5atm

Thus, the final pressure is:

P=1.0-2(0.5)+1.0-(0.5)+2(0.5)\\\\P=1.5atm

Therefore the answer is b. 1.5 atm.

Best regards!

3 0
3 years ago
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