Why are atoms more stable when combined?

2. Calculate the number-average molecular weight of a random poly (isobutylene-isoprene) copolymer in which the fraction of isob

Phoenix [80]

Answer : The number-average molecular weight is, 97500 g/mol

Explanation :

First we have to calculate the molecular weight of isobutylene and isoprene.

The molecular formula of isobutylene and isoprene is, $C_4H_8$ and $C_5H_8$

Molecular weight of $C_4H_8$ = 4(12 g//mol) + 8(1 g/mol) = 56 g/mol

Molecular weight of $C_5H_8$ = 5(12 g//mol) + 8(1 g/mol) = 68 g/mol

Now we have to calculate the average repeat molecular weight.

Average repeat molecular weight = $0.25\times (56g/mol)+(1-0.25)\times (68g/mol)$

Average repeat molecular weight = 65 g/mol

Now we have to calculate the number-average molecular weight.

Number-average molecular weight = Average repeat molecular weight × Degree of polymerization

Number-average molecular weight = (65 g/mol) × (1500)

Number-average molecular weight = 97500 g/mol

Thus, the number-average molecular weight is, 97500 g/mol

5 0

3 years ago

A 150.0 mL sample of an aqueous solution at 25°C contains 15.2 mg of an unknown nonelectrolyte compound. If the solution has an

inysia [295]

Answer: The molar mass of the unknown compound is 223.2 g/mol

Explanation:

To calculate the concentration of solute, we use the equation for osmotic pressure, which is:

$\pi=iMRT$

where,

$\pi$ = osmotic pressure of the solution = 8.44 torr

i = Van't hoff factor = 1 (for non-electrolytes)

M = molarity of solute = ?

R = Gas constant = $62.3637\text{ L torr }mol^{-1}K^{-1}$

T = temperature of the solution = $25^oC=[273+25]=298K$

Putting values in above equation, we get:

$8.44torr=1\times M\times 62.3637\text{ L. torr }mol^{-1}K^{-1}\times 298K\\\\M=\frac{8.44}{1\times 62.3637\times 298}=4.54\times 10^{-4}M$

To calculate the molecular mass of solute, we use the equation used to calculate the molarity of solution:

$\text{Molarity of the solution}=\frac{\text{Mass of solute}\times 1000}{\text{Molar mass of solute}\times \text{Volume of solution (in mL)}}$

We are given:

Molarity of solution = $4.54\times 10^{-4}M$

Given mass of unknown compound = 15.2 mg = 0.0152 g (Conversion factor: 1 g = 1000 mg)

Volume of solution = 150.0 mL

Putting values in above equation, we get:

$4.54\times 10^{-4}M=\frac{0.0152\times 1000}{\text{Molar mass of unknown compound}\times 150.0}\\\\\text{Molar mass of unknown compound}=\frac{0.0152\times 1000}{150.0\times 4.54\times 10^{-4}}=223.2g/mol$

Hence, the molar mass of the unknown compound is 223.2 g/mol

5 0

3 years ago

Balance the equation C2H4O2 + O2 → CO2 + H2O

blsea [12.9K]

Answer:

Explanation:

$C_{2}H_{4}O_{2}+2O_{2}$ → $2CO_{2}+2H_{2}O$

4 0

3 years ago

How many significant figures are in 0.00102?

zaharov [31]

Answer:

3

Explanation:

102 are significant figures

7 0

2 years ago

Read 2 more answers

If an atom loses 2 electrons, what is the charge on the resulting ion what is an example

saveliy_v [14]

Explanation:

The charge of an ion would be +2

4 0

3 years ago