A mixture contains several different organic liquids all of which boil at temperatures greater than 50°C. The compounds present in the mixture are separated. Three of the compounds, compounds X, Y and Z, are analysed as follows. Compound X is vaporised. At a temperature of 120°C and a pressure of 115 kPa, a 0.376 g sample of the vapour occupies 124 mL. a. Calculate the molar mass, in g mol⁻¹, of compound X. Compound Y is an alkanol of molecular formula C₄H₁₀O. b. i. In the boxes below, draw the structural formulas, showing all bonds, of the four possible alkanols with a molecular formula of C₄H₁₀O.

SSCE VCE Chemistry Structure, Nomenclature, and Properties of Organic Compounds: A mixture contains several diffe

A mixture contains several different organic liquids all of which boil at temperatures greater than 50°C - VCE - SSCE Chemistry - Question 4 - 2008 - Paper 1

Question 4

A mixture contains several different organic liquids all of which boil at temperatures greater than 50°C. The compounds present in the mixture are separated. Three o... show full transcript

Worked Solution & Example Answer:A mixture contains several different organic liquids all of which boil at temperatures greater than 50°C - VCE - SSCE Chemistry - Question 4 - 2008 - Paper 1

Step 1

Calculate the molar mass, in g mol⁻¹, of compound X.

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Answer

To calculate the molar mass of compound X, we will use the ideal gas equation:

$PV = nRT$

Where:

P = pressure in kPa = 115 kPa
V = volume in L = 0.124 L (since 124 mL = 0.124 L)
n = number of moles
R = ideal gas constant = 8.314 J/(mol·K)
T = temperature in Kelvin = 120 + 273.15 = 393.15 K

First, we need to rearrange the equation to find the number of moles (n):

$n = \frac{PV}{RT}$

Substituting the values:

$n = \frac{(115 \times 0.124)}{(8.314 \times 393.15)}$

Calculating this gives:

$n = \frac{8.83}{3269.09} \approx 0.0027 \text{ moles}$

Next, we find the molar mass (M) using the formula:

$M = \frac{m}{n}$

Where:

m = mass of the sample = 0.376 g

Substituting the values:

$M = \frac{0.376}{0.0027} \approx 139.26 \text{ g mol⁻¹}$

Thus, the molar mass of compound X is approximately 139.26 g mol⁻¹.

Step 2

In the boxes below, draw the structural formulas, showing all bonds, of the four possible alkanols with a molecular formula of C₄H₁₀O.

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Answer

Alkanol I: 1-butanol
- Structure:
  
  H H H H | | | | H-C-C-C-O-H | | | | H H H H
Alkanol II: 2-butanol
- Structure:
  
  H H H H | | | | H-C-C-C-O-H | | | | H H OH H
Alkanol III: 1-methylpropan-1-ol (isobutanol)
- Structure:
```
H  H  H
|  |  |  
```
H-C-C-C-O-H | | | H H H
Alkanol IV: 2-methylpropan-1-ol (tert-butanol)
- Structure:
```
H  H  H
|  |  |  
```
H-C-C-C-O-H | | |
H H H

A mixture contains several different organic liquids all of which boil at temperatures greater than 50°C - VCE - SSCE Chemistry - Question 4 - 2008 - Paper 1

Worked Solution & Example Answer:A mixture contains several different organic liquids all of which boil at temperatures greater than 50°C - VCE - SSCE Chemistry - Question 4 - 2008 - Paper 1

Calculate the molar mass, in g mol⁻¹, of compound X.

In the boxes below, draw the structural formulas, showing all bonds, of the four possible alkanols with a molecular formula of C₄H₁₀O.

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