1. The vapor pressure of dichloromethane, CH2Cl2, at 0C is 134mmHg. The normal boiling point of dichloromethane is 40C. Calculate its molar heat of vaporization
The answer is in kilojoules per mole.
I know i use the Clausius-Clapeyron equation but i don't know what to plug in.
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2. Classify each property as associated with a liquid that has strong or weak intermolecular forces.
A. LOW BOILING POINT- weak
B. HIGH BOILING POINT- strong
C. LOW VAPOR PRESSURE
D. HIGH VAPOR PRESSURE
E. HIGH SURFACE TENSION
F. LOW SURFACE TENSION
G. HIGH Viscosity
H. LOW Viscosity
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3. The Society of Automotive Engineers has established an accepted numerical scale to measure the viscosity of motor oil. For example, SAE 40 motor oil has a higher viscosity than an SAE 10 oil.
Rank the following hydrocarbons by their expected viscosity.
Rank from most to least viscous.
a. CH3CH2CH2CH2CH2CH3
b. CH3CH2CH2CH2CH2CH2CH2CH3
c. CH3CH2CH2CH2CH2CH2CH2CH2CH2CH3
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#1.
Well, 0 degrees C the v.p. is 134. I would call those T1 and P1 (Be sure to convert T1 to Kelvin).
The problem lists the normal boiling point as 40 degrees C. Convert that to Kelvin. The vapor pressure at the normal boiling point is 760 mm Hg. So those are T2 and P2. R is 8.314 J/mol. Delta H will have the units J/mol.
2. Classify each property as associated with a liquid that has strong or weak intermolecular forces.
A. LOW BOILING POINT- weak
B. HIGH BOILING POINT- strong
C. LOW VAPOR PRESSURE
D. HIGH VAPOR PRESSURE
E. HIGH SURFACE TENSION
F. LOW SURFACE TENSION
G. HIGH Viscosity
H. LOW Viscosity
A and B are ok. Think about them while answering the others. A liquid that has low vapor pressure has a high boiling point, does it not. And a liquid that has high vapor pressure has a low boiling point.
Surface tension is how the surface molecules stick together. High surface tension means they stick together very well, low surface tension means they don't. Viscosity is how "thick" the material is. If it pours easily, it has low viscosity; if it pours with difficulty (like molasses) it has high viscosity. High viscosity means the molecules don't slide past each other easily so they must have high intermolecular forces.
3. The Society of Automotive Engineers has established an accepted numerical scale to measure the viscosity of motor oil. For example, SAE 40 motor oil has a higher viscosity than an SAE 10 oil.
Rank the following hydrocarbons by their expected viscosity.
Rank from most to least viscous.
a. CH3CH2CH2CH2CH2CH3
b. CH3CH2CH2CH2CH2CH2CH2CH3
c. CH3CH2CH2CH2CH2CH2CH2CH2CH2CH3
I would think that the higher the molecular weight and the longer the chain, the easier it would be to get tangled up with each other Wouldn't that sound reasonable to you? Then 3 would have the highest viscosity and 1 would have the lowest. Check my thinking.
Thank You got all the answers
Rank from greatest to least surface tension.
1. To calculate the molar heat of vaporization using the Clausius-Clapeyron equation, you will need the vapor pressure at two different temperatures (in this case 0°C and the boiling point, 40°C). The equation is given by:
ln(P2/P1) = -(ΔHvap/R) * (1/T2 - 1/T1),
where P1 and P2 are the vapor pressures at temperatures T1 and T2, ΔHvap is the molar heat of vaporization, and R is the ideal gas constant.
In this case, you are given the vapor pressure at 0°C (P1 = 134 mmHg) and you can assume the vapor pressure at the boiling point (P2) is atmospheric pressure, which is 760 mmHg. The temperatures should be converted to Kelvin (T1 = 273K and T2 = 313K).
Now, you can substitute the known values into the equation:
ln(760/134) = -(ΔHvap/R) * (1/313 - 1/273).
Solving for ΔHvap, you can rearrange the equation to:
ΔHvap = -(RT) * ln(P2/P1),
where R is the ideal gas constant (8.314 J/(mol·K)). Since the answer is required in kilojoules per mole, you can convert the value of R to kJ/(mol·K) by dividing by 1000.
Finally, substitute the values and calculate the molar heat of vaporization.
2. To classify the properties associated with strong or weak intermolecular forces:
A. LOW BOILING POINT - weak intermolecular forces
B. HIGH BOILING POINT - strong intermolecular forces
C. LOW VAPOR PRESSURE - strong intermolecular forces
D. HIGH VAPOR PRESSURE - weak intermolecular forces
E. HIGH SURFACE TENSION - strong intermolecular forces
F. LOW SURFACE TENSION - weak intermolecular forces
G. HIGH VISCOSITY - strong intermolecular forces
H. LOW VISCOSITY - weak intermolecular forces
Strong intermolecular forces lead to higher boiling points, lower vapor pressures, higher surface tensions, and higher viscosities. Weak intermolecular forces result in lower boiling points, higher vapor pressures, lower surface tensions, and lower viscosities.
3. To rank the hydrocarbons by their expected viscosity:
Viscosity generally increases with longer and more complex molecular structures. Therefore, the hydrocarbon with the longest chain (c) will have the highest viscosity, followed by the hydrocarbon with the second-longest chain (b), and finally the hydrocarbon with the shortest chain (a):
c. CH3CH2CH2CH2CH2CH2CH2CH2CH2CH3
b. CH3CH2CH2CH2CH2CH2CH2CH3
a. CH3CH2CH2CH2CH2CH2CH2CH2CH2CH3