1. Consider the following compounds: ethanol, CH 3 CH 2 OH; dimethyl ether, CH 3

Question

1. Consider the following compounds:

ethanol, CH3CH2OH; dimethyl ether, CH3OCH3; and propane, CH3CH2CH3. The boiling points are -42.10C, -230C, and 78.50C.

Match the boiling points to the correct compounds and explain.

2. Calcium has a cubic close packed structure as a solid. Assuming that calcium has atomic radius of 197 pm, calculate the density of the solid calcium.

3. X-rays of wavelength 2.63Å were used to analyze a crystal. The first order diffraction (n = 1 in Bragg equation) was 55.55o. Calculate the spacing between crystal planes and what would be the angle for second order diffraction.

4. The normal boiling point for acetone is 56.5oC. At an elevation of 5300 ft the atmospheric pressure is 630 torr. What would be the boiling point of acetone at this elevation (Hvap = 32.0 kJ/mol). What would be the vapor pressure of acetone at 25.0oC at this elevation?

Explanation / Answer

1) order of boiling points :

ethanol, CH3CH2OH ---------------> 78.50C

dimethyl ether, CH3OCH3 --------------> -230C

propane, CH3CH2CH3 ----------------->    -42.10C

explanation:

1) ethanol contain -OH group it can form hydrogen bond itself . the intermolecular forces are stronger in ethanol so it has highest boiling point

2) both ether and alkane having dispersion forces. but due to high molar mass ethers having greater boilining point than alkane .

least boiling point always for alkane compared to remaining due to weak dispersion forces

Related Questions

Navigate

• Browse (All)
• Browse 1
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.