13 • IMF's, Liquids, and Solids

• AP Chemistry

Name ________________________________ Period ___ Date ___/___/___

13 • IMF’s, Liquids, and Solids BOILING PRACTICE Vapor Pressures of Various Liquids

Temperature (°C) –10 –5 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

Ethyl Alcohol (mmHg) 5.6 8.3 12.2 17.3 23.6 32.2 43.9 59.0 78.8 103.7 135.3 174.0 222.2 280.6 352.7 448.8 542.5 666.1 812.6 986.7 1187 1420 1693.3

Benzene (mmHg) 19 25 33 43 56 71 91 114 143 176 216 263 317 379 451 531 622 720 843 968 1122 1270 1463

Methyl Salicylate (mmHg)

1.41 1.90 2.52 3.40 4.41 5.90 7.63 9.93 12.8

Water (mmHg) 2.1 3.2 4.6 6.5 9.2 12.8 17.5 23.8 31.8 42.2 55.3 71.9 92.5 118.0 149.4 190.0 233.7 289.1 355.1 433.6 525.8 633.9 760.0

Carbon Tetrachloride (mmHg) 15 20 27 35 45 58 74 94 118 147 182 225 271 325 389 462 547 643 753 877 1020 1180 1360

Ex1. A beaker of benzene (C6H6) is at room temperature (20° C). What is its vapor pressure? ______mmHg Is this vapor pressure large enough to cause the benzene to boil at sea level? _____ Ex2. All of the liquids are heated to 80°C, circle those that will be boiling when the air pressure is 760 mmHg. ethyl alcohol benzene methyl salicylate water carbon tetrachloride Ex3. If the temperature remains unchanged, but the pressure above the liquids is reduced to 700 mmHg, circle those substances that will be boiling. ethyl alcohol benzene methyl salicylate water carbon tetrachloride

Problems: 1.

A beaker of ethyl alcohol at room temperature (20° C) and a beaker of benzene at room temperature are both placed on a hot plate on a day when the air pressure is only 700 mmHg. Which one of the two liquids will start to boil first? ________________ … It will boil at about what temperature? _________

2.

A beaker of carbon tetrachloride is warmed to 60° C and connected to a vacuum pump so the air pressure above the liquid can be changed. The pump is turned on. At what pressure will the liquid start to boil? ______mmHg What would this pressure be in atmospheres? ______ atm [show calculation here]

3.

At 75° C, in a place where the air pressure is only 650 mmHg, circle the substances that will be boiling. ethyl alcohol benzene methyl salicylate water carbon tetrachloride

4.

The pressure above the five substances is adjusted to 550 mmHg. What is the approximate boiling point of each substance at this pressure? [methyl salicylate is excluded] ethyl alcohol benzene water carbon tetrachloride _____ _____ _____ _____

5.

At 550 mmHg, when the temperature is hot enough to get the ethyl alcohol to boil, will the carbon tetrachloride also be boiling? ____

6.

At 75° C, I start the pressure above the liquids at 760 mmHg and slowly reduce it using the vacuum pump. In which order will the substances boil? 1st__________ 2nd__________ 3rd__________ 4th__________ 5th__________

7.

Determine the approximate “normal boiling point” of each substance below: ethyl alcohol benzene water carbon tetrachloride _____ _____ _____ _____

8.

Study the chart of vapor pressures at 25° C. Rate the five substances in terms of their IMF’s (intermolecular forces of attraction). strongest IMF’s ____________________ ____________________ ____________________ ____________________ weakest IMF’s ____________________

9.

Why doesn’t data for methyl salicylate start until 60° C? _____________________________________ _____________________________________________________________________________