Question

5. Use the following data to answer the questions below Substance Methanol CH OH han Temperature Vapor Pressure CH OW) 25.7 ℃ 25.7 °C 15.2 kPa 384°C116 00 C 24.3 kPa 15kPa4AkPa 5Y2a What happens to the vapor pressure of methanol as the temperature increases? Briely eaain the ets a. for the observed trend? methanol and ethanol at 25.7 C What is the reason for the difference in vapor pressure of b. ed with a 0.175 M NaOH solution. f acetic acid is

Answer 1

a. For the same liquid (methanol), as the temperature increases, the vapor pressure of the liquid (methanol) increases.

For the same liquid (methanol), as the temperature decreases, the vapor pressure of the liquid (methanol) decreases.

Explanation: The boiling temperature of a liquid is the temperature at which the liquid boils and turns to vapor at atmospheric pressure. If the liquid is the same (methanol), its vapor pressure is directly related to the temperature.

b. For two different liquids, as the boiling temperature increases, the vapor pressure decreases.

Explanation: If the liquids are different (methanol and ethanol), the vapor pressure is inversely related to their boiling temperatures. The boiling temperature of methanol is 65 ^oC, whereas that of ethanol is 78 ^oC, which is more than that of the methanol, hence the vapor pressure of ethanol is less than that of methanol.