text: An increase in pressure causes the boiling point to go up. Think about it like this, at higher pressures, the molecules will be pushed closer together, to the point where intermolecular attractions become significant and the vapor condenses to form a liquid. It takes more energy (i.e. higher temperature) to allow the molecules to break free into the gas phase.\n\nThis is also why the boiling point of water is less at high elevations; there's less pressure, so it's easier to make water boil.\n\nAnother thing to note: The boiling point is defined as the point where the vapor pressure of the substance equals the surrounding pressure. Since vapor pressures generally increase with increasing temperature, an increase in surrounding pressure raises the temperature needed to maintain that equality.