Presentation on theme: "The boiling point of a substance is the temperature at which the vapor pressure of the liquid equals the pressure surrounding the liquid and the liquid."— Presentation transcript:
The boiling point of a substance is the temperature at which the vapor pressure of the liquid equals the pressure surrounding the liquid and the liquid changes into a vapour. When water boils, the molecules of the water get heated up and gain energy. It The normal boiling point of water is 100 o C because this is the temperature at which the vapor pressure of water is 760 mm Hg, or 1 atm. Under normal conditions, when the pressure of the atmosphere is approximately 760 mm Hg, water boils at 100 o C. At 10,000 feet above sea level, the pressure of the atmosphere is only 526 mmHg. At these elevations, water boils when its vapour pressure is 526 mmHg, which occurs at a temperature of 90 o C.
Personal Hygiene Temperatures commonly used for personal hygiene are 98°-102° and the comfort range is very narrow. Someone comfortable at 102° would be very uncomfortable at 104°. Federal Law limits Jacuzzi and Spa heaters to 104°. Dishes Dishwashers normally have their own internal heating elements. It is not the temperature of the water but the combination of the hot water and the soap that kills germs. Remember that to kill germs with hot water you would have to use water heated to 212° (boiling water), which no home appliance is permitted to do for safety reasons. Clothes Clothing is normally washed in cold or warm water. Hot water causes clothing to shrink and fade.