Boiling Point of Water: Why Does It Vary?
Most people know that water boils at 212°F (100°C), but the truth is that it doesn’t always. Depending on where you are, the boiling point of water can actually vary, sometimes by quite a bit. In this article, we’ll take a look at what affects the boiling point of water, why it matters, and why the boiling point varies at different locations.
Altitude Affects Boiling Point
The most common reason people experience a difference in the boiling point of water is because of altitude. As you move away from sea level and upwards, atmospheric pressure decreases. This decrease in pressure affects the boiling point of water: the higher the altitude, the lower the boiling point.
At sea level, atmospheric pressure is 101.325 kPa, and water boils at 212°F (100°C). For every 1,000 feet that you go up in the air, the atmospheric pressure drops by 1.0, and the boiling point of water will drop by about 1°F for every 500 feet. So, for example, in Denver, Colorado (altitude 5,280 feet), water boils at about 203°F.
Other Factors Affect Boiling Point
In addition to altitude, there are a few other factors that can affect the boiling point of water. The most notable of these is barometric pressure—essentially, how tough air molecules are pushed together. This is determined by a number of things, including air temperature, humidity, clouds, and air pressure.
The salinity of the water can also have an effect on the boiling point. Saltier water has higher boiling points than freshwater, simply because of the added dissolved minerals in the water. The boiling point of water can be increased or decreased by 0.5°F for every 1,000 mg/L of salt depletion or concentration.
Why Does It Matter?
Understanding the boiling point of water is important for a number of reasons. For example, it helps us to understand what’s happening when we’re cooking, as some recipes call for water to boil, but at different temperatures. In baking and other types of cooking, boiling water at a lower temperature can create more delicate dishes.
It’s also helpful to know the boiling point of water when you’re cleaning or performing other tasks around the house. When it comes to water purification, boiling water at a lower temperature won’t be as effective. Water needs to reach a certain temperature in order to kill bacteria and other germs, so understanding the boiling point of water can help you make sure you’re effectively purifying your water.
Conclusion
The boiling point of water varies depending on where you are. Elevation and barometric pressure have the biggest influences, but the salinity and other factors can also affect the boiling point. As you’re cooking, cleaning, or purifying water, knowing the boiling point of water at your location can help you ensure that you’re doing it safely and effectively.