Boiling point of water is ______. A. 210° F B. 212° F C. 214° F D. 208° F
B
Understanding the Boiling Point of Water
The boiling point of a substance is the temperature at which it changes from a liquid to a gas (vapor) at a given pressure. For water, this point is well-defined under standard atmospheric pressure.
Water's boiling point is commonly known in different temperature scales:
- In the Celsius scale, the boiling point of water at standard atmospheric pressure is 100° C.
- In the Kelvin scale, this temperature is approximately 373.15 K.
- In the Fahrenheit scale, which is used in the question options, the boiling point of water at standard atmospheric pressure is 212° F.
The question asks for the boiling point of water in degrees Fahrenheit. Based on standard scientific values, the boiling point is 212° F.
Evaluating the Options for Water's Boiling Point
Let's compare the known boiling point of water in Fahrenheit (212° F) with the given options:
- A. 210° F
- B. 212° F
- C. 214° F
- D. 208° F
Option B matches the standard boiling point of water in the Fahrenheit scale.
Conversion Between Temperature Scales
It is useful to know how to convert between Celsius and Fahrenheit. The formula to convert Celsius (°C) to Fahrenheit (°F) is:
$$ \text{°F} = (\text{°C} \times \frac{9}{5}) + 32 $$
Using this formula for the boiling point of water (100°C):
$$ \text{°F} = (100 \times \frac{9}{5}) + 32 $$
$$ \text{°F} = (20 \times 9) + 32 $$
$$ \text{°F} = 180 + 32 $$
$$ \text{°F} = 212 $$
This confirms that 100°C is equivalent to 212°F.
Revision Table: Standard Boiling Points
| Substance | Boiling Point (°C) | Boiling Point (°F) | Boiling Point (K) |
|---|---|---|---|
| Water | 100 | 212 | 373.15 |
| Ethanol | 78.37 | 173.07 | 351.52 |
| Liquid Nitrogen | -195.79 | -320.42 | 77.36 |
Additional Information: Factors Affecting Boiling Point
The boiling point of water is not always exactly 212° F (or 100° C). The boiling point is dependent on the surrounding atmospheric pressure.
- Pressure: At higher altitudes, the atmospheric pressure is lower. This lower pressure means that water boils at a lower temperature. For example, in Denver, Colorado, which is at a high altitude, water boils at about 203° F (95° C). Conversely, under higher pressure (like in a pressure cooker), water boils at a higher temperature.
- Impurities: Dissolving substances (like salt) in water can also affect its boiling point, usually increasing it slightly. This phenomenon is called boiling point elevation.
However, questions asking for the standard boiling point of water generally refer to the value at standard atmospheric pressure, which is 212° F or 100° C.
Therefore, the correct boiling point of water listed among the options is 212° F.
Important Questions from Boiling and Condensation
______ occurs when the vapour pressure is more than pressure above a liquid surface at a given temperature.
When the state is being changed from gas to liquid through the process of condensation, the temperature?
Dropwise condensation usually occurs on
When salt is added to water, then which of the following changes occur -
- A wire is submerged horizontally in water at 5 bar with a saturation temperature of $150^\circ C$. The wire length is 250 mm and diameter is 2 mm. The wire carries a current of 100 A with an applied voltage of 2.5 V. If the surface of the wire is maintained at $200^\circ C$, what is the boiling heat transfer coefficient ?
