Describe an experiment to determine the saturation vapour pressure of water in the temperature range 25°c-70°c. sketch the curve you would except to obtain
To determine the saturation vapor pressure of water in the temperature range of 25°C to 70°C, you can conduct an experiment using an apparatus called a "saturated water vapor pressure apparatus" or a "dew point apparatus." This apparatus allows you to measure the pressure of the water vapor at different temperatures.
Here's the step-by-step procedure for the experiment:
1. Set up the apparatus: Start by assembling the saturated water vapor pressure apparatus. It usually consists of a sealed chamber filled with water, a thermometer to measure the temperature, and a pressure gauge or manometer to measure the pressure of the vapor.
2. Calibrate the apparatus: Before starting the experiment, calibrate the pressure gauge or manometer using a known reference pressure at a specific temperature. This will ensure accurate measurements.
3. Prepare the temperature range: Fill the sealed chamber with distilled water and heat it using a controlled heating source such as a water bath or electric heater. Make sure the temperature can be controlled within the desired range of 25°C to 70°C.
4. Measure the pressure: Once the water reaches the desired temperature, monitor the temperature using the thermometer and record the corresponding pressure reading from the pressure gauge or manometer. Repeat this step for each temperature within the range.
5. Plot the data: After collecting all the pressure and temperature measurements, plot the data on a graph with temperature (x-axis) and pressure (y-axis). The resulting curve is known as the "vapor pressure curve" or "water vapor pressure curve."
The sketch of the curve you would expect to obtain is as follows:
- At lower temperatures, such as 25°C, the vapor pressure will be relatively low. As the temperature increases, the vapor pressure will also increase.
- As the temperature reaches 100°C, the boiling point of water at standard atmospheric pressure, the vapor pressure will equal the atmospheric pressure of 1 atmosphere (101.325 kPa or 760 mmHg).
- The curve will show an exponential increase as the temperature rises, indicating that the saturation vapor pressure of water increases significantly with temperature.
Please note that the data points from the experiment need to be precise and consistent to obtain an accurate curve.