Materials
Electric hot plate
2 identical 1L beakers
Digital thermometer (±0.1°C accuracy)
Table salt (NaCl)
Measuring spoons
Distilled water
Timer
Procedure
1. Measure 500ml of distilled water into each beaker.
2. Add 30g of table salt to beaker B. Leave beaker A as pure water control.
3. Place both beakers on identical hot plates set to maximum.
4. Monitor temperature continuously with digital thermometer.
5. Record the temperature at which a full rolling boil is observed.
6. Repeat 3 times for each condition.
Observations
Pure water boiled at an average of 100.1°C across 3 trials (100.0, 100.1, 100.2). Salt water boiled at an average of 101.8°C across 3 trials (101.7, 101.9, 101.8). Salt water took approximately 45 seconds longer to reach boiling. Both beakers showed pre-boiling bubble formation at around 95°C.
Notes
The 1.7°C elevation matches the theoretical prediction from boiling point elevation calculations for this concentration. The colligative property is well-established. Good introductory chemistry investigation.