Boiling points of solutions Materials : Distilled water (400ml) Celsius thermome
ID: 1067638 • Letter: B
Question
Boiling points of solutions
Materials :
Distilled water (400ml)
Celsius thermometer
Table salt (Nacl)
Procedure :
1. Boil 100 ml of water in 250 ml beaker and note down the temperature in degrees.
2. Dissolve 5 g NaCl in 100 ml of distilled water. Bring this solution to a gentle boil and note down the Boling point of the solution.
3. Add 5g more of NaCl to bring the total NaCl in the solution to 10 g. Record the solution's boiling point in the table.
4. Add 5 more grams of NaCl and measure the Boiling point of the solution.
Questions :
1. The effect of doubling the amount of water instead of the amount of NaCl in step 3??
2. What would happen if you continued to add more salt?? Would this pattern will continue or eventually level off ?? . Design an experiment to test your prediction.
Amount of salt/g Boiling point of water/degrees C AV 0 100.5 100 100 100 5 105 104 105 105 109 109 110 109 10 117 119 15 118 118Explanation / Answer
Sodium chloride is a non-volatile solute.So addition of NaCl to water lowers the vapor presssure of solution,then the temperature of the solution must be raised to restore its vapor pressue value to the corresponding value of vapor pressure of pure water. So, the temperature at which the vapor pressure of NaCl solution is 1 atmosphere will be higher; the boiling point of NaCl solution will be raised.In case of dilute solution the elevation of boiling point is directly proportional to molal conentrations of NaCl.
1.The effect of doubling the amount of water instead of the amount of NaCl in step 3 will bring down the boiling point as the molal conentrations of NaCl is brought to half of its original concentration.
2.The trend of elevation in boiling point of NaCl solution will continue to some extent and level off as the solution gets saturated,