solution_part4 (1).pdf. Solution chapter 1 class 12
- 5. Elevation in boiling point Boilingpoint of a liquidis the temperature at which the vapour pressureof the liquid becomes equal to the atmosphericpressure The boilingpoint of a solutioncontaininga non-volatilesoluteis always higher than boilingpoint of the pure solvent.This increasein boilingpoint is known as elevationin boilingpoint. The vapourpressureof the solutionis lower than that of pure solvent and vapour pressurincreaseswith increasein temperature . Hence the solutionhas to be heated more to make the vapourpressureequal to the atmosphericpressure.
- 6. Elevation in boiling point ATMOSPHERIC PRESSURE
- 7. Molalityelevation constant may be defined as the elevation in boilingpoint when the molalityof the solutionis unity. Molalityis the number of moles of the solute dissolved per 1000g of the solvent. Elevationin boilingpoint is directly proportionalto lowering of vapour pressure. ∆p α ∆Tb Acc to Raoult’slaw ∆p α x2 ∆Tb α x2 ∆Tb = k M1 n2 / w1 ELEVATION IN BOILING POINT
- 9. Questions: 1. Define molal elevation constant, 2. What is meant by colligative properties? 3. Explain boiling point elevation constant for a solvent. 4. Out of 1M glucose and 2M glucose , which one has higher boiling point and why? 5. Why does a solution containing non volatile solute have higher boiling point than pure solvent ? 6. Why is elevation of boiling point is a colligative properties.
- 10. Depression in freezing point • Freezing point of a substance is the temperature at which the solid and liquid forms of the substance are in equilibrium. • The vapour pressure of the solution is less than that of the pure solvent . • freezing point of the solution is always lower than that of pure solvent.
- 11. DEPRESSION IN FREEZING POINT
- 12. DEPRESSION IN FREEZING POINT Molalitydepression constant may be defined as the elevationin boiling point when the molalityof the solution is unity. Molalityis the number of moles of the solute dissolved per 1000g of the solvent. ∆p α ∆Tf ∆p α x2 ∆Tf α x2 ∆Tf = k M1 n2 / w1
- 14. Question 1. What is molal depression constant? 2. Will the depression in freezing point be same or different , if 0.1 mole of sugar or 0.1 mole of glucose is dissolved in 1L of water? 3. It is advised to add ethylene glycol to water in car radiatorwhile driving in hill station,Why? 4. How does sprinkling of salt help in clearing the snow covered roads in hilly areas?