Determination of boiling point
- 1. Determination of molecular weight By Elevation Boiling Point Prepared By: Sara S. Sdiq Zaynab Q. Salih Raman R. Rasheed Zaytun E. Ali Salahaddin University-Erbil College Of science Chemistry Department 2nd Stage 2022-2023 Supervised By: Dr.Ropak A.Sheakhmohamad MS.Aveen .M Hanna
- 2. 1. Definition Of Boiling point 2. Colligative Properties of solution 3. Factors affecting Boiling point 4. Procedure 5. Calculation & definition of the symbols Content
- 3. Definition Ø Boiling point is the temperature at which the vapor pressure of the liquid is equal to the atmospheric pressure and change its state from a liquid to a gas. Ø In terms of intermolecular interactions the b.p. represents the energy required to overcome the various intermolecular attractions binding the molecules as a liquid (e.g. dipole-dipole attraction and hydrogen bonding). Therefore the boiling point of a liquid is also an indicator of the strength of the attractive forces between the liquid's molecules.
- 4. Colligative Properties Of Solution ● Colligative properties are properties of solutions that depend solely on the number of particles dissolved in the solution. -The colligative properties do not depend on the types of solute particles. ● Colligative properties are the physical property Of Solution .
- 5. Colligative Properties Of Solution • There are four common types of Colligative properties. 1. Vapor pressure lowering 2. Freezing point depression 3. Boiling point elevation 4. Osmotic pressure
- 6. Factors affecting boiling point (b.p) 1. Pressure 2. Molecular weight 3. Impurities 4. Structure of the molecule & intermolecular interactions Like A. Branching B. Polarity C. Van der waal interactions D. H-bonding
- 7. Factors affecting boiling point (b.p) 1. Pressure a.When the pressure is less than 1 atm, the boiling point of the liquid is less than its normal b.p. b.When P = 1 atm, the b.p. of the liquid is called normal boiling point c.When P is greater than 1 atm, the b.p. of the liquid is greater than its normal b.p.
- 8. Factors affecting boiling point (b.p) 2. Molecular weight By increasing molecular weight boiling point increase
- 9. Factors affecting boiling point • The boiling point of pure H2O is 100 celsius, but that boiling point can be elevated by adding a solute such as a salt. 3. Impurities • A solution has higher boiling point pure solvent.
- 10. Factors affecting boiling point 4. Structure of the molecule & intermolecular interactions A. Branching Within the branched series, increased branch leads to lower boiling point.
- 11. Factors affecting boiling point 4. Structure of the molecule & intermolecular interactions. B. Polarity Polarity rises boiling point.
- 12. Factors affecting boiling point 4. Structure of the molecule & intermolecular interactions 3. Van der waal interactions As the number of carbon in an alkanes increase, the boiling point increase due to the large surface area and van der waal interactions increased
- 13. Factors affecting boiling point 4. Structure of the molecule & intermolecular interactions 4. Hydrogen bonding Hydrogen bonding increases the boiling point of a compound . This is because hydrogen bonds are strong intermolecular attractive forces that create stable molecules.
- 14. Procedure
- 15. Calculation m=molal concentration of the solution we know that molality is the number of moles of solute per kilogram of the solvent Now we know that molality is the number of moles of solute per kilogram of the solvent. Let the weight of solute be w2 having molar mass M2 dissolved in w1 grams of solvent. Then molality can be given as: So , now, elevation boiling point is given by: Now if we rearrange the above equation ,we get
- 16. Definition of the symbols M2 = M.wt of the solute.g/mol W2= weight of the solute.gm W1=weight of the solvent. gm m= molality of the solution. Mol/Kg Kb = molal boiling point elevation constant, and it is a constant characteristic of the solvent. Its unite is (C°.kg/mol.).Kb depends only on nature of solvent and not on the solute.
- 17. Reference • Gelbspan, R., 2004. Boiling Point. Nation, 279(5), pp.24-26. • Schmidt, H.J., Kaufmann, B. and Treagust, D.F., 2009. Students’ understanding of boiling points and intermolecular forces. Chemistry Education Research and Practice, 10(4), pp.265- 272 • Pinarbasi, T., Sozbilir, M. and Canpolat, N., 2009. Prospective chemistry teachers’ misconceptions about colligative properties: boiling point elevation and freezing point depression. Chemistry Education Research and Practice, 10(4), pp.273-280. • Zaitseva, N., Dai, Z.R., Grant, C.D., Harper, J. and Saw, C., 2007. Germanium nanocrystals synthesized in high-boiling-point organic solvents. Chemistry of Materials, 19(21), pp.5174- 5178. Vancouver
- 18. Any Questions
- 19. Thanks