Assignment: To be submitted a. What are the different titration errors associated with the use of chemical indica
Posted: Wed Jul 06, 2022 11:28 am
Assignment: To be submitted
a. What are the different titration errors associated with the use of chemical indicators? Describe how these errors can be minimized or avoided.
b. Why are chemical indicators used only in the form of dilute solutions?
II. Kjedahl method is the most common method for determining organic nitrogen.
a. What are the different steps involved in this method of analysis? Describe briefly each step.
b. Can this method be used to analyze protein in serum? Explain briefly.
c. What other methods can be applied to determine total serum protein. Describe this method and compare this to Kjedahl method.
III. Solve the following problems.1. A 0.4512g sample of primary standard grade Na2CO3 required 36.44mL of an H2SO4 solution to reach the end point in the reaction:
Na2CO3 + 2HCl → 2NaCl + H2O + CO2
What is the molarity of the H2SO4?
2. How many mL of 0.25M solution of H2SO4 will react with 10mL of 0.25M solution of NaOH?
3. What weight of pure Na2CO3 should be taken so that about 25mL of approximately 0.1M HCl will be used in a standardization titration using methyl red end point?
4. A 0.91g sample of a wheat flour was analyzed by the Kjedahl method. The NH3 formed was distilled into a 50mL of 0.05M HCl, a 7.46mL back-titration with 0.05M NaOH was required. Calculate the % of protein in the flour.
5. A 0.527g sample of a mixture containing Na2CO3, NaHCO3, and inert impurities is titrated with 0.109M HCl requiring 15.7mL to reach the phenolphthalein end point. What is the % Na2CO3 and NaHCO3 in the mixture?
a. What are the different titration errors associated with the use of chemical indicators? Describe how these errors can be minimized or avoided.
b. Why are chemical indicators used only in the form of dilute solutions?
II. Kjedahl method is the most common method for determining organic nitrogen.
a. What are the different steps involved in this method of analysis? Describe briefly each step.
b. Can this method be used to analyze protein in serum? Explain briefly.
c. What other methods can be applied to determine total serum protein. Describe this method and compare this to Kjedahl method.
III. Solve the following problems.1. A 0.4512g sample of primary standard grade Na2CO3 required 36.44mL of an H2SO4 solution to reach the end point in the reaction:
Na2CO3 + 2HCl → 2NaCl + H2O + CO2
What is the molarity of the H2SO4?
2. How many mL of 0.25M solution of H2SO4 will react with 10mL of 0.25M solution of NaOH?
3. What weight of pure Na2CO3 should be taken so that about 25mL of approximately 0.1M HCl will be used in a standardization titration using methyl red end point?
4. A 0.91g sample of a wheat flour was analyzed by the Kjedahl method. The NH3 formed was distilled into a 50mL of 0.05M HCl, a 7.46mL back-titration with 0.05M NaOH was required. Calculate the % of protein in the flour.
5. A 0.527g sample of a mixture containing Na2CO3, NaHCO3, and inert impurities is titrated with 0.109M HCl requiring 15.7mL to reach the phenolphthalein end point. What is the % Na2CO3 and NaHCO3 in the mixture?