Week 1: Chemical Analysis
VCE Chemistry Week 1 - Chemical Analysis (1)
Horizen Education February 8, 2013
1
1.1
Review: Gravimetric and Volumetric Analysis
Gravimetric Analysis
Solubilities Always soluble: Usually soluble: Exceptions:
Na+ , K+ , NO3− , CH3 COO− , NH+ 4 Cl− , I− , Br−
i. Sodium carbonate and Silver nitrate
ii. Iron (II) sulfate and Lead (II) nitrate
iii. Sodium nitrate and Nickel sulfate
iv. Potassium hydroxide and Copper (II) nitrate
v. Sodium sul de and Cadmium sulfate
Ho
Write down the ionic chemical equation when the following pairs of solutions are mixed together. (Take note of their solubilities of the products formed)
Question 1.
riz
Remember that all ionic compounds are soluble to an extent; those classi ed …show more content…
Ed
6
b) What amount of sulfuric acid, in mol, was needed to reach the endpoint?
uc
a) Write an equation between the metal carbonate and sulfuric acid.
ati
A solution of a metal carbonate with chemical formula X2 CO3 was prepared by dissolving 2.80g of the solid in 250mL of water. 20.00mL aliquots were titrated with a 0.150M H2 SO4 solution, using methyl orange as the indicator. The average titre was found to be 10.8mL. (Source: Heinemann Chemistry)
on
Ka
Strong acid + strong base: equivalence pH 7
Strong acid + weak base: equivalence pH 3-6
Strong base + weak acid: equivalence pH 8-11
Weak base + weak acid: equivalence unknown (use back titration for analysis)
i. A larger volume of NaOH(aq) is needed to reach the equivalence point in the titration of HNO3
v. The titration curves will essentially be the same after passing the equivalence point vi. Methyl red would be a suitable indicator for both titrations
1.3 Back Titration
Some acids and bases are too weak to analyse using conventional methods. These weak acids and bases must undergo a process called back titration to determine their …show more content…
Limestone is known to contain calcium carbonate as an impurity. A sample of limestone was analysed using back titration. A 1.0g sample of limestone was weighed and made into a 50.0mL solution in a conical ask. An excess of 0.395M hydrochloric acid, exactly 50.0mL, was added and allowed to fully react with the CaCO3 . After this reaction, the remaining HCl was titrated with a standard 0.0489M solution of Sodium Hydroxide. The titre was found to be 22.32mL. (Source: Heinemann
Horizen Education February 8, 2013
1
1.1
Review: Gravimetric and Volumetric Analysis
Gravimetric Analysis
Solubilities Always soluble: Usually soluble: Exceptions:
Na+ , K+ , NO3− , CH3 COO− , NH+ 4 Cl− , I− , Br−
i. Sodium carbonate and Silver nitrate
ii. Iron (II) sulfate and Lead (II) nitrate
iii. Sodium nitrate and Nickel sulfate
iv. Potassium hydroxide and Copper (II) nitrate
v. Sodium sul de and Cadmium sulfate
Ho
Write down the ionic chemical equation when the following pairs of solutions are mixed together. (Take note of their solubilities of the products formed)
Question 1.
riz
Remember that all ionic compounds are soluble to an extent; those classi ed …show more content…
Ed
6
b) What amount of sulfuric acid, in mol, was needed to reach the endpoint?
uc
a) Write an equation between the metal carbonate and sulfuric acid.
ati
A solution of a metal carbonate with chemical formula X2 CO3 was prepared by dissolving 2.80g of the solid in 250mL of water. 20.00mL aliquots were titrated with a 0.150M H2 SO4 solution, using methyl orange as the indicator. The average titre was found to be 10.8mL. (Source: Heinemann Chemistry)
on
Ka
Strong acid + strong base: equivalence pH 7
Strong acid + weak base: equivalence pH 3-6
Strong base + weak acid: equivalence pH 8-11
Weak base + weak acid: equivalence unknown (use back titration for analysis)
i. A larger volume of NaOH(aq) is needed to reach the equivalence point in the titration of HNO3
v. The titration curves will essentially be the same after passing the equivalence point vi. Methyl red would be a suitable indicator for both titrations
1.3 Back Titration
Some acids and bases are too weak to analyse using conventional methods. These weak acids and bases must undergo a process called back titration to determine their …show more content…
Limestone is known to contain calcium carbonate as an impurity. A sample of limestone was analysed using back titration. A 1.0g sample of limestone was weighed and made into a 50.0mL solution in a conical ask. An excess of 0.395M hydrochloric acid, exactly 50.0mL, was added and allowed to fully react with the CaCO3 . After this reaction, the remaining HCl was titrated with a standard 0.0489M solution of Sodium Hydroxide. The titre was found to be 22.32mL. (Source: Heinemann