Gravimetric Determination of Calcium
Phuong Pham
Prof. Johnson
Lab 3 Gravimetric determination of Calcium as CaC2O4.H2O
Feb, 27, 2014
I. Objective:
The purpose of this lab is to determine how well gravimetric method measures the calcium level in a solution of known calcium concentration.
II. Method:
a) Overview:
In this lab we will prepare 25 mL known concentration Calcium solutions. Then we will use Gravimetric method to determine the concentration of Calcium in each solution to figure out how well this method is. As we know, Ca2+ can form precipitation with oxalate in form CaC2O4. H2O in basic solution. So, in this method we will slowly precipitate all Ca2+ in the solution with C2O42- in acidic HCl solution and slowly raise pH of the solution by thermal decomposition of Urea. Then, we will filter and dry the precipitation from the solution and mass the precipitation. After all we will calculate to figure out how much Ca in the precipitation, then compare with the expected Ca amount.
b) Procedure:
The experiment is done in Room condition.
We are prepared with standard mass of Gooch crucible so we can skip drying crucible process.
In this experiment, we transfer 25mL of Ca2+ from 500mL solution of 8.9037g Calcium Carbonate (CaCO3) in 0.46M HCl into a 250mL beaker, then add 75mL HCl 0.1M acid into thebeaker. Next, we add 8 drops methyl red indicator to the beaker. After that, we add 25mL ammonium oxalate to the beaker and mix the solution. Mass around 15 g urea and add them to the beaker. (our amounts of urea are 15.048g (added in crucible A) and 15.099g (added in crucible B).While one of us is preparing another solution in another 250mL beaker with the same process, the other will boil the 1st beaker until the solution turn clear completely, which takes around 40 mins. After the 1st solution is done with the boiling process, one of us filter the precipitation from the 1st beaker with Gooch crucible A, which takes around 30 to 40 mins, the other will boil the second solution. When the
Prof. Johnson
Lab 3 Gravimetric determination of Calcium as CaC2O4.H2O
Feb, 27, 2014
I. Objective:
The purpose of this lab is to determine how well gravimetric method measures the calcium level in a solution of known calcium concentration.
II. Method:
a) Overview:
In this lab we will prepare 25 mL known concentration Calcium solutions. Then we will use Gravimetric method to determine the concentration of Calcium in each solution to figure out how well this method is. As we know, Ca2+ can form precipitation with oxalate in form CaC2O4. H2O in basic solution. So, in this method we will slowly precipitate all Ca2+ in the solution with C2O42- in acidic HCl solution and slowly raise pH of the solution by thermal decomposition of Urea. Then, we will filter and dry the precipitation from the solution and mass the precipitation. After all we will calculate to figure out how much Ca in the precipitation, then compare with the expected Ca amount.
b) Procedure:
The experiment is done in Room condition.
We are prepared with standard mass of Gooch crucible so we can skip drying crucible process.
In this experiment, we transfer 25mL of Ca2+ from 500mL solution of 8.9037g Calcium Carbonate (CaCO3) in 0.46M HCl into a 250mL beaker, then add 75mL HCl 0.1M acid into thebeaker. Next, we add 8 drops methyl red indicator to the beaker. After that, we add 25mL ammonium oxalate to the beaker and mix the solution. Mass around 15 g urea and add them to the beaker. (our amounts of urea are 15.048g (added in crucible A) and 15.099g (added in crucible B).While one of us is preparing another solution in another 250mL beaker with the same process, the other will boil the 1st beaker until the solution turn clear completely, which takes around 40 mins. After the 1st solution is done with the boiling process, one of us filter the precipitation from the 1st beaker with Gooch crucible A, which takes around 30 to 40 mins, the other will boil the second solution. When the