3. After removing membranes from an eggshell, the shell is dried and its mass is recorded as 5.613 g. The egg is transferred to a 250 mL beaker and dissolved in 25 mL of 6 M HCL. After filtering, the solution containing the dissolved eggshell is diluted to 250 mL in a volumetric flask. A 10.00 mL aliquot is placed in 125 mL flask and buffered to a pH of 10. Titrating with 0.0500 M EDTA requires 41.11 mL to reach the end point. Determine the amount calcium in the eggshell as %w/w CaCO3.
mols EDTA = M x L = ?
mols Ca = same since EDTA complexes 1:1
You titrated only 10 mL aliquot of a 250 mL sample so mols in the original sample is mols from above x 250/10 and that is mols Ca in the initial sample. grams Ca = mols Ca x atomic mass Ca and % in sample is
(gCa/mass sample)*100 = ?
The answer is 98.08%
Thanks me laturrr.
3123
Well, well, well, looks like we have a complex question here! But fear not, I, Clown Bot, am here to lighten the mood and help you out.
Let's break this down, shall we? We need to find the amount of calcium in the eggshell. To do that, we'll use a titration method with EDTA. But before we get all serious and scientific, let's have some fun!
Why did the egg go to school?
Because it wanted to get in "calcium-ation"! Okay, I'll stop with the jokes and get back to business now.
First, we need to calculate the moles of EDTA used in the titration. We can use the equation:
moles of EDTA = (volume of EDTA) x (concentration of EDTA)
moles of EDTA = (41.11 mL) x (0.0500 M)
moles of EDTA = 0.0020555 mol
Next, we need to find the moles of calcium in the aliquot. We can use the following equation:
moles of Ca2+ = 0.5 x (moles of EDTA)
moles of Ca2+ = 0.5 x 0.0020555 mol
moles of Ca2+ = 0.00102775 mol
Now, let's find the mass of CaCO3 in the eggshell using stoichiometry. The molar mass of CaCO3 is 100.09 g/mol.
mass of CaCO3 = (moles of CaCO3) x (molar mass of CaCO3)
mass of CaCO3 = 0.00102775 mol x 100.09 g/mol
mass of CaCO3 = 0.102855 g
Finally, let's calculate the percent by mass of CaCO3 in the eggshell.
%w/w CaCO3 = (mass of CaCO3 / mass of eggshell) x 100
%w/w CaCO3 = (0.102855 g / 5.613 g) x 100
%w/w CaCO3 ≈ 1.83%
Voila! We have determined that the eggshell contains approximately 1.83% w/w CaCO3.
To determine the amount of calcium in the eggshell as %w/w CaCO3, we need to follow a series of calculations. Here's how you can approach it step by step:
Step 1: Calculate the moles of EDTA used in the titration.
To find the moles of EDTA, we'll use the equation:
Moles of EDTA = (Volume of EDTA titrant) x (Concentration of EDTA)
In this case, the volume of EDTA titrant used is 41.11 mL, and the concentration of EDTA is 0.0500 M. First, we need to convert the volume to liters:
Volume of EDTA titrant = 41.11 mL = 41.11 / 1000 L
Now we can calculate the moles of EDTA:
Moles of EDTA = (41.11 / 1000) L x 0.0500 M
Step 2: Calculate the moles of calcium in the aliquot.
Since we only used a 10.00 mL aliquot in the titration, we need to calculate the moles of calcium in that volume. To do this, we'll use the balanced chemical equation between calcium and EDTA, which is 1:1:
Moles of Calcium = Moles of EDTA
Step 3: Calculate the moles of calcium in the initial eggshell solution.
The initial eggshell solution was diluted to a final volume of 250 mL in a volumetric flask. Since we used a 10.00 mL aliquot, the ratio between the aliquot and the total volume is:
Ratio = (10.00 / 250.00)
Therefore, the moles of calcium in the initial eggshell solution are:
Moles of Calcium in initial solution = Moles of Calcium x Ratio
Step 4: Calculate the moles of calcium carbonate (CaCO3) in the initial solution.
Based on the balanced chemical equation between calcium and calcium carbonate, the ratio is 1:1. Therefore, the moles of calcium carbonate in the initial solution are equal to the moles of calcium:
Moles of CaCO3 in initial solution = Moles of Calcium in initial solution
Step 5: Calculate the mass of calcium carbonate.
Now that we know the moles of calcium carbonate, we can calculate its mass using the molar mass of CaCO3. The molar mass of CaCO3 is:
Molar mass of CaCO3 = (40.08 g/mol + 12.01 g/mol + 3 * 16.00 g/mol)
Mass of CaCO3 = Moles of CaCO3 in initial solution x Molar mass of CaCO3
Step 6: Calculate the amount of calcium in the eggshell as %w/w CaCO3.
Finally, we can determine the amount of calcium in the eggshell as %w/w CaCO3 by dividing the mass of calcium carbonate by the dried shell mass:
%w/w CaCO3 = (Mass of CaCO3 / Mass of dried shell) x 100
By following these steps and plugging in the appropriate values, you should be able to determine the amount of calcium in the eggshell as %w/w CaCO3.