Tungsten trioxide (WO3) has a rich yellow color and is often used as a pigment in ceramics and paints. In order to test a ceramic vase for its WO3 content, a 10.19 g sample of the vase was ground and reduced with Pb(Hg) to convert any WO3 to W3 .

The resulting W3 was transferred to 500.0 mL of 1.00 M HCl. A 100.00 mL aliquot of the HCl solution required 10.13 mL of 0.08840 M potassium permanganate (KMnO4) to reach the purple endpoint. A blank required 0.18 mL. Determine the percent WO3 in the ceramic sample.

To determine the percent WO3 in the ceramic sample, we need to perform a series of calculations using the given information. Here are the steps to follow:

Step 1: Calculate the number of moles of KMnO4 used in the titration:
First, we need to calculate the number of moles of KMnO4 used in the titration. We have the volume and concentration of KMnO4:
Volume of KMnO4 used = 10.13 mL - 0.18 mL = 9.95 mL = 0.00995 L
Number of moles of KMnO4 used = Volume x Concentration = 0.00995 L x 0.08840 M

Step 2: Calculate the number of moles of WO3 in the aliquot:
The reaction between KMnO4 and WO3 is as follows:
5WO3 + 2KMnO4 + 16HCl -> 5WO2Cl2 + 2MnCl2 + 8H2O + 2KCl
From the balanced equation, we can see that the stoichiometric ratio between WO3 and KMnO4 is 5:2.
Using this ratio, we can calculate the number of moles of WO3 in the aliquot:
Number of moles of WO3 = (5/2) x Number of moles of KMnO4 used

Step 3: Calculate the number of moles of WO3 in the entire HCl solution:
Since we used a 100.00 mL aliquot of the HCl solution, we need to calculate the number of moles of WO3 in the entire 500.0 mL solution:
Number of moles of WO3 in the entire solution = (5/2) x Number of moles of KMnO4 used x 5

Step 4: Calculate the number of moles of WO3 in the original ceramic sample:
We started with a 10.19 g sample and converted WO3 to W3 :
The molar mass of WO3 = 231.84 g/mol
Number of moles of WO3 in the original sample = Mass of sample / Molar mass of WO3

Step 5: Calculate the percent WO3 in the ceramic sample:
Finally, we can calculate the percent WO3 in the ceramic sample:
Percent WO3 = (Number of moles of WO3 in the original sample / Number of moles of WO3 in the entire solution) x 100

By following these steps and plugging in the given values, you should be able to calculate the percent WO3 in the ceramic sample.

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