@DrBob222
I am stuck,
x=1.590 g of k2CO3=> x+y=2.118
1.590+y=2.118 => y=0.528 g of KHCO3
then 0.528 g to moles
2x+0.00527 mole=0.0230 mol => x=1.225 g of KCO3
A 2.118 g sample of a solid mixture containing only potassium carbonate ( MM=138.2058 g/mol ) and potassium bicarbonate ( MM=100.1154 g/mol ) is dissolved in distilled water. A volume of 30.20 mL of a 0.763 M HCl standard solution is required to titrate the mixture to a bromocresol green end point. Calculate the weight percent of potassium carbonate and potassium bicarbonate in the mixture.
It isn't clear to me what you've done but if you have solved the two equations and your answer for x is 1.590 and for y is 0.528 then then you've done the hard part and determined the mass of K2CO3 and the mass of KHCO3.The next step is to convert the mass of each carbonate to mass percent and that's done this way.
% K2CO3 = (1.590/2.118)*100 = ?
% KHCO3 = (0.528/2.118)*100 = ?
To calculate the weight percent of potassium carbonate (K2CO3) and potassium bicarbonate (KHCO3) in the mixture, you need to perform a series of calculations. Here's how you can approach it:
1. Start by determining the number of moles of HCl used in the titration:
- Volume of HCl solution = 30.20 mL = 0.03020 L
- Concentration of HCl solution = 0.763 M
- Moles of HCl = Concentration x Volume = 0.763 M x 0.03020 L = 0.023036 mol
2. From the balanced chemical equation between HCl and K2CO3, you know that 2 moles of HCl react with 1 mole of K2CO3.
3. Next, calculate the moles of K2CO3 in the mixture:
- Moles of K2CO3 = 0.023036 mol / 2 = 0.011518 mol
4. Now, determine the moles of KHCO3 in the mixture:
- Moles of KHCO3 = Moles of K2CO3 (since x+y = 2.118 g and y = 0.528 g, x = 1.590 g)
5. Convert the moles of KHCO3 to grams:
- Moles of KHCO3 x Molar mass of KHCO3 = Mass of KHCO3 in grams
- Moles of KHCO3 = 0.528 g / Molar mass of KHCO3
6. Calculate the weight percent of K2CO3 and KHCO3 in the mixture:
- % weight of K2CO3 = (Mass of K2CO3 / Total mass of the mixture) x 100
- % weight of KHCO3 = (Mass of KHCO3 / Total mass of the mixture) x 100
By plugging in the values obtained from the previous steps into the respective formulas, you can calculate the weight percent of potassium carbonate and potassium bicarbonate in the mixture.