a mixture of 39.8g containing potassium chloride and potassium trioxochlorate (v) upon heating, the residue weighed 28.7g what is the percentage mass of potassium chloride in the residue?
2KClO3 ==> 2KCl + 3O2
mass O2 released = 39.8-28.7 = 11.10g
mols O2 released = grams/molar mass
Using the coefficients in the balanced equation, convert mols O2 to mols KClO3.
Now convert mols KClO3 to grams KClO3. That's g KClO3 = mols KClO3 x molar mass KClO3. grams KClO3 = x
(% KClO3 in the original sample) = (x g KClO3/mass mixture)* 100 = ?
To find the percentage mass of potassium chloride in the residue, you need to determine the masses of potassium chloride and potassium trioxochlorate (V) separately.
First, subtract the mass of the residue (28.7g) from the initial mass of the mixture (39.8g) to find the mass of the substances that were lost during heating:
Mass lost = Initial mass of mixture - Mass of residue
Mass lost = 39.8g - 28.7g = 11.1g
Next, calculate the mass of potassium chloride by taking into account its molar mass and the molar ratio between potassium chloride and the lost mass:
Mass of potassium chloride = Mass lost × (Molar mass of potassium chloride / (Molar mass of potassium chloride + Molar mass of potassium trioxochlorate (V)))
The molar mass of potassium chloride (KCl) is approximately 74.55 g/mol, and the molar mass of potassium trioxochlorate (V) (KClO3) is approximately 122.55 g/mol.
Mass of potassium chloride = 11.1g × (74.55g/mol / (74.55g/mol + 122.55g/mol))
Mass of potassium chloride = 11.1g × (74.55g/mol / 197.1g/mol)
Mass of potassium chloride ≈ 4.16g
Finally, calculate the percentage mass of potassium chloride in the residue by dividing the mass of potassium chloride by the mass of the residue and multiplying by 100:
Percentage mass of potassium chloride = (Mass of potassium chloride / Mass of residue) × 100
Percentage mass of potassium chloride = (4.16g / 28.7g) × 100
Percentage mass of potassium chloride ≈ 14.5%
Therefore, the percentage mass of potassium chloride in the residue is approximately 14.5%.