Im stuck on this one! please help! chemistry...?

Question

Potassium perchlorate, KCIO4, decomposes on heating to form potassium chloride and elemental oxygen.

a. Write a balanced molecular equation for the thermal decomposition of potassium perchlorate.


Using a setup like this experiment, the following data were collected:

weight of sample before heating= 1.2460 g
weight of sample after heating= 0.9265 g
volume of water displaced= 258 mL
atmospheric pressure= 748.9 torr
water temperature= 26.0 degrees Celsius

b. What is the percent KCIO4 in the sample being heated?

c. What volume would this sample of oxygen occupy if collected at standard temperature and pressure?

d. What is the molar volume at STP of O2 according to these data?

Answer 1

a. KClO4 --> KCl + 2O2

b. If n mol is the quantity of KClO4 in the sample then the quantity of O2 is 2n mol. But:

mass of O2 = 1.2460 - 0.9265 = 0.3195 g of O2, so:

2n = m/Mr = 0.3195/32 = 0.01 mol (approx) where Mr = 32 the molar mass of O2. So:

n = 0.01/2 = 0.005 mol of KClO4

m = n*Mr = 0.005 x 138.5 = 0.692 g of KClO4, where Mr = 138.5 the molar mass of KClO4

So the percent of KClO4 in the sample is:

0.692 x 100/1.2460 = 55.5% (approx).

c. V = nO2 * 22.4 = 0.01 * 22.4 = 0.224 L or 224 mL

d. p1*V1/T1 = p2*V2/T2, so:

V2 = p1*V1*T2/(T1*p2)

Substituting: p1 = 748.9 torr, V1 = 0.258 L, T2 = 273 K, T1 = 273 + 26 = 299 K, p2 = 760 torr, we get:

V2 = 0.2321 L of O2 in STP.

Vm = V2/n = 0.2321/0.01 = 23.21 L/mol, where Vm the molar volume in STP and n the quantity of O2 in moles.

Answer 2

KClO4 -------> KCl + 2O2
for the rest, data is insufficient....volume of water? huh? where, when, what dimensions of the apparatus? water is displaced by oxygen, but what are the dimensions of the enclosing space?
srry. cant answer this. give some more details plz

Answer 3

sorry the above answer is correct hence with drawing my answer