Please see Moodle for your assigned values! Potassium chlorate decomposes when h

Question

Please see Moodle for your assigned values! Potassium chlorate decomposes when heated yielding potassium chloride and oxygen gas. Write the balanced equation here: 2KClO_3 (s) rightarrow 2KCl(s) + 3O_2(g) You collect the oxygen gas over water. Insert your values of the barometric (total) pressure, temperature, and volume of gas collected here, (include units) barometric pressure temperature volume Determine the vapor pressure of water in your sample. What is the pressure of O_2 gas you collect? How many moles of O_2 gas did you collect? Give your gas here What is the density of your gas at STP?

Explanation / Answer

(a) I am not sure if any other data is given to you, but I am assuming that we are supposed to look up tables of values of vapour pressure of water at different temperatures to answer this part of the question. I looked up on the internet to find that at 5°C, the vapour pressure of water is 6.5 mmHg (ans).

(b) The vapour pressure of the oxygen gas collected = barometric pressure – vapour pressure of water = (762.0 – 6.5)mmHg = 755.5 mmHg.

© To calculate the moles of O2 gas collected, we assume ideal behaviour here and employ the equation of state, PV=nRT where P = pressure of the gas in atm; V = volume of the gas in L; n is the number of moles of the gas; R is the universal gas constant = 0.082 L-atm/mol.K and T = absolute temperature of the gas.

Here, P = (755.5 mmHg)/(760 mmHg/atm) = 0.994 atm

V = 70 mL = (70 mL/1000 mL)(1 L) = 0.07 L

T = (273 + 5) = 278K

We substitute these values of P,V,R and T. Therefore,

(0.9904 atm)(0.07 L) = n(0.082 L-atm/mol.K)(278K)

or, n = (0.9904)(0.07)/(0.082)(278) mole = 0.003 mol (ans)

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