Please help me solve the following problem. I am looking for step by step instru
ID: 892539 • Letter: P
Question
Please help me solve the following problem. I am looking for step by step instructions so that I can understand this procedure for further exams. Thanks in advance.
Bath Temperature: 34.0 degrees C
Buret Reading Vol of O2 Time (s)
4.5 0 0 sec
6.5 2.0 10 sec
8.5 4.0 36 sec
10.5 6.0 87 sec
12.5 8.0 119 sec
14.5 10.0 150 sec
16.5 12.0 178 sec
18.5 14.0 203 sec
20.5 16.0 228 sec
22.5 18.0 256 sec
Total Volume of O2 collected is 18.0 mL
Barametric Pressure 760 mm Hg
Vapor pressure of water at bath temperature is 39.9 mm Hg
Slope: 0.0658
Using the ideal-gas law, calculate the moles of O2 collected _____________ mol O2.
Explanation / Answer
Total volume of O2 collected, V = 18.0 mL = 18.0 mL x (1L / 1000 mL) = 0.0180 L
Total Barametric Pressure reading (Pressure due to both O2 and water vapor) = 760 mm Hg
Vapor pressure of water = 39.9 mm Hg
Hence pressure due to O2 = Total Barametric Pressure - Vapor pressure of water = (760 - 39.9) mmHg
= 720.1 mm Hg = 720.1 mm Hg x (0.00131579 atm / 1 mm Hg) = (720.1 x 0.00131579) atm
Temperature, T = 34.0 DegC = 34.0 + 273 K = 307 K
Here we calculated V in terms of L and P in terms of atm, be cause we can use the value of R equals to 0.0821 L.atm.mol-1K-1 .
Now applying ideal gas equation, PV = nRT
=> n = PV / RT = [(720.1 x 0.00131579) atm x 0.0180 L] / (0.0821 L.atm.mol-1K-1x307K)
= 6.77x10-4 mol (answer)