2. (3) Corey and Nicole performed the same experiment that you did last week. Th

Question

2. (3) Corey and Nicole performed the same experiment that you did last week. They collected the following data. Calculate the value of R from their data. MW of O2 = 32.0 Barometric Pressure: 756 torr Temperature: 22 C Vapor Pressure of H2O at 22°C: 20.0 torr mass of tube+KCIO, before heating: 8.3078 g mass of tube+ contents after heating: 8.2585 g Determine their 96 error. 1 liter = 1000 ml; Initial buret reading: 0.1 ml Final buret reading: 38.7 m heat Unbalanced Reaction: KCIO3(s)" > KCl(s) + O2(g)

Explanation / Answer

% error can be calculated via

% R error = (Rtheoretical- Rcalculated)/Rtheoretical*100%

Rtheoretical = 62.36367 torrL/molK

then

Apply Ideal Gas Law,

PV = nRT

where

P = absolute pressure

V = total volume of gas

n = moles of gas

T = absolute Temperature

R = ideal gas constant

then, we need

T = 22°C = 22+273 = 295 K

V = 38.7-0.1 = 38.6 mL = 38.6*10^-3 L

Pgas = Patm - Pvap = 756-20 = 736 torr

now...

mass of O2 = 8.3078-8.2585 = 0.0493

mol of O2 = mass of O2/MW of O2 = (0.0493) /(32) = 0.00154

then

R = PV/(nT)

R = (736)(38.6*10^-3)/(295 * 0.00154) = 62.534

%error = (62.36367 -62.534)/62.36367 *100 = 0.273%

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