Ideal Gas Law, PV- nRT Name Instructor (Unless otherwise noted, 2 pts. for cach

Question

Ideal Gas Law, PV- nRT Name Instructor (Unless otherwise noted, 2 pts. for cach blank) Molarity of HCI (M) (Ipt. each): Volume of HCl (mL): Mass of Mg (gram): *Volume of gas before placing in Section Partner Data, Trial 1 Data, Trial 2 3.S 26.0-L 0351 3b3 Equalization Chamber (mL) (I pt.) (*This value NOT used in calculations below) Volume of gas after placing in Equalization Chamber (mL): Barometric Pressure (mm Hg): Temperature (°C): Write the balanced overall equation for the reaction of magnesium and HCl to form hydrogen 20.0 20.0t gas and the magnesium salt (2 pts): 5 Cs) Mole of Mg reacted Mole of H2 formed (based on the stoichiometric equation for the reaction) Vapor Pressure of water from curve in mmig: Pressure of H2 from Dalton's Law in mmHg: Pressure of H2 in atm Volume of H2 in liter (Using volume measured in Equalization Chamber) Temperature in Kelvin Calculation of R (6 pts. each) Percent error Average R = 63

Explanation / Answer

Trial 1:

Moles of Mg reacted = Mass of Mg/ molar mass of Mg = 0.036 g/ 24.305 g/mol = 1.48 X 10-3 moles

From the reaction:

Mg (s) + 2HCl(aq) ----------------> MgCl2(aq) + H2(g)

Moles of Mg = moles of H2(g)

moles of H2(g), n = 1.48 X 10-3 moles

pressure of H2 = atmospheric pressure - vapor pressure of water at 20 deg

pressure of H2 in mm Hg = 731.00 mm Hg - 17.5 mm Hg = 713.5 mm Hg

pressure of H2 in atm (p) = 713.5/760 atm = 0.939 atm

volume of H2 in L (v) = (41.6 -41.0) X 10-3 L = 0.6 X 10-3 L

Temperature (in K) = 20 deg c = 20+278 = 298K

R = PV/nT = (0.939 atm * 0.6 X 10-3 L)/(1.48 X 10-3 mol * 298 K) = 0.001277 L.atm/mol.K

Actual value of R = 0.08205 L.atm/mol.K

% error = (0.08205 - 0.01277)/0.08205 * 100% = 84.4 %

Trial 2:

Moles of Mg reacted = Mass of Mg/ molar mass of Mg = 0.035 g/ 24.305 g/mol = 1.44 X 10-3 moles

From the reaction:

Mg (s) + 2HCl(aq) ----------------> MgCl2(aq) + H2(g)

Moles of Mg = moles of H2(g)

moles of H2(g), n = 1.44 X 10-3 moles

pressure of H2 = atmospheric pressure - vapor pressure of water at 20 deg

pressure of H2 in mm Hg = 731.00 mm Hg - 17.5 mm Hg = 713.5 mm Hg

pressure of H2 in atm (p) = 713.5/760 atm = 0.939 atm

volume of H2 in L (v) = (40.4 -39.8) X 10-3 L = 0.6 X 10-3 L

Temperature (in K) = 20 deg c = 20+278 = 298K

R = PV/nT = (0.939 atm * 0.6 X 10-3 L)/(1.44 X 10-3 mol * 298 K) = 0.001313 L.atm/mol.K

Actual value of R = 0.08205 L.atm/mol.K

% error = (0.08205 - 0.0130)/0.08205 * 100% = 84.2 %

Average of R from both trials = 0.0130 L.atm/mol.K

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