E) One student used Mg instead of NaHCO, in the reaction Below is the data sheet
ID: 701797 • Letter: E
Question
E) One student used Mg instead of NaHCO, in the reaction Below is the data sheet that he did not complete. Help this student to complete this data theet and shon all the calculations in order to get credits. ( atm-760 mm Hg 1 nch 3,54 cm The reaction equation :-Mg Is1+-Hci taq/>-edn/--Mech imi (Note: tho rection equation is not balanced, balance this equation over here Determination Mass of Mg, Number of moles of Mg Number of moles of H Volume of gas, ml Barometric pressure, ine inch H Temperature Vapor pressure of water Table: vapor pressure of waerus temperatures Temperature Pressure 20 21 rc mmi 175 18.7 19.8 21.1 23Explanation / Answer
Moles of Mg = mass of Mg/molecular weight
= 0.076g / 24.3 g/mol
= 0.003127 mol
Balanced equation
Mg(s) + 2 HCl(aq) --> MgCl 2(aq) + H2(g)
From the stoichiometry of the reaction
Moles of H2 produced = moles of Mg consumed = 0.003127 mol
Volume of gas = 70.4 mL x 1L/1000 mL = 0.0704 L
Barometric pressure
= 28.50 inch Hg x 2.54cm/inch x 10mm/cm
= 723.9 mmHg
Temperature in K = 22.5 + 273.15 = 295.65 K
Vapor pressure of water at 22.5°C
Pvapor = 19.8 + (21.1 - 19.8)(22.5 - 22)
= 20.45 mmHg
Corrected H2 pressure = barometric - vapor pressure
= 723.9 - 20.45
= 703.45 mmHg
= 703.45 mmHg x 1atm/760mmHg
= 0.9256 atm
From the ideal gas equation
R = PV/nT
=( 0.9256 atm x 0.0704 L) / (0.003127 mol x 295.65 K)
= 0.07048 L-atm/mol-K
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