Question

i am not sure is my answers on this lab is correct. i am confused as fo how to find the mass of solution and moles of H+ and OH-

Chem. 1A Thermochemistry Experiment 7 Data and Results: Part A M (HCI): Volume HCl(aq): h Initial Temperature: HO Reaction 2: Heat of Neutralization M(NaOH) lt 0.5 mL) Volume NaOH(aq): 22.0 " from plot) Final Temperature: 65 - D_10.5 mL) 29. 5 °C (from plot) AT (from plot) IM Mass of Solution: (show all calculations) 50. umxlg igator Ime moon mieltm Nutt sug tsug moin - 509 +509 msan tog Moles H:show all calculations) Moles OH":{show all calculations) 50g x Imola ODLOH 59.98 _moles moles OH AH experimental: (show all calculations) Whion am 9mxcxat mulon 100.9 X 44.184 Jlx' X 6.5 9=2719.65 E nd H. 2.71461J 02.17568 125 kJ/mol -2.2 + OH (49) -> H20(1) H o AH (theoretical): (see page 8) (show all calculations -285.9 -((-229.9)+00) -5600 kJ/mol Percent Error: (show all calculations) -2.2-(-560) -56 XIN 96% W 2120

Chem 1A Thermochemistry Experiment 7 Reaction 2: Heat of Neutralization

Answer 1

Hi there, everything has been done by you and impressive, but only small mistake i have found at moles OH-

moles = volume in L x molarity

since both have 1.0 M concentration and volume also same = 50.0 mL

so moles [H+] = moles [OH-] = 50.0 mL x 10^-3 L x 1.0 M = 0.05 mol

ΔHrxn = -q / mol

mass of solution = 50 g + 50 g = 100 g (since we assume solution density as 1 g/mL

q = mass of solution in g x specific heat capacity of water x difference in temperature = 100 g x 4.184 J/g.0C x 6.5 0C = 2719.6 J

q = 2719.6 J = 2.7196 kJ since 1 kJ = 1000 J

ΔHrxn = -q / mol = 2719.6 J / 0.05 = 54392 J = 54.392 kJ/mol

ΔHrxn = -54.392 kJ/mol (negative sign due to exothermic reaction)

ΔHtheoretical = [H2O(l)] - [(H+) + (OH-)] = [ -285.8 ] - [0 - 230] = -55.8 kJ/mol

ΔHtheoretical = -55.8 kJ/mol

percent error = (|experimental - theoretical| / theoretical ) x 100% = [(-54.392 -(-55.8) / -55.8] x 100% = -2.52

but we express percent error in magnitude, so

percent error = 2.52%

Hope this helped you!

Thank You So Much!

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