Given the data summarized in the figures below answer the following questions. B

Question

Given the data summarized in the figures below answer the following questions. Based on the data summarized above, write the complete balanced thermo chemical equations for the two reactions investigated in Lab 3 (note that metals and HCI produce hydrogen gas and an while metal oxides and HCl produce water and aqueous salt Use the above information and the enthalpy of formation of water to determine the en of formation of MgO. Based on this value, how much heat is released when 10.45g of magnesium oxide is formed?

Explanation / Answer

Q5.

a)

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

MgO(aq) + 2 HCl(aq) = H2O(aq) + MgCl2(aq) + heat

b)

Hrxn = Hprod - Hreact

Hrxn = H-H2O + H-MgCl2 - (H-MgO + 2*H-HCl)

assume 1 mol of MgO produced:

y = -138000x

Q(J) = -138000*1 = -138000 J/mol = 138.0 kJ/mol

138.0 = -285.8 + -641.8- (H-MgO + 2*-167.2)

H-MgO = 138.0 +285.8+641.8 -2*167.2 = 731.2 kJ/mol

so

mol of MgO = mass/MW = 10.45/40.3044 = 0.25927

so

Q = n*Hrxn = 0.25927*731.2 = 189.578kJ/mol will be relesaed

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