In a constant-pressure calorimeter, 70.0 mL of 0.300 M Ba(OH)2 was added to 70.0
ID: 916286 • Letter: I
Question
In a constant-pressure calorimeter, 70.0 mL of 0.300 M Ba(OH)2 was added to 70.0 mL of 0.600 M HCl. The reaction caused the temperature of the solution to rise from 21.73 °C to 25.82 °C. If the solution has the same density and specific heat as water, what is ?H for this reaction (per mole of H2O produced)? Assume that the total volume is the sum of the individual volumes.
In a constant-pressure calorimeter, 70.0 mL of 0.300 M Ba(OH2 was added to 70.0 mL of 0.600 M HCI The reaction caused the temperature of the solution to rise from 21.73 to 25.82 . If the solution has the same density and specific heat as water, what is AH for this reaction (per mole of H20 produced)? Assume that the total volume is the sum of the individual volumes. Number kJ/mol H,oExplanation / Answer
V = 70 ml
V = 70 ml
VT = 70*2 = 140 ml or 140 g of water
dT = 25.82-21.73 = 4.09
Q = m*cp*dT = 140*4.184*4.09= -2395.7584 J
note that this is for the whole reaction, we need per mol of H2O
find moles of H2O produced
Ba(OH)2 + 2 HCl ---> 2H2O + BaCl2
the ratios are stoichiometric...
find moles of HCl
mol Hcl = M*V = 70*0.6 = 42 mmol of HCl
1:1 ratio of HCl and H2O, therefore, expect 42 mmol of H2O
total mol = 42*10^-3
H = -Q/n = -2395.7584 /(42*10^-3) = -57041.866 J/mol H2O = -57.04 kJ/mol H2O