1) When 0.119 g of Zn(s) is combined with enough HCl to make 51.6 mL of solution
ID: 906000 • Letter: 1
Question
1) When 0.119 g of Zn(s) is combined with enough HCl to make 51.6 mL of solution in a coffee-cup calorimeter, all of the zinc reacts, raising the temperature of the solution from 22.4 C to 23.9 C. Find Hrxn for this reaction as written. (Use 1.0 g/mL for the density of the solution and 4.18 J/gC as the specific heat capacity.)
2)Calculate Hrxn for the following reaction:
CaO(s)+CO2(g)CaCO3(s)
Use the following reactions and given H values:
Ca(s)+CO2(g)+12O2(g)CaCO3(s), H= -812.8 kJ
2Ca(s)+O2(g)2CaO(s), H= -1269.8 kJ
Explanation / Answer
1)
total volume of solution = 51.6 ml
solution density = 1 g/mm
solution mass = density x volume = 1 x 51.6 = 51.6g
q = m Cp dT
= 51.6 x 4.184 x (23.9-22.4)
= 323.84 J
moles of Zn = 0.119 / 65.38 = 1.82 x 10^-3
1 mol ----------------> 323.84 J
1.82 x 10^-3 mol -------------> 323.84 x 1.82 x 10^-3 = 0.589 J
DHrxn = 5.89 x 10^-4 kJ/mol
2)
Calculate Hrxn for the following reaction:
CaO(s)+CO2(g)CaCO3(s)
Ca(s) + CO2(g) + 1/2 O2(g)------------------>CaCO3(s), H= -812.8 kJ -----------------> 1
2Ca(s)+O2(g)-------------------> 2CaO(s), H= -1269.8 kJ ------------------------> 2
do the reverse of second eqation and divide with 2 and add to 1st eqaution
CaO (s) ------------------> Ca(s) + 1/2 O2 (g) , H= 634.9 kJ ------------------------> 3
add (1) + (3)
Ca(s) + CO2(g) + 1/2 O2(g)------------------>CaCO3(s), H= -812.8 kJ -----------------> 1
CaO (s) ------------------> Ca(s) + 1/2 O2 (g) , H= 634.9 kJ ------------------------> 3
----------------------------------------------------------------------------------------------------------------------------------------
CaO(s)+CO2(g)----------------------------> CaCO3(s) , H = -177.9 kJ
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.