Chemical Forums
Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: Superboy92 on October 16, 2012, 02:06:18 AM
-
1. 15.3 g of sodium nitrate was dissolved in water in a calorimeter and the temperature fell from 25.00 to 21.56. If the heat capacity of the solution and the calorimeter is 1071 J/C, what is the enthalpy change when 2.00 mole of sodium nitrate dissolves in water?
2. Calculate the enthalpy of formation for acetic acid from the following data:
CH3COOH (l) + 2O2 (g) --> 2 CO2 (g) +2 H2O (l) -871 kJ
C (graphite) + O2 (g) --> CO2(g) -394 kJ
H2 (g) + 1/2 O2 (g) --> H2O (l) -286 kJ
Ok, so for problem one, I started with (1071)(21.56-25.00)(15.3g) = -x(4.184)(21.56-0)(18.016) and I'm not sure if I'm doing it right? solved for x I got 34.7 g and I'm not sure where/what to do from there.
Can someone please show me the right way to do it and show the steps so I can understand and learn on how to solves these 2 problems?
For problem 2, I don't know how to start it
*MOD Edit -- add useful title*
-
2. Calculate the enthalpy of formation for acetic acid from the following data:
CH3COOH (l) + 2O2 (g) --> 2 CO2 (g) +2 H2O (l) -871 kJ
C (graphite) + O2 (g) --> CO2(g) -394 kJ
H2 (g) + 1/2 O2 (g) --> H2O (l) -286 kJ
2 x R2 + 2 x R3 - R1
-
Ok, so for problem one, I started with (1071)(21.56-25.00)(15.3g) = -x(4.184)(21.56-0)(18.016) and I'm not sure if I'm doing it right? solved for x I got 34.7 g and I'm not sure where/what to do from there.
Show units in the eqn.
you've multiplied J/C * C * gm
J*gm is not a sensible unit.