Question

1) A 0.1375-g sample of solid magnesium is burned in a constant-volume bomb calorimeter that has a heat capacity of 3024 J/C. The temperature increases by 1.126 degrees C. Calculate the heat given off by the burning Mg, in kJ/g and kJ/mol.

2) Determine the amount of heat in kJ given off when 1.26 x 10^4 g of NO2 are produced according to the equation:

2NO (g) + O2 (g) --> 2NO2 (g)

and delta (H) = -114.6 kJ/mol

Answer 1

Don't hog the space. Post 1 question at a time. Show your work and/or explain what you don't understand about the problem. And don't change screen names;i.e., Vince and Tim.

Answer 2

1.
q = Ccal*(Tfinal-Tinitial) for the rxn.
q/0.1375 = q/gram
q/gram x atomic mass mg = q/mol. Change those to kJ/g and kJ/mol

Answer 3

2.
If 114.6 kJ are produced per 1 mol NO then 2*114.6 or 229.2 kJ will be produced for 2 mols(2*30 = 60 g).
You may want to check this out in the problem because it always leaves one in doubt exactly what is meant. I'll assume the above is correct.
Then 229.2 kJ x (1.16E4g/60) = heat produced.

Answer 4

A 6.22-kg piece of copper metal is heated from 20.5°C to 324.3°C. Calculate the heat absorbed (in kJ) by the metal. sCu= 0.385 J/ g oC

Answer 5

A 0.1375-g sample of solid magnesium is burned in a constant-volume bomb calorimeter that has a heat capacity of 3024 J/°C. The temperature increases by 1.126°C. Calculate the heat given off by the burning Mg, in kJ/g and in kJ/mol. s Mg = 1.020 J/ g oC