q is computed in steps.
Within a phase q = mass x specific heat x (Tfinal-Tinitial). For example, to heat 20 g H2O from zero to 100 C (within the liquid phase) it requires
q = 20g x 4.184 J/g*C x (100C-0C) = ?
At a phase change (solid to liquid or liquid to vapor) it is q = mass x heat fusion to melt or mass x heat vaporization to change to vapor.
For example, q to change 20 g liuqid H2O to steam is
q = 20 x 2260 kJ/g = ?kJ.
Then added the qs together.
You have a solid phase from -30 to zero. It changes to a liquid at zero, is a liquid to 100, changes to a vapor at 100, is steam from there to 140 C.
For part 2.
work is p* delta V.
Calculate the volume at -30 and the volume at 140.
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Consider the process where 1.3 moles of ice, initially at -30.0 C, is heated to 140.0 C at constant pressure of 1.00 atm. The molar heat capacities (Cp) for solid, liquid, and gaseous water (37.5 J K-1 mol-1, 75.3 J K-1 mol-1, 36.4 J K-1 mol-1, respectively) are assumed to be temperature independant. The enthalpies of fusion and vaporization are 6.01 kj/mol and 40.7 kj/mol, respectively. Assume ideal gas behavior.
Calculate the heat, q
calculate the work
1 answer
1 answer