A chemistry problem

Question

The heating curve of substance X is shown below. The molar mass of substance X is 48.5 g/mol.

Use the following data to calculate the total heat needed to increase the temperature of 20.0 g of this       substance from 100.0°C to 130.0°C.    

cliquid = 1.25 J/g°C ∆Hvap = 3.89 kJ/mol cgas = 0.855 J/g°C

Answer 1

T_initial=100

T_final=130

From the graph, boiling point=120

liquid warms from 100 to 120 (q₁)

q₁=20(1.25)(120-100)

q₁=500 J

liquid boils (q₂)

The molar mass of substance X is 48.5 g/mol.

∆H_vap = 3.89 kJ/mol

20.0g/48.5=0.4124mol

q₂=0.4124mol(3.89kJ)

q₂=1.604kJ

q₂=1604 J

gas warms from 120 to 130 (q₃)

q₃=20(0.855)(130-120)

q₃=171J

q_total=q₁+q₂+q₃

=500+1604+171

q_total=2275 J