TUGAS TERSTRUKTUR KIMIA DASAR
STIKES BANI SALEH PRODI FARMASI
TAHUN AJARAN 2020 – 2021
Semester
: I
Tugas Ke- : IX
Mata Kuliah : Kimia Dasar
1.
Use bond enthalpy to calculate the enthalpy of reaction:
H2 (g) + Cl2 (g)  2HCl (g)
2.
Use bond enthalpy to calculate the enthalpy of reaction:
H2 (g) + C2H4 (g)  C2H6 (g)
Bond
H-H
Cl-Cl
H-Cl
C-H
Bond Enthalpy (kJ/mol)
436,4
242,7
431,9
414
3. A gas expands in volume from 26,7 mL to 89,3 mL at constant temperature. Calculate the
work done (in joules) if the gas expands:
a. Against a vacuum
b. Against a constant pressure of 1,5 atm
c. Against a constant pressure of 2,8 atm
4. Calculate the work done in joules when 1,0 mole of water vaporizes at 1,0 atm and 100 0C.
Assume that the volume of liquid water is negligible compared with that of steam at 100
0
C, and ideal gas behavior.
5. Consider the reaction:
H2 (g) + Cl2 (g)  2HCl (g)
ΔH= -184,6 kJ/mol
If 3 moles of H2 react with 3 moles of Cl2 to form HCl, calculate the work done (in joules)
against a pressure of 1,0 atm at 25 0C. What is ΔE for this reaction? Assume the reaction
goes to completion.
6. A piece of silver of mass 362 g has a heat capacity of 85,7 J/0C. What is the specific heat
of silver?
7. Calculate the amount of heat liberated (in kJ) from 366 g of mercury when it cools from
77,0 0C to 12,0 0C!
8. The ΔHfo values of the two allotropes of oxygen, O2 and O3, are 0 and 142,2 kJ/mol,
respectively, at 25 0C. Which is the more stable form at this temperature?
9. Predict the value of ΔHfo (greate than, less than, or equal to zero) for these elements at 25
0
C:
a. Br2 (g) ; Br2 (l)
b. I2 (g) ; I2 (s)
Sari Defi Okzelia, M.Si.
Good Luck ;)
10.
The standard enthalpy change for the following reaction is 436,4 kJ/mol:
H2 (g)  H (g) + H (g)
Calculate the standard enthalpy of formation of atomic hydrogen (H)!
11.
Calculate the standard enthalpy change for the reaction:
2Al (s) + Fe2O3 (s)  2Fe (s) + Al2O3 (s)
Given that:
ΔHorxn = -1669,8 kJ/mol
2Al (s) + 3/2O2 (g)  Al2O3 (s)
2Fe (s) + 3/2O2 (g)  Fe2O3 (s)
ΔHorxn = -822,2 kJ/mol
12. Consider the following two reactions:
A  2B
ΔHorxn = ΔH1
AC
ΔHorxn = ΔH2
Determine the enthalpy change for the process:
2B  C
Sari Defi Okzelia, M.Si.
Good Luck ;)