please help with chemistry i really need help this is hard?

  • Thread starter Thread starter little dragon
  • Start date Start date
L

little dragon

Guest
You have a series of four chemical reactions (1 2 3 4). How do you calculate the H3 if you know the others?

H3 = (H1)(H2)(H4)

H3 = H1 + H2 + H4

H3 = H1 + H2 H4

H3 = H4 (H1 + H2)



2. What is the value of the missing H in the following equations?
2S (s) + 3O2 (g) 2SO3 (g), H = 792 kJ
2S (s) + 2O2 (g) 2SO2 (g), H = ?
2SO2 (g) + O2 (g) 2SO3 (g), H = 198 kJ

594 kJ

198 kJ

+594 kJ

+792 kJ



3. By using the following reactions, calculate the heat of formation of pentane (C5H12) gas from carbon and hydrogen gas.
C (s) + O2 (g) CO2 (g), H = 395 kJ/mol
H2 (g) + 1/2O2 (g) H2O (l), H = 285 kJ/mol
C5H12 (g) + 8O2 5CO2 (g) + 6H2O (l), H = 3.54 × 103 kJ/mol


395 kJ/mol

285 kJ/mol

145 kJ/mol

77.0 kJ/mol



4. Hess's law is based on what principle?

conservation of mass

conservation of entropy

conservation of neutrality

conservation of energy



5. Given the following reactions, what is the H for this reaction?
NO (g) + O (g) NO2 (g)

NO (g) + O3 (g) NO2 (g) + O2 (g), H = 199 kJ
O3 (g) 3/2O2 (g), H = 142 kJ
O2 (g) 2O (g), H = +495 kJ

304 kJ

199 kJ

+154 kJ

+438 kJ
 
Back
Top