Copy of Enthalpy and Internal Energy Prac 1 (5/28/2026)

Last updated about 2 hours ago

6 questions

Copy of Enthalpy and Internal Energy Prac 1 (5/28/2026)

Last updated about 2 hours ago

6 questions

Use information from the Thermochemistry Parts 1 and 2 notes, as well as any calculation examples that I have provided, to assist you with answering these questions.

Identify which of the following reactions are exothermic and which are endothermic:

a. 2 Mg(s) + O2(g) → 2 MgO(s)   ΔH = –1204 kJ _______ 
b. CaCl2 · 6 H2O(s) →(H2O)→ CaCl2(aq)  ΔH = 18.0 kJ _______ 
c. 4 NH3(g) + 3 O2(g) → N2(g) + 6 H2O(g)   ΔH = –1250 kJ _______ 
d. CH4(g) → C(s) + 2 H2(g)   ΔH = 412.0 kJ _______ 

Define internal energy. In your definition describe its relationship to work and heat.

For a certain process, the values for both q and w are negative. What do these values mean in terms of heat transfer and work done? In your answer, be sure to explain what happens to internal energy.

In a process, the internal energy of a system decreased to 10.4 kJ. The system absorbs 62.5 kJ of energy from its surroundings. Calculate how much work (w) the system did. Do not forget to include the units in your reported answer.

w = _______ 

Potassium bromide, KBr, has an enthalpy of formation of -393.8 kJ. Explain what this statement means.

Table - Enthalpies of Formation (link to the table, above)- https://docs.google.com/document/d/1eMtEzoL4hy-TEIY3um630ByOmg0HuXvanCew26Tp39Y/edit?usp=sharing