Define and provide an example of an exothermic chemical reaction:

Question

Define and provide an example of an endothermic chemical reaction:

Of the bonds listed below the weakest bond is _______ and the strongest is ________.
A strong bond is a (stable / unstable) bond

2(H—C ≡ C—H) + 5(O = O) → 4 (O=C=O) + 2 (H—O—H)

839 kJ/mol C ≡ C # of bonds ______ (product / reactant) side Energy:_____
495 kJ/mo O = O # of bonds ______ (product / reactant) side Energy:_____
413 kJ/mo C—H # of bonds ______ (product / reactant) side Energy:_____
745 kJ/mo C=O # of bonds ______ (product / reactant) side Energy:_____
467 kJ/mo H—O # of bonds ______ (product / reactant) side Energy:_____

Add the energies on the reactant side __________ kJ/mol
Add the energies on the product side __________ kJ/mol

This reaction is (exothermic / endothermic)
The reaction (produces / absorbs) __________ kJ when ____ moles of acetylene (C2H2) reacts.

Answer 1

An exothermic chemical reaction is a reaction that releases heat to its surroundings. One example of an exothermic reaction is the combustion of methane gas (CH4):

CH4 + 2O2 -> CO2 + 2H2O + Energy

In this reaction, methane (CH4) reacts with oxygen (O2) to form carbon dioxide (CO2) and water (H2O), while releasing energy in the form of heat.

An endothermic chemical reaction is a reaction that absorbs heat from its surroundings. One example of an endothermic reaction is the reaction between ammonium nitrate (NH4NO3) and water (H2O):

NH4NO3 + H2O -> NH4+ + NO3- + H2O + Energy

In this reaction, ammonium nitrate reacts with water to form ammonium ion (NH4+), nitrate ion (NO3-), and additional water, while absorbing energy in the form of heat.

Of the bonds listed below the weakest bond is C—H and the strongest is C ≡ C.

A strong bond is a stable bond.

2(H—C ≡ C—H) + 5(O = O) → 4 (O=C=O) + 2 (H—O—H)

C ≡ C: # of bonds = 1, on the reactant side
O = O: # of bonds = 5, on the reactant side
C—H: # of bonds = 4, on the reactant side
C=O: # of bonds = 8, on the product side
H—O: # of bonds = 4, on the product side

Add the energies on the reactant side: 4(413 kJ/mol) + 2(839 kJ/mol) = 4156 kJ/mol
Add the energies on the product side: 4(745 kJ/mol) + 2(467 kJ/mol) = 4428 kJ/mol

This reaction is endothermic.
The reaction absorbs 4428 kJ when 2 moles of acetylene (C2H2) reacts.