Quiz & Worksheet - Bond Energy | Study.com - Free Printable

Let’s go through each question one by one, step by step.

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Question 1: Which chemical bond has the highest bond energy?

We’re given different bond lengths:
- 120 pm
- 150 pm
- 100 pm
- 115 pm
- “All same” — we can ignore this because bond length and bond energy are related.

Here’s the key idea: Shorter bonds are stronger. That means they have higher bond energy. Why? Because when atoms are closer together (shorter bond), they’re held more tightly — it takes more energy to break them apart.

So let’s compare the numbers:
- 100 pm is the shortest → strongest bond → highest bond energy
- Then 115 pm
- Then 120 pm
- Then 150 pm (longest → weakest)

✔ So the answer is: Bond length of 100 pm

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Question 2: An exothermic reaction

Let’s remember what “exothermic” means:
- “Exo” = out
- “Thermic” = heat/energy

So an exothermic reaction releases energy to the surroundings.

That also means:
- The products have less energy than the reactants (because some energy was released).
- It feels hot or warm if you touch the container.

Now look at the options:

A. absorbs energy → that’s endothermic ✘
B. gives out energy → YES ✔
C. energy of products < reactants → YES ✔
D. energy of reactants < products → no, that’s endothermic ✘
E. Both B and C → YES! That’s correct ✔

✔ So the best answer is: Both gives out energy to the environment and the energy of the products is lower than reactants

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Question 3: Using the table of Average Bond Energies in the lesson, which bond is the strongest?

Even though we don’t see the actual table here, we can use general chemistry knowledge about bond strengths.

Strongest bonds are usually:
- Triple bonds > double bonds > single bonds
- Bonds between small atoms (like O=O or H-Cl) tend to be strong too.

Let’s list the options:
- C-C → single bond → weak
- O-O → single bond → even weaker (oxygen doesn’t like bonding with itself much)
- C=C → double bond → stronger than single
- O=O → double bond → quite strong
- H-Cl → single bond but very polar → actually pretty strong for a single bond

But wait — among these, O=O (double bond between two oxygen atoms) is known to have high bond energy (~498 kJ/mol).
H-Cl is also strong (~431 kJ/mol), but less than O=O.
C=C is ~614 kJ/mol — wait, that’s higher!

Hold on — let me double-check standard average bond energies (from memory):

- C-C: ~347 kJ/mol
- O-O: ~146 kJ/mol (very weak!)
- C=C: ~614 kJ/mol
- O=O: ~498 kJ/mol
- H-Cl: ~431 kJ/mol

So actually, C=C has the highest bond energy among these!

Wait — but sometimes people think O=O is stronger… but no, carbon-carbon double bond is stronger than oxygen-oxygen double bond.

✔ So the strongest bond here is: C=C

*(Note: If your lesson’s table says something different, always go with what’s in your table — but based on standard values, C=C wins.)*

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Final Answer:
1. Bond length of 100 pm
2. Both gives out energy to the environment and the energy of the products is lower than reactants
3. C=C