Of course! Let's solve this step by step.
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🧪 What is an Empirical Formula?
The
empirical formula of a compound shows the
simplest whole-number ratio of atoms of each element in the compound. It does *not* necessarily show the actual number of atoms (that’s the molecular formula), but the smallest ratio that represents the composition.
To find the empirical formula from a molecular formula, you need to:
1. Look at the subscripts (number of atoms) for each element.
2. Find the
greatest common divisor (GCD) of all the subscripts.
3. Divide each subscript by the GCD to get the simplest whole-number ratio.
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Let’s go through each compound:
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1. C₄H₈
- Subscripts: C = 4, H = 8
- GCD of 4 and 8 is
4
- Divide each by 4:
- C: 4 ÷ 4 =
1
- H: 8 ÷ 4 =
2
-
✔ Empirical formula:
CH₂
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2. C₃H₆
- Subscripts: C = 3, H = 6
- GCD of 3 and 6 is
3
- Divide each by 3:
- C: 3 ÷ 3 =
1
- H: 6 ÷ 3 =
2
-
✔ Empirical formula:
CH₂
*(Note: Both C₄H₈ and C₃H₆ have the same empirical formula — CH₂ — because they are both multiples of CH₂.)*
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3. C₅H₁₀O₅
- Subscripts: C = 5, H = 10, O = 5
- GCD of 5, 10, and 5 is
5
- Divide each by 5:
- C: 5 ÷ 5 =
1
- H: 10 ÷ 5 =
2
- O: 5 ÷ 5 =
1
-
✔ Empirical formula:
CH₂O
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4. P₃N₅
- Subscripts: P = 3, N = 5
- GCD of 3 and 5 is
1 (they are coprime)
- So, we can’t simplify further.
-
✔ Empirical formula:
P₃N₅
*(This is already the simplest whole-number ratio.)*
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5. C₅H₁₂
- Subscripts: C = 5, H = 12
- GCD of 5 and 12 is
1 (no common factor other than 1)
- So, no simplification possible.
-
✔ Empirical formula:
C₅H₁₂
*(This molecule cannot be reduced further — it’s already in its simplest ratio.)*
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##
✔ Final Answers:
| Molecular Formula | Empirical Formula |
|-------------------|-------------------|
| C₄H₈ |
CH₂ |
| C₃H₆ |
CH₂ |
| C₅H₁₀O₅ |
CH₂O |
| P₃N₅ |
P₃N₅ |
| C₅H₁₂ |
C₅H₁₂ |
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✔ You can now fill in the blanks on your worksheet with these answers!
Let me know if you want to understand why some compounds share the same empirical formula or how to go the other way (from empirical to molecular).
Parent Tip: Review the logic above to help your child master the concept of empirical formula worksheet answers.
