Isomers - Worksheet #6 | Exams Chemistry | Docsity - Free Printable
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Step-by-step solution for: Isomers - Worksheet #6 | Exams Chemistry | Docsity
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Show Answer Key & Explanations
Step-by-step solution for: Isomers - Worksheet #6 | Exams Chemistry | Docsity
Let’s solve both problems step by step, with clear explanations.
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## Problem 1: Which of these pairs are structural isomers?
Structural isomers are compounds that have the same molecular formula but different connectivity (i.e., atoms are bonded in a different order or arrangement).
We’ll analyze each pair:
---
Left structure:
Cl–CH₂–CH₂–Cl → 1,2-dichloroethane
Right structure:
Cl–CH₂–CH₂–Cl → same as left, just drawn flipped.
✔ Identical molecules — not isomers.
> *Note: Rotation or flipping doesn’t change identity. Both are 1,2-dichloroethane.*
---
Left:
H–C(Br)=C(Br)–H → cis-1,2-dibromoethene (both Br on same side)
Right:
H–C(Br)=C(H)–Br → trans-1,2-dibromoethene (Br on opposite sides)
These are geometric isomers (stereoisomers), not structural isomers.
✘ Not structural isomers — they differ in spatial arrangement, not connectivity.
---
Left:
CH₃–CHCl₂ → 1,1-dichloroethane
Right:
ClCH₂–CH₂Cl → 1,2-dichloroethane
Molecular formula for both: C₂H₄Cl₂ → same.
But connectivity differs:
- Left: both Cl on same carbon (carbon 1)
- Right: one Cl on each carbon
✔ Structural isomers!
---
Left:
Structure shows a 3-carbon chain with CH₃–CH₂–CH₃ → propane
Right:
Same structure, just rotated/drawn differently → still propane
✔ Identical molecules — not isomers.
---
Left:
CH₃–CH(OH)–CH₃ → 2-propanol (isopropanol)
Right:
CH₃–CH₂–CH₂–OH → 1-propanol
Molecular formula for both: C₃H₈O → same.
Connectivity differs:
- Left: OH on middle carbon
- Right: OH on terminal carbon
✔ Structural isomers!
---
c and e are structural isomers.
---
## Problem 2: Identify if pairs are identical, isomers, or different compounds
We compare molecular formulas and connectivity.
---
Left:
CH₃–CH₃ → ethane
Right:
H₃C–CH₃ → same as ethane, just written differently
✔ Identical
---
Left:
CH₃–CH₂–CH₃ → propane
Right:
CH₃–CH₂–CH₃ → same structure, just drawn at an angle
✔ Identical
---
Left:
CH₃–CH₂–OH → ethanol (C₂H₆O)
Right:
CH₃–CH₂–CH₂–OH → propanol (C₃H₈O)
Different molecular formulas → different compounds.
✘ Different compounds
---
Left:
CH₃–CH=CH₂ → propene (C₃H₆)
Right:
Cyclic structure: cyclopropane (C₃H₆)
Same molecular formula → isomers.
Connectivity differs:
- Propene: open chain with double bond
- Cyclopropane: ring with all single bonds
✔ Isomers
---
| Pair | Identical / Isomers / Different compounds |
|------|-------------------------------------------|
| a | Identical |
| b | Identical |
| c | Different compounds |
| d | Isomers |
---
## 📌 Summary:
- a: Identical
- b: Identical
- c: Different compounds
- d: Isomers
Let me know if you’d like visual diagrams or further clarification!
---
## Problem 1: Which of these pairs are structural isomers?
Structural isomers are compounds that have the same molecular formula but different connectivity (i.e., atoms are bonded in a different order or arrangement).
We’ll analyze each pair:
---
a.
Left structure:
Cl–CH₂–CH₂–Cl → 1,2-dichloroethane
Right structure:
Cl–CH₂–CH₂–Cl → same as left, just drawn flipped.
✔ Identical molecules — not isomers.
> *Note: Rotation or flipping doesn’t change identity. Both are 1,2-dichloroethane.*
---
b.
Left:
H–C(Br)=C(Br)–H → cis-1,2-dibromoethene (both Br on same side)
Right:
H–C(Br)=C(H)–Br → trans-1,2-dibromoethene (Br on opposite sides)
These are geometric isomers (stereoisomers), not structural isomers.
✘ Not structural isomers — they differ in spatial arrangement, not connectivity.
---
c.
Left:
CH₃–CHCl₂ → 1,1-dichloroethane
Right:
ClCH₂–CH₂Cl → 1,2-dichloroethane
Molecular formula for both: C₂H₄Cl₂ → same.
But connectivity differs:
- Left: both Cl on same carbon (carbon 1)
- Right: one Cl on each carbon
✔ Structural isomers!
---
d.
Left:
Structure shows a 3-carbon chain with CH₃–CH₂–CH₃ → propane
Right:
Same structure, just rotated/drawn differently → still propane
✔ Identical molecules — not isomers.
---
e.
Left:
CH₃–CH(OH)–CH₃ → 2-propanol (isopropanol)
Right:
CH₃–CH₂–CH₂–OH → 1-propanol
Molecular formula for both: C₃H₈O → same.
Connectivity differs:
- Left: OH on middle carbon
- Right: OH on terminal carbon
✔ Structural isomers!
---
✔ Final Answer for Problem 1:
c and e are structural isomers.
---
## Problem 2: Identify if pairs are identical, isomers, or different compounds
We compare molecular formulas and connectivity.
---
a.
Left:
CH₃–CH₃ → ethane
Right:
H₃C–CH₃ → same as ethane, just written differently
✔ Identical
---
b.
Left:
CH₃–CH₂–CH₃ → propane
Right:
CH₃–CH₂–CH₃ → same structure, just drawn at an angle
✔ Identical
---
c.
Left:
CH₃–CH₂–OH → ethanol (C₂H₆O)
Right:
CH₃–CH₂–CH₂–OH → propanol (C₃H₈O)
Different molecular formulas → different compounds.
✘ Different compounds
---
d.
Left:
CH₃–CH=CH₂ → propene (C₃H₆)
Right:
Cyclic structure: cyclopropane (C₃H₆)
Same molecular formula → isomers.
Connectivity differs:
- Propene: open chain with double bond
- Cyclopropane: ring with all single bonds
✔ Isomers
---
✔ Final Answer for Problem 2:
| Pair | Identical / Isomers / Different compounds |
|------|-------------------------------------------|
| a | Identical |
| b | Identical |
| c | Different compounds |
| d | Isomers |
---
## 📌 Summary:
Problem 1: Structural isomers → c and e
Problem 2:
- a: Identical
- b: Identical
- c: Different compounds
- d: Isomers
Let me know if you’d like visual diagrams or further clarification!
Parent Tip: Review the logic above to help your child master the concept of isomers worksheet.
