MediumChemistryHigh School (9–10)GeneralCarbon and Its Compounds › Covalent Bonding and AllotropesNumericalBoard Exam
The numbers of different alkanes with 7, 8, 9 and 10 carbon atoms are 9, 18, 35 and 75…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
The numbers of different alkanes with , , and carbon atoms are , , and .
- How many times more alkanes are there with carbon atoms than with ?
- Does the number grow by the same amount at each step? What does it roughly do instead?
Need a reminder? The key ideaShow
Covalent compounds are made of molecules. The forces between the molecules are weak, so they melt and boil low, and they have no ions, so they do not conduct. Carbon forms millions of compounds because of catenation (chains, branches and rings) and tetravalency (four bonds).
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. (a) times as many.
Step 2. (b) Differences. , , . The steps are not equal.
Step 3. Ratios. , , . The number roughly doubles with each carbon atom.
Answer: (a) times; (b) no, it roughly doubles at each step.
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