## anonymous one year ago Which of the following compounds is saturated? A. C6H10 B. C7H14 C. C9H20 D. C9H14 Help! I am not sure how to do this problem...a step by step explanation would be wonderful. :)

1. anonymous

@dan815

2. Photon336

Saturated compound contains a double bond if this is the first time you're doing this you may want to draw out the compound first

3. Photon336

let's start with C6H10 Step #1 draw out the carbon backbone |dw:1441062004377:dw| Step #2 put in all the hydrogens and count them. Remember every carbon must have four bonds to it, ALWAYS.

4. Photon336

|dw:1441062178715:dw| NEXT we, put in all our hydrogens, we have used 10 hydrogens. BUT what do we need to finish this figure off?

5. Photon336

because the carbons are in a RING structure, each carbon is bonded to a carbon on the left and to the right so, it has 2 bonds already. you just need to put in the hydrogens 2 for each carbon in the ring.

6. anonymous

But the two on the left have only one hydrogen attached?

7. Photon336

@RobinJane Yes so we must put in a double bond, so that each carbon has four bonds so it would be like this. |dw:1441062556185:dw| So now you know what saturated is right vs un saturated? a compound must not contain any double bonds for it to be saturated. |dw:1441062449685:dw| any compound that has a double bond in it is unsaturated . |dw:1441062624115:dw|

8. Photon336

So to figure out this problem, you do the following; 1. on a piece of paper you count out the number of carbons in the formula. 2. then you place hydrogens on each carbon to make sure that the carbons have 4 bonds. 3. if you run out of hydrogens, then you would have to put in a double bond. 4. CARBON always Makes 4 bonds.

9. Photon336

One last thing saturated compounds will have the formula CnH2n+2 if I remember correctly. So you can see if a formula is unsaturated/vs saturated whether it will have a double bond. so for C7H14 You can test this out first; like you can put in 7 and see how many hydrogens that your compound must have to be saturated. if it has less than this you know it's unsaturated. so for C7H14; you know that n =7 right? well plug it into this formula C7 2(7) + 2 = 16 C7H16 but we have C7H14 ; SO This must be unsaturated

10. anonymous

SO it is not saturated?

11. Photon336

nope; but why?

12. anonymous

That makes sense... Aren't there two formulas?

13. anonymous

Is it better to plug into the formula, or to draw it?

14. anonymous

I mean, which method is better and more accurate?

15. Photon336

well I suggest drawing it out, because that way you get to see for yourself why it's saturated/vs un saturated. also if you take organic chem you may not be given a molecular formula like C7H2N etc... and they won't show you how it's drawn you'll have to draw it out yourself.

16. Photon336

like C9H20 can you draw that out for me?

17. anonymous

I am trying...just a moment...

18. anonymous

|dw:1441063493585:dw|

19. anonymous

Is this right?

20. anonymous

@Photon336

21. Photon336

You're almost there, so yeah you counted the carbons, put in the hydrogens, there's just one thing it's not a ring but it's straight chained.

22. anonymous

Oh!

23. anonymous

But the idea is similar, correct?

24. Photon336

yep. so make sure you count out all the hydrogens

25. anonymous

So that one is unsaturated?

26. anonymous

Let me try again...

27. Photon336

another question i have for you was does each carbon have 4 bonds?

28. Photon336

like whether it's a ringed structure vs straight chain that takes practice, wish I had a way to explain it but you will have to just keep seeing them

29. anonymous

|dw:1441064007882:dw|

30. anonymous

In this one, it is saturated!

31. anonymous

How do you do double bonds without adding more to carbon?

32. Photon336

excellent

33. anonymous

Is the top drawing correct?

34. Photon336

yes that's perfect, what did you mean about the double bonds?

35. anonymous

When it is unsaturated.

36. anonymous

Or do you just use the drawing to establish unsaturated vs saturated?

37. Photon336

Well in the figure you drew, that's unsaturated because there are no double bonds if it were saturated then you would have a double bond

38. Photon336

Hope this helps

39. anonymous

How do you draw it?

40. anonymous

Double bonds, that is?

41. Photon336

Just when you draw the bond between the carbon place another line on top of it should look like = an equal sign. Just remember that each of your carbons has four bonds. If your carbons have four bonds each of them then you can't have a double bond there b/c then those carbons will have 5 bonds no good