## KemiStry with Kayla and Sarah - Quiz 2 Review!

$\frac{d[R]}{dt}=-k[R]; \ln [R]=-kt + \ln [R]_{0}; t_{\frac{1}{2}}=\frac{0.693}{k}$

Kayla Denton 1A
Posts: 106
Joined: Fri Sep 26, 2014 2:02 pm

### KemiStry with Kayla and Sarah - Quiz 2 Review!

Here's a review video Sarah and I made for the upcoming quiz. Feel free to comment below with any questions. Good luck everyone!

(For those of you who can't view the video, here is a screen shot to summarize.)
Attachments

kemistry7.mov [ 340.87 MiB | Viewed 2321 times ]

Chem_Mod
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### Re: KemiStry with Kayla and Sarah - Quiz 2 Review!

Excellent video! I did a review just like this in my office hours. Your video will surely help numerous students for the quiz this week! Great job!

RaquelAvalos1K
Posts: 35
Joined: Fri Sep 26, 2014 2:02 pm

### Re: KemiStry with Kayla and Sarah - Quiz 2 Review!

Hey Kayla & Sarah!

Can you explain again why in the second order we derive [A]-2 to be -[A]-1 instead of -2[A]-3?
I'm not sure how negatives work with these derivatives.

Also, just for clarification, are each of the final equations are set up to find a new concentration since in each eaquation we separated [A] to one side of the equation?

Thank you!!

Best,

Raquel

Neil DSilva 1L
Posts: 70
Joined: Fri Sep 26, 2014 2:02 pm

### Re: KemiStry with Kayla and Sarah - Quiz 2 Review!

To go from [A]-2 to -[A]-1, you have to integrate it, not derive it.

But you're right, if we were to derive [A]-2, we would get -2[A]-3.

RaquelAvalos1K
Posts: 35
Joined: Fri Sep 26, 2014 2:02 pm

### Re: KemiStry with Kayla and Sarah - Quiz 2 Review!

Hey Neil!

Thank you!

So is the integration rule adding one to the exponent then putting that exponent in front?

Neil DSilva 1L
Posts: 70
Joined: Fri Sep 26, 2014 2:02 pm

### Re: KemiStry with Kayla and Sarah - Quiz 2 Review!

Integration is just reversing the process of finding the derivative, so you would add one to the exponent and divide by the new exponent (whereas in deriving something, you multiple by the exponent and then subtract one from the exponent).

RaquelAvalos1K
Posts: 35
Joined: Fri Sep 26, 2014 2:02 pm

### Re: KemiStry with Kayla and Sarah - Quiz 2 Review!

Awesome!

Thank you, Neil!!