Question

The decomposition of an aldehyde solution in carbon tetrachloride is a first order reaction with a rate constant of 1.20 x 10-3 min-l. If we start with [aldehyde] = 0.0500 molar, what will the concentration be 150 minutes later?


a. 0.00900 M b. 0.0418 M c. 0.00926 M d. 0.00499M e. 0.000333 M

First time on this site, really need some chemistry help with answer

Answer 1

We're glad to have you, first time or not BUT don't change screen names. We can help you faster if we can keep up with the kind of questions you are asking. And we're faster at it too if you keep the same screen name.
Use ln(No/N) = kt
You're given k, substitute that and the other values and solve for N.

Answer 2

According to our book we are supposed to use the following

ln (N/No) = -kt

Are both equations correct?

Answer 3

Yes. If you place a negative sign, then the ln No/N term is reversed (take the reciprocal).