Questions involving log

[desi0chick]

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I was going through the BR General Chemistry Chapter, Acids and bases, and noticed many of the problems involved knowing the logarithmic values of log 8, log 9 etc. How do you guys approach these problems, just memorize the values given in the chapter?

 

[illinichief89]

you should know that log 8 < 1. Or log 9 < 1

Log 10 = 1
Log 1 = 0

Therefore, 0 < Log 9 < 1
You don't need to know exact values. One of the multiple choice answers will be between 0 and 1, and pick that answer. If there are two choices in that range then pick the choice that is closer to 1, since 9 is closer to 10 than it is to 1.

 

[Godric]

Or simply know log2=.3 and log3=.47~.4

so log8= log4x2=log2x2x2= .3+.3+.3= .9

and log9= log3x3=.47+.47=.94

TBR, showed the best way possible. If you can commit some of the other logs to memory it speeds up the process, but you can break almost everything down to 2s and 3s and work your way up.

 

[shaboobly]

i have never had to estimate a log because the logs you will encounter will prob deal with ph and concentration in which cause the 10 in the base in the log will become one and then you are just left with an exponent.

but idk. pre calculus was an easy class and i excelled in it. i am also a math minor.