Calculator? Need help

[hersheyslove]

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Hi!
Are we supposed to bring calculator during general chemistry? I am doing some of the pH calculate in destroyer. Without calculator, i cannot figure out what is the -log(2.23*10^-7).
Thanks

 

[Andrew324]

no calc, its not that hard, you will get the hang of it pretty quickly, do a quick search for log functions. Play with the calculator a bit.

 

[Jake8]

answer is about 6.8 or so. Basically you need to be able to just fire these things off the top of your head. After a couple of hundred it starts to make sense. Realize that most of the answers will be spread out upon the spectrum so if you answer is relatively close to one of their answer choices then it is most likely correct.

For that problem the answer choices would be something like

a)1.0
b)3.0
c)7.0
d)10.0

The only answer close would be C regardless of if you could solve it the the millionth decimal. Time is of the essence work smart and quick.

 

[Mamona]

Hi!
Are we supposed to bring calculator during general chemistry? I am doing some of the pH calculate in destroyer. Without calculator, i cannot figure out what is the -log(2.23*10^-7).
Thanks

Somewhere in destroyer they teach you how to deal with logs. But it is quite simple in your example the exponent-7 is the indication for you that the log is between 6-7 (always the exponent -1 is the range in which your answer is going to be). So far we know that the first part of the answer is 6.... Now the second part of the answer involve 2.23. I usually have like a scale from 1 - 9 and count backwards, hard to explain but stay with me... if the question is for instance -log(9*10-7; we know first part is 6. and if I explain my self right the answer in here would be close to 6.1. For your example would be close to 6.8.
I hope this help if you have any question let me know

 

[Neil45]

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[hersheyslove]

Wow! Thanks so much guys! 👍