logarithm in g chem!!!

[paras]

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hey freinds,

please help me how to simplify logarithm in g.chem on hand.
fro eg. -log3*10^-7

thanks....

 

[tvndental]

log (AB) = log A + logB

so -log3*10^-7 = -( log 10^-7 + log 3)
= -log 10^-7 - log 3
= 7 - log 3

So you choose the answer that is a little less than 7.

Log 10 = 1. Log 3 = less than 1 closer to the zero side.
So 7 minus a really small number close to 0

If its a number higher than 5 then it will be closer to the 1 side but less than 1. So if it like log 9 then the answer should be close to 6 but higher than 6.

 

[emmydpg]

Answer:
log10^-7<log 3*10^-7<log10^-6

-7<log 3*10^-7< -6

so the answer is going to be between -7 to -6.

Hopefully this helps.

 

[afzwin]

please help me how to simplify logarithm in g.chem on hand.
fro eg. -log3*10^-7.

If you have y*10^-x, first pretend y is 1 and then adjust for y's actual value. For example, -log of 1x10^-7 is 7... but 3x10^-7 is BIGGER (closer to 1x10^-6), so the -log is LESS THAN 7 (closer to 6). If y is 1.1, it's just a little bit less than 7... if it's 9, it's a LOT less than 7 (really close to 6). If it's 3, it's probably about .4 less than 7, so about 6.6. That method works for other exponents (e.g. 2x10^-12 = 12 minus a little, or 11.7... or 4x10^-4 = 4 minus a lot, or 3.4).

Good luck!

 

[paras]

i got it now... thanks alot.... i really appreciate to all of u for taking time for helping me.... !!! 🙂