how does 1.2 x 10^-3 = 2.92???

Question

anonymous · Answer

attachment

aaronq · Answer

that's not right, but this is  $\sf \large -\color{red}{log}(1.2 *10^{-3}) = 2.92$

aaronq · Answer

take the logarithm (base 10) of that number

anonymous · Answer

@aaronq could you be more explanatory ?

aaronq · Answer

Use a calculator type in the number, press "log" then multiply by -1

aaronq · Answer

there's really not much else to it

anonymous · Answer

oh yea sorry

anonymous · Answer

does the iPhone have that button?

anonymous · Answer

@aaronq does the iPhone have that

aaronq · Answer

anonymous · Answer

how to i put 10 ^-3 in there

aaronq · Answer

you could write it in decimal form, 0.0012

anonymous · Answer

oh true

anonymous · Answer

@arronq thats -1.9208

aaronq · Answer

nope, it's -2.92, then you multiply by -1

aaronq · Answer

you wrote 0.012 not 0.0012

anonymous · Answer

how'd you get that

anonymous · Answer

no i wrote 0.0012

aaronq · Answer

try it again

anonymous · Answer

oh got it

anonymous · Answer

so for equations like this i just have to find the log base for that number and thats the answer? @aaronq

anonymous · Answer

and why do i get -2.92 instead of positive

aaronq · Answer

because you have to multiply by -1 as the formula states

$\sf \huge pH=\color{red}-log[H^+]$

aaronq · Answer

and yes, thats how you find the answer in these problems

anonymous · Answer

ok thanks

aaronq · Answer

np

anonymous · Answer

@aaronq what about this?

aaronq · Answer

it's the same thing

aaronq · Answer

write the number, press "log", then multiply by -1

anonymous · Answer

but 10^-13 is 1 . 10^3

anonymous · Answer

how do i put that in ??

aaronq · Answer

idk, it depends on your calculator, you might need brackets

1.0*10^(-13)

anonymous · Answer

hmm ill try one sec

anonymous · Answer

hey idk if i did it right but i got .0000000000001 @aaronq

anonymous · Answer

and for pH = -log [6.8 × 10-4]

pH = 3.17 i got 27.2

aaronq · Answer

you're probably not inputing the numbers correctly into the calculator you're using

anonymous · Answer

but 10^-4 in decimal is 0.0001 after pressing log its -4

anonymous · Answer

and then that positive 4

anonymous · Answer

6.8 * 4 = 27.2 @aaronq

aaronq · Answer

yeah, but that's not how scientific notation works

$6.8 * 10^{-4}=0.00068$