Chemistry
18 Online
OpenStudy (anonymous):
how to solve for
p[oH]
p[H]
on a calculator
(i understand how it works but the numbers do not come out correctly)
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OpenStudy (mos1635):
it depence on the calc...
try:
log
value
=
OpenStudy (anonymous):
hmm i just have to plug in -
then log
it prints out -log (
OpenStudy (anonymous):
its a TI 30x :/
OpenStudy (mos1635):
lets try something..
type:
log
100
=
OpenStudy (mos1635):
what is it say?
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OpenStudy (anonymous):
2
OpenStudy (mos1635):
log
0.001
=
?
OpenStudy (anonymous):
-3
OpenStudy (mos1635):
ok
OpenStudy (mos1635):
-
log
0.001
=
?
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OpenStudy (anonymous):
3
OpenStudy (mos1635):
working good
so:
-
log
(value of [H] )
=
.....
OpenStudy (anonymous):
thats the part i do not understand
OH = 3.0 * 10 ^-9
example H = 3.3 * 10^-6
how did the book get OH ?
OpenStudy (anonymous):
vice versa also :/
OpenStudy (mos1635):
pOH + pH = pKw
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OpenStudy (mos1635):
[H+] *[OH-] = Kw
OpenStudy (mos1635):
Kw=?
OpenStudy (mos1635):
lets take it from the top...
what you know
what to find?
OpenStudy (mos1635):
that is the yheory
mumbers...???
OpenStudy (anonymous):
i only got
1.0 * 10^14 = 3.3 * 10^-6 [OH]
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OpenStudy (anonymous):
but how do i punch it in on a calc?
OpenStudy (mos1635):
1.0*10^-14 seems like Kw
so
Kw = [ H+] [ OH-] =>
[ H+]= Kw / [ OH-] =>
[ H+]= 1.0 * 10^-14 / 3.3 * 10^-6 =>
[ H+]= 0.3 * 10^-8 =>
[ H+]= 3 * 10^-9
so
pH=-log[ H+] =>
pH=-log 3 * 10^-9
pH=8.5
OpenStudy (mos1635):
punch:
1
exp
-
14
/
3.3
exp
-
6
=
log
=
+-
OpenStudy (mos1635):
is it working???