Question

In a solution at 25°C, the [H+] is 3.5 × 10−6 M. What is the [OH−]?

Answer 1

3.5 × 10−20 M

2.9 × 10−9 M

1.0 × 10−7 M

3.5 × 10−6 M

Answer 2

at 25 degrees celsius, \([H^+]*[OH^-]=1.0*10^{-14}\)

Answer 3

just rearrange that to solve for \([OH^-]\)

Answer 4

How do I rearrange it?

Answer 5

it's algebra, a*b=c,

if we solve for b, we have divide both sides by a, \(\dfrac{a*b}{a}=\dfrac{c}{a}\)

a's cancel on the left, \(\dfrac{\cancel a*b}{\cancel a}=\dfrac{c}{a}\)

we're left with: \(\dfrac{b}{a}=\dfrac{c}{a}\)

Answer 6

sorry i made a copy and paste error, were left with \(\large b=\dfrac{c}{a}\)

Answer 7

so for your equation, \( [H^+]∗[OH^−]=1.0∗10^{−14}\)


divide both sides by \([H^+]\): \( \dfrac{[H^+]∗[OH−]}{[H^+]}=\dfrac{1.0∗10^{−14}}{[H^+]}\)

\( \dfrac{\cancel {[H+]}∗[OH^−]}{\cancel {[H^+]}}=\dfrac{1.0∗10^{−14}}{[H^+]}\)


\( [OH^−]=\dfrac{1.0∗10^{−14}}{[H^+]}\)

Answer 8

if you see all these squares with question marks, refresh the page

Answer 9

Would I plug 3.5 × 10−6 M for H+?

Answer 10

yep !

Answer 11

Okay so bear with me

[H+] x [OH-] = 1.0 x 10^-14
[ 3.5 × 10^−6] x [?] = 1.0 x 10^-14

[ 3.5 × 10^−6]: [ 3.5 × 10^−6] x [?] 1.0 x 10^-14
------------------- = ------------
[ 3.5 × 10^−6] [ 3.5 × 10^−6]

[OH-] = 28571428.5

I don't understand

Answer 12

so you got this at the end, right?

1.0 x 10^-14
[OH^-] = --------------
[ 3.5 × 10^−6]

Answer 13

Yeah?

Answer 14

okay, that's good. I think you messed up in writing the numbers in your calculator, because the answer is the same.

you wrote \(\huge [OH^-]=\dfrac{1.0 *10^{14}}{ 3.5 *10^{−6}}\)


when it should've been \(\huge [OH^-]=\dfrac{1.0 *10^{\color{red}{-14}}}{ 3.5 *10^{−6}}\)

Answer 15

the answer is \(\large 2.857*10^{-9}\) but you got \(\large 2.857*10^{9}\)

Answer 16

or something like that

Answer 17

Thanks! I was really lost

Answer 18

no problem ! glad i could help ya out