Environmental Chemistry

Chemistry Level 2

The $\ce{pH}$ of a substance is the concentration $[\ce{H}^+]$ , measured in moles of $\ce{H} ^+$ per liter of substance. It is given by the formula $\ce{pH} = \log_{10} \frac {1}{[\ce{H}^+]}$ .

Find the concentration in moles per liter of hydrogen ion in a liter of acid rain that has a $\ce{pH}$ of 4.5.

The answer is 0.00003162.

2 solutions

Chew-Seong Cheong
Jul 20, 2015

$pH = \log_{10} \dfrac{1}{[H^+]} = - \log_{10} {[H^+]} = 4.5$

$\Rightarrow [H^+] = 10^{-4.5} = \boxed{3.162\text{E}-5}$ mole

Moderator note:

Simple standard approach.

Well well i couldn't understand how to write 3.125E-5 .LOL

Shounak Ghosh - 5 years, 10 months ago

Yes, I didn't know it work too. I just cut and paste from my spreadsheet and it worked. Cedie Comomot , you should ask for answer such as "Find the amount of hydrogen in $\times 10^{-5} \text{ mol}$ in a liter of acid rain...". I thought the answer was in $g$ .

Chew-Seong Cheong - 5 years, 10 months ago

A Former Brilliant Member
Jan 8, 2016

The $\ce{pH}$ scale was invented in 1910 by Dr Soren Sorenson, Head of Laboratory at Carlsberg Beer Company. The "H" in $\ce{pH}$ stands for hydrogen and the meaning of the "p" in $\ce{pH}$ , although disputed, is generally considered to mean the power of hydrogen. This scale is used to measure the acidity or alkalinity of water or water soluble substances including, but definitely not limited to, soil or rainwater. The $\ce{pH}$ scale ranges from 1 to 14, where seven is a neutral point. Values below 7 indicate acidity with 1 being the most acidic. Values above 7 indicate alkalinity with14 being the most alkaline: $\ce{pH}=-\log_{10} \ce{[H^+]}$ ,

where $\ce{pH}$ is the $\ce{pH}$ number between 1 and 14 and $\ce{[H^+]}$ is the concentration of hydrogen ions.

Environmental Chemistry

The answer is 0.00003162.

2 solutions

Moderator note:

0 pending reports