Calculate the hydrogen ion concentration in the following biological fluids whose pH are given below:

Solution:

(a) Human muscle fluid 6.83:

$\mathrm{pH}=6.83$

$\mathrm{pH}=-\log \left[\mathrm{H}^{+}\right]$

$\therefore 6.83=-\log \left[\mathrm{H}^{+}\right]$

$\left[\mathrm{H}^{+}\right]=1.48 \times 10^{-7} \mathrm{M}$

(b) Human stomach fluid, 1.2:

$\mathrm{pH}=1.2$

$1.2=-\log \left[\mathrm{H}^{+}\right]$

$\therefore\left[\mathrm{H}^{+}\right]=0.063$

(c) Human blood, 7.38:

$\mathrm{pH}=7.38=-\log \left[\mathrm{H}^{+}\right]$

$\therefore\left[\mathrm{H}^{+}\right]=4.17 \times 10^{-8} \mathrm{M}$

(d) Human saliva, 6.4:

$\mathrm{pH}=6.4$

$6.4=-\log \left[\mathrm{H}^{+}\right]$

$\left[\mathrm{H}^{+}\right]=3.98 \times 10^{-7}$