A patient's urine sample gave a pH reading of 8.2. What is the value of #[H_3O^+]# in this?

1 Answer
Stefan V.
Nov 28, 2015

#6.31 * 10^(-9)"M"#

Explanation:

This is a pretty straightforward problem that can be solved by using the equation

#color(blue)(["H"_3"O"^(+)] = 10^(-"pH"))#

In your case, the concentration of hydronium ions, #"H"_3"O"^(+)#, will be equal to

#["H"_3"O"^(+)] = 10^(-8.2) = 6.31 * 10^(-9)"M"#

Interestingly enough, the normal pH range for urine lies between #4.8# and #8.0#, so your patient's urine sample could be an indicator of a metabolic problem.

By comparison, the normal pH range for blood is much less susceptible to variation. For a healthy individual, blood pH ranges from #7.35# to #7.45#.

This pH range is controlled by the carbonic acid/bicarbonate buffer, one of the body's main buffer systems.

https://fmss12uchemd.wordpress.com/2013/05/06/carbonic-acid-bicarbonate-buffer-system/

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