In Chemistry, pH is the measure of the ion concentration in a liquid. It is used

Question

In Chemistry, pH is the measure of the ion concentration in a liquid. It is used as a measure of the acidity or basicity of the fluids and body tissues. It is a most important concept in medicine and other sciences. Pure water has a pH value of about 7. Anything with a pH value of less than 7 is considered an acid and anything with pH more than 7 is considered a base. As you may have guessed, pH is a log function: pH = - log H^+ where H^+ is the hydrogen ion concentration. (a) Rain water before the industrial revolution had a pH of 5. Acid rain, or rain in the United States, now has pH of about 4. Has the hydrogen concentration in rainwater increased or decreased since the industrial revolution and by how much? Note that you need to determine H^+ when pH is 5 and you need to determine H^+ when pH is 4 and then subtract to determine the amount of increase or decrease. (b) The "life range" of blood in a person must be between 7.1 and 7.7. That means people with blood outside this "life range" are dangerously ill. How much can hydrogen ions fluctuate so that a person's pH is in the "life range"?

Explanation / Answer

a) determining H+ when pH is 5

applying the formula

pH = - log H+

5 = - log H+

or H+ = 1 / e^5

= 0.0067

H+ when pH = 4

4 = - log H+

H+ = 1/e^4

H+ = 0.0183

hence,

amount of hydrogen concentration has incresed by 0.0183 - 0.0067 = 0.0116

b) when pH = 7.1

7.1 = - log H+

H+ = 1 / e^7.1

H+ = 0.000825

determining H+ when pH = 7.7

7.7 = -log H+

H+ = 1/e^7.7

H+ = 0.0004528

so, 0.000825 - 0.0004528 = 0.0003722

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