# Pre Calculs

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The pH of a chemical solution is given by the formula pH = -log10 [H+] where [H+] is the concentration of hydrogen ions in moles per liter. Values of pH range from 0 (acidic) to 14 (alkaline).
(a) what is the pH of the solution for which [H+] is 0.1?
(b) What happens to pH as the hydrogen ion concentration decreases?
(c)Determine the hydrogen ion concentration of an orange pH =3.8
(d) Determine the hydrogen ion concentration of human blood pH =7.4

All of these are simple log questions.

Are you having trouble with logs? For example, the answer to part (a) is just the -log(0.1).

I am. These are all log questions. And I think the main problem is how to put the question into my calculator. I am struggling the logs . Our teacher doesn't seem to teach things to our level.

For (a) use H+ = .01 in the formula to get
pH=-log10[.1] = -log10[10^-1]
For (b) you should see that the - sign before the log tells us the pH and H+ are inversely related.
For (c) set pH=3.8 in the formula and solve for H+
3.8=-log10[H+]
and for (d) 7.4=-log10[H+], so solve for H+.