In chemistry, pH () (potential of hydrogen) is a numeric scale used to specify the acidity or basicity of an aqueous solution. It is approximately the negative of the base 10 logarithm of the molar concentration, measured in units of moles per liter, of hydrogen ions. More precisely it is the negative of the logarithm to base 10 of the activity of the hydrogen ion. Solutions with a pH less than 7 are acidic and solutions with a pH greater than 7 are basic. Pure water is neutral, at pH 7 (25C), being neither an acid nor a base. Contrary to popular belief, the pH value can be less than 0 or greater than 14 for very strong acids and bases respectively.

pH measurements are important in agronomy, medicine, biology, chemistry, agriculture, forestry, food science, environmental science, oceanography, civil engineering, chemical engineering, nutrition, water treatment and water purification, as well as many other applications.

The pH scale is traceable to a set of standard solutions whose pH is established by international agreement. Primary pH standard values are determined using a concentration cell with transference, by measuring the potential difference between a hydrogen electrode and a standard electrode such as the silver chloride electrode. The pH of aqueous solutions can be measured with a glass electrode and a pH meter, or an indicator.

What are the answers to this following set of questions:

1. what does pH mean?
2. what kind of scale?
3. what does it specify?
4. what is it the negative of?
5. measured in what?
6. what are pH less than 7?
7. and more than 7?
8. what is water?
9. what degree?
10. Is it a water or a base?
11. Can pH be less than 10?
12. less than 0?
13. greater than 14?
14. What is used to measure the pH of aqueous solutions?
15. and what else?
1. potential of hydrogen
2. numeric
3. the acidity or basicity of an aqueous solution
4. the base 10 logarithm
5. moles per liter
6. acidic
7. basic
8. neutral, at pH 7
9. 25C
10. neither
11. Yes
12. Yes
13. Yes
14. pH meter
15. a glass electrode