Posted: 3/15/2008 8:08:21 AM EDT
| Just curious. Do solids have a pH level, or does it only apply to liquids? |
No, pH refers to solutions. Here's a dumbed down explanation. PH refers to free H or OH molecules in solution. If you have a lot free H ions then it's acidic, <7. If you have a lot of free OH ions it's basic, >7. When you put a solid into liquid it will release it's H or OH ions to create the pH. If you put Sodium Hydroxide into water the Na and OH will dissociate. Sodium has a charge of +1 and Hyrdoxide has a charge of -1 so they are held together by an ionic bond which is weak in comparison to a covalent bond. So, the charges dissociate and are no longer ionicaly bonded. Now there will be an excess of OH ions so you will have created a basic solution. If you put 40 (NaOH's molecular weight is 40) grams on NaOH into water and bring the volume to 1L you will have made a 1 Molar solution. You can pH the solution and determine its basicity. If you then add more water you will have diluted out the OH ions so the pH will then drop down from where it was at. If you simply stick a pH probe into NaOH granules it won't give you anything meaningful. Soil pH is tested using water or the water existing within the soil. |