Think about whether the answer makes sense.Values slightly less than 0 and greater than 14 may occur, but you’ll never see a pH of -23 or 150, for example. In chemistry, using the wrong number of digits may be counted as an incorrect answer, even if you set up the problem correctly. Use the correct number of significant figures.So, you can use K w value to predict whether a solution is an acid or a base:Īvoid common pitfalls when calculating pH: K w is the dissociation constant of water. In a way, water acts as both an acid and a base because it dissociates to produce a hydrogen ion and a hydroxide ion: PH stands for “power of hydrogen” because the strength of an acid depends on the amount of hydrogen ion (H +) it releases in aqueous (water-based) solutions. You can rearrange the pH equation to find hydrogen ion concentration from pH:Ĭalculate from a known pH. Exampleįind the pH of a 0.03 M solution of hydrochloric acid, HCl.įor bases, weak acids, and weak bases, the calculation is slightly more involved. In other words, the hydrogen ion concentration is the same as the acid concentration. If you have a strong acid, this is easy because strong acids completely dissociate into their ions. Sometimes you aren’t given the hydrogen ion concentration, so you have to figure it out from the chemical reaction or concentration of the reactants or products. PH = – log (0.0001) = 4 Calculate the pH of a Strong Acid Or, you could just use a calculator to take the log. Here it helps to rewrite the concentration using scientific notation as 1.0 x 10 -4 M. Example 1įind the pH if the H + concentration is 0.0001 moles per liter. Ph chemistry calculator how to#Here are simple example problems showing how to calculate pH when given hydrogen ion concentration. While negative pH is possible, your answer will almost always be a positive number. The easiest way to perform the calculation on a scientific calculator is to enter the hydrogen ion concentrations, press the log key ( not the ln key, which is natural logarithm), and then take the negative of the value. To calculate pH, first convert concentration to molarity. In a chemistry problem, you may be given concentration in other units. Molarity is given in units of moles per liter of solution. It includes formulas for finding pH and examples showing how to use them. Here is a quick review of how to calculate pH. Values less than 7 are acidic, while those greater than 7 basic. In chemistry, pH is a number that acidity or basicity (alkalinity) of an aqueous solution. To calculate pH, take the log of the hydrogen ion concentration and change the sign of the answer. This entry was posted on Jby Anne Helmenstine (updated on August 13, 2022)
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |