Red cabbage juice is a good indicator of pH because it contains flavin, a pigment molecule that changes colors according to the concentration of hydrogen ions in a solution. The juice is prepared by soaking chopped red cabbage in boiling water for at least 10 minutes and then filtering the solution to eliminate any plant material.Know More
The prepared red cabbage juice is red, purple or blue, depending on the pH of the water used in its preparation. The addition of lemon juice, an acid, lowers the pH and causes the juice to become red. The addition of ammonia, a base, raises the pH and causes the juice to turn blue. The addition of stronger bases raises the pH higher and the solution becomes green or yellow, depending on the strength of the base.
Scientists use pH to measure the acidity of a material. A low pH indicates a high hydrogen ion concentration and a high pH indicates a low concentration. At a pH of 7, the concentration of hydrogen and hydroxyl ions are equal, resulting in a neutral solution. Students can soak filter paper in the juice solution, allow it to dry, and then cut it into strips to create a portable pH indicator that allows them to test pH outside the lab.Learn more about Acids & Bases
A weak acid is defined by its lower level of ionization with the surrounding solution than strong acids, meaning that it has a lower tendency to exchange protons. Examples of weak acids include ethanoic acid, carbonic acid, hydrogen fluoride and acetic acid.Full Answer >
A strong acid is one that is 100 percent ionized in a solution, and a weak acid is one that doesn't ionize fully when dissolved in water. Sulfuric acid is an example of a strong acid, and hydrogen fluoride is a weak acid.Full Answer >
In chemistry, a buffer is a substance that is able to resist changes in pH when it is a part of a solution. Buffers are added to solutions to resist acidic or basic compounds.Full Answer >
Strong acids and strong bases dissociate completely into ions when in solution. The presence of free ions to move under an electric current makes them strong electrolytes.Full Answer >