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Modules Open College - e-Learning Content Library
Acid-Base Reactions
This model illustrates some of the properties of acids and bases, as well as the properties of salts that are produced as a result of acid-base reactions. In the model's main window, the flasks with acids are located in the upper row, while the flasks with bases are located in the lower row. In order to determine the acidity of a solution, litmus is added to the flasks that contain the solutions and to the large flask where the reactions take place. Combine one substance from the upper row and one substance from the lower row in the flask, and observe which color the indicator will turn. To do that, drag the appropriate test tube towards the flask, and drop it when it supersedes the flask. Before you start any further testing, make sure to empty the flask by dragging it to the waste tank.

There are two possible feedback signals that you can receive from the model. A green checkmark indicates that the procedure is permissible while a red cross indicates that the procedure is prohibited. A device for measuring the electric conductivity of the solution can also be inserted into the large flask (as well as into the individual reagent flasks). The device is located at the right lower side of the model's main window. Conductivity value is characterized by the pointer deviation from its vertical position. At the bottom of the model, the name of the substance that has been poured into the flask is indicated. If an acid and a base are mixed in the flask, the ensuing reaction's equation will be displayed. Note that strong acids (such as HCl, H2SO4 and HNO3) and strong bases (such as NaOH solution in our model) have higher conductivity, i.e. they are strong electrolytes. All highly soluble salts (like the ones that are presented in this model) are strong electrolytes too, - in spite of the fact that they have been obtained as a result of reactions between weak acids and weak bases.

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