Known Solutions
Known combinations of cations, or knowns, are created by grabbing a test tube from the test tube box and placing it in the holder. Cations are added by clicking the bottles on the stockroom shelves. Water can be added by clicking the water bottle. An actual picture of the contents of the test tube is shown in the Live Data tab display as cations are added. As in an actual laboratory, cations may not be removed from the test tube once added, but a test tube may be discarded by dragging it to the disposal bucket. Once a test tube has been prepared, it can be labeled and then used or taken to the test tube rack so another known solution can be created.
Practice Unknowns
The practice unknown screen is accessed by clicking on the “Create Unknown” button in the Unknowns tab. A practice unknown is created by selecting or defining a set of cations from which a certain number of cations will be randomly selected. The number of cations that will be selected from the defined set is also randomly determined as defined by the specified minimum and maximum limits. The minimum limit defines the minimum number of cations that can be selected from the set and the maximum defines the maximum number.
- Selecting the Cation Set. To define the set of cations, simply click the corresponding cation on the screen. A cation can be removed from the set by clicking the button again. Note that the number of cations in the set must be at least equal to the number specified in the Minimum setting.
- Setting Maximum. To set the maximum number of cations that can be included in the unknown, type the number in the Maximum box. You can also use the arrow keys to the right of the Maximum box. The up arrow adds 1 to the current number, and the down arrow subtracts 1. Note that Maximum cannot be set to less than 1. Note also that Maximum cannot be greater than the number of cations in the set. However, the number of cations in the set may exceed Maximum.
- Setting Minimum. To set the minimum number of cations that can be included in the unknown, type the number in the Minimum box. You can also use the arrow keys to the right of the Minimum box. The up arrow adds 1 to the current number, and the down arrow subtracts 1. Note that if Minimum is set to zero, then water (or no cations) can be assigned as a possible unknown. Note also that Minimum can be equal to but cannot exceed Maximum.
- Creating the Unknown. To exit the Practice Unknown screen and generate random practice unknowns, click on the Create button at the bottom of the window. The first practice unknown will be placed in the right slot of the unknown rack on the stockroom counter. New unknowns of the same set of cations can be generated by discarding the current practice unknown in the unknowns rack or by discarding all test tubes containing any part of the current practice unknown either in the holder or in the test tube rack on the lab bench.
- Cancel. To cancel making a practice unknown click on the "Clear” button.