Clicking on the balance while in the main laboratory zooms into the balance view where solid reagents, organic liquids, and solutions can be weighed on the analytical balance. The primary use of the balance in the virtual laboratory is to weigh out solid reagents, organic liquids, metals, water, and ice for the various calorimetric experiments that can be performed in the laboratory. The essential features of the balance view are described below.
- Balance. The simulated balance is modeled after a typical analytical balance with a mass resolution of 0.2 mg. Items (beakers, weighing paper, and solids) can be weighed by dragging and dropping the item on the balance. The balance has a maximum capacity of 200 g. The Tare button can be used to tare or zero out the balance.
- Weigh Paper. A piece of weighing paper can be dragged from the stack of papers to either the balance or to the lab bench. Solid can be transferred from the reagent bottle to the weighing paper in the balance for weighing or onto the weighing paper on the bench top. Any solid on a weighing paper can be dragged and dropped into the beaker.
- Beaker. An empty beaker or one with a solution or water can be placed in the balance area for weighing. The balance area is the only location in the simulated laboratory where solid can be taken from a reagent bottle and then transferred either to a weighing paper or to a beaker. Note that solid can also be transferred directly to the beaker while the beaker is on the balance.
Bomb Cup. The bomb cup can also be placed in the balance area for weighing and for the loading of organic solid and liquid samples. The bomb cup will be located in the same position as the beaker shown in the Figure above.- Metals. Metal samples can also be placed in the balance area for weighing. The metal sample will be in a glass dish in the same location as the beaker or bomb cup. The metal sample can be weighed by dragging the sample to the balance with or without a piece of weighing paper present on the balance. It is recommended that the weighing of metal samples be done before the sample is heated since the metal sample will cool while the sample is in air.
- Scoop. The scoop is used to transfer solid from the reagent bottle to either a weighing paper, beaker, or bomb cup. The scoop is used by clicking on the scoop and dragging it to the mouth of the reagent bottle (with the lid off), and then hold the scoop down above the bottle where it will cycle through one of the five scoop sizes shown on the bottle label. After solid is on the scoop, it can then be dropped on a weighing paper, beaker, or the bomb cup. An alternate and perhaps easier method for loading the scoop is to click and hold on one of the scoop levels on the side of the bottle, which will then automatically load the scoop with the indicated amount of solid.
Pipet. The pipet is used to transfer liquid organic reagents from the reagent bottle to the bomb cup. The pipet is located in the same location as the scoop and replaces the scoop when a liquid organic reagent bottle is placed in the balance area. The pipet is used by clicking on the pipet and dragging it to the mouth of the liquid reagent bottle (with the lid off), and then pulling the pipet down the bottle label to one of the five volumes shown on the label. Like the scoop, the pipet can also be loaded by clicking and holding on one of the volume levels on the side of the bottle. The maximum volume that can be delivered is 1 mL. After the liquid is in the pipet, it can then be dropped on the bomb cup to deliver the liquid.- Reagent Bottles. Solid and liquid reagents must be placed in the balance area before the reagent can be transferred to a beaker, weigh paper, or the bomb cup. The balance area is the only location where solids and liquids can be transferred from the reagent bottles. When a bottle is placed in the balance area, the bottle lid is still on but can be removed by clicking on the lid. The lid can be replaced by clicking on the mouth of the jar. The bottle label, while in the balance area, shows scoops or liquid volumes with five different levels. These are used to determine the amount of reagent to place on the scoop or pipet.
- Disposal Bucket. The disposal bucket is used to dispose of weighing paper, the beaker, or to dispose of the contents of the bomb cup. Note that if the beaker is dropped on the disposal bucket, the beaker and its contents will be discarded.
- X Button. Clicking on the X in the upper right corner of the window will return the user to the regular laboratory view.
Weighing Solids or Liquids. In the calorimetry simulation, solids and liquids are weighed using the following sequence: (1) Place the reagent bottle and a beaker or bomb cup in the balance area and then click on the balance to zoom in. (2) Place either the beaker, weighing paper, or bomb cup on the balance and then Tare the balance. (3) Click on the reagent bottle lid to open it. (4) Click and drag on the scoop (or pipet for liquids) and place it "in" the bottle and then, without letting go, drag the scoop or pipet down the bottle label to choose the amount of solid or liquid to place on the scoop or in the pipet. An alternate and perhaps easier method for loading the scoop (or pipet) is to click and hold on one of the scoop (or pipet) levels on the side of the bottle, which will then automatically load the scoop or pipet with the indicated amount of solid or liquid. (5) Now drag the scoop to the beaker, weighing paper, or bomb cup on the balance until it snaps in place and drop the scoop or pipet. (6) Repeat the scooping or pipeting step as necessary to measure out the necessary quantity of solid or liquid. (7) If a weighing paper was used to weigh out the solid, drag the weighing paper with solid to the beaker and drop it to transfer the solid. (8) Note that a beaker, weighing paper, bomb cup, or metal sample can be dragged from the balance while in the laboratory view.