To keep the balance clean and to keep chemicals from mixing with other chemicals. Also some chemicals can react with the metal of the balance pan and cause it to corrode or rust. Always use weighing paper or a small dish or beaker to weigh out chemicals.
Certain chemicals can corrode the balance pan. It's also difficult to transfer what you have weighed, with any accuracy, from the balance to its destination.
Chemicals must be placed on weighing paper to correctly mass the total amount. Also, this reduces loss of chemicals weighed.
Wet objects should never be placed on a balance pan because they might react with the material of the pan and cause it to become corroded.
- the balance pan must be kept clean
- some substances can react with the metal of the pan
- the pan must be kept at a constant weight
r u in chem lab on thursdays?
Because
Take a double pan balance. place bromine in the left pan. Add alcohol to the right pan until the two pans of the balance are at the same height. Voila...you have balanced bromine and alcohol
The left pan of the balance can be used for counter weights. Another use might be to put an identical dish or beaker. Since taring can be error prone it would be better to counter balance.
grams and to calculate use a pan balance
To weigh things using a balance. Lboratory weights are used for two-pan balances. (the zodiac sign Libra is shown holking one type of two-pan balance) The object to be weighed is placed on one pan, and weights are placed on the other pan until the scale is balanced. The weights add up to the weight of the contents of the other pan. Weights are also used to calibrate and/or check the accuracy of other weighing instruments
To avoid the contact between chemicals and the metal of the pan; to avoid the contamination of the pan; for an easy and total recovery of the weighed chemicals.
Because
It is used to compare the mass of two objects
Four reasons: 1) If you put chemicals on the balance pan, they will contaminate the pan. 2) A lot of balances have flat pans. If you don't put the product in something, it'll get into the mechanics of your balance and mess it up. 3) Some chemicals react violently with each other when mixed. If you measured a lot of different chemicals on your balance and some of them were to fall off the edge of the pan and mix in the mechanism, you could have an explosion. 4) It's just easier to work with powders if they're in something!
The objects to be weighed are placed on the center of a pan so they can be weighed accurately, without the pan tipping over.
A pan balance is made out of two pans, two chains depending on how long youwant them, a piece of metal depending on how long you want it to be and twopieces of wood to make the stand for the scale.
A balance scale in its simplest form has a bar with a pan hanging at either end, and a fulcrum in the middle. A more elaborate (and accurate) design, the triple beam balance, has three bars, with movable weights on them, and only one pan in which to place the object that is to be weighed.
A top-pan balance has the advantage of being very simple to use. The user simply places the object to be weighed on the top pan and reads the corresponding weight from the scale. A top-pan balance also has the advantage of being very accurate, as long as it is properly calibrated. A top-pan balance also has several disadvantages. First, it can only be used to weigh objects that can be placed on the top pan. Second, the top pan is often very small, which limits the size of the objects that can be weighed. Finally, top-pan balances are often less sensitive than other types of balances, which means that they are not well suited for weighing very small objects.
The top loading balance is used in laboratories, jewelry stores, etc.; the pan is not protected by a casing. The sensibility is up to 10 mg.
The weight is measured by means of one or more bars (levers) with sliding weights that are marked with the exact weight that balances the contents in the pan. So the principle is a simple lever with weights on on one side of the fulcrum that balance the weight of the unknown object in the pan.
Because - increased pressure on one side of the weigh pan could give rise to false readings.
remove all objects from the pan balance