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Weighing bottle cap also made of glass with a transparent color. Between the weighing bottle body and the lid, there is a section called grinding parts. This section intentionally made rough, so airtight weighing bottle. When closed, no incoming air and no air coming out so that the solids contained in the weighing bottle are not contaminated from or to the outside.
How to use the weighing bottle for weighing is clean the weighing bottle before and after use with water and then with soap, and then brushed with a brush tube, and finally rinsed again with water. Then dried with a tissue. At the time of the process to weigh wear disposable rubber gloves or use a tissue to hold the weighing bottle. This is done because the fat that is on hand will add weight so weighed become inaccurate.
Constant weighing means a container that is weighted to have the same weight when weighed 2 times in a row. Constant weighing is usually performed to determine the levels of a substance called gravimetric method. For example, in the determination of water content in the flour can use weighing bottle is heated in an oven of 100°C so that the water evaporates. and the water content of the flour can be calculated.
How to use the weighing bottle for constant weighing is the weighing bottle weighed with an analytical balance in order to get the weight up to 4 digits behind the comma, for example 2.2345 gram. This is called the first weight. hold the weighing bottle with rubber gloves or tongs or tissue during this process. Then put in a preheated oven at 100°C which has been heat evenly for 1 hour. Then cool outside the oven for 15 minutes, then insert it into a desiccator containing silica gel to draw water.
Desiccator is a thick glass container, a diameter 10 cm at the bottom and a diameter of 15 cm at the top. In the midst of the inner basin desiccator there as a silica gel. Then given a porcelain with small holes. Desiccator has a cover and in the middle of the cover there is a big round button to hold the lid. Include desiccator bodies smeared with vaseline so that the lid body and the cover attached and airtight, but can still be opened by hand easily. How to open and close the slide is pushed desiccator lid horizontal. do not insert weighing bottle from the oven directly into the desiccator while still hot. Heat from the weighing bottle will cause the air to push the lid desiccator out if this impulse. If it is very strong it can cause desiccator lid floating or flying up.
After 30 minutes in the desiccator, download weighing bottle from the desiccator and weigh it again with analytical balance. So we get a second weight. Repeat the process of heating in the oven to be weighed with an analytical balance to obtain the third weight. If the weight of the second and third weight difference is not more than 1%, it has obtained a constant weight of weighing bottle. But if the difference is more than 1%, then repeat this process to obtain the weight of the fourth, fifth, and so on until a constant weight is obtained.
Then weigh the sample flour, for example 1.5676 grams in the constant weighing, this weight called flour weigh, then reheat in a preheated oven at 100°C for 2 hours. Then repeat the process as above until weighing the weighing bottle with analytical balance and weight of flour obtained first. Reheat the flour in the oven for 1 hour and repeat the process until the weight is obtained. If the first weight and the second weight difference is not more than 1%, it has obtained a constant flour weight. But if the difference is more than 1%, then repeat this process until the weight obtained third, fourth, fifth, and so on, until the weight of the flour obtained constant. Calculate the water content of the flour with the formula below:
Flour weight - Constant flour weight x 100%
Flour weight - Constant weighing bottle
To obtain a constant weight quickly, the thing to do is equate time appropriately at each stage of the process from heating to weighing for each weighing.
Another tool that used to heat the solution is evaporation dish porcelain. The tool is shaped like a bowl and made of white porcelain. Before and after using evaporation dish porcelain, the dish should be washed with water and then with soap and thoroughly with a brush tube. Last washed again with water and dried with a tissue or drained.
How to use the evaporation dish porcelain is, as an example for getting the salt powder from cucl2 solution, download CuCl2 solution of 10 ml, this solution is blue, then insert it into the evaporation dish porcelain. Turn on the bunsen and place the tripod and asbestos board or wire gauze thereon. Adjust the bunsen flame so that the flame produced a little red and blue, then place the evaporation dish porcelain containing the solution. Heat for 5 minutes and then raise the temperature of the fire into a blue flame. Heat for 10 minutes and then raise the temperature again so the fire into 2 layers, blue layers and green layers therein.
Heat the solution until all the water in the solution evaporates, leaving only solids or powders CuCl2. Heating by raising the temperature of the flame gradually, so the salt is not splashing out of evaporating dish porcelain. If the heating directly with a green flame inside a blue flame, then this solution will have a significant increase in temperature so that the energy in the solution will be pushed very strongly, and come out so cause splashes.
The next tool to use to heat a substance that is a crucible. This crucible shaped like a small cup with a lid that is the bottom diameter smaller than the diameter on top of it. Porcelain saucer made of white crucible. In crucible lids are small arch semicircles, which is useful as an ear to pick up the crucible lid.
Crucible can be heated over a bunsen flame directly or within the furnace that reaches a temperature of 1200°C. A crucible is usually used to determine the ash content of a substance with gravimetry method. Combustion ash is the residue of a substance that cannot longer be burned. ash usually contain only inorganic substances such as metals or other.
How to use a crucible for constant weighing is weighing crucible with an analytical balance in order to get the weight up to 4 digits behind the comma, for example 6.6345 gram. This is called the first weight. Hold a porcelain cup with a tongs during this process. Then turn on the bunsen and place a the clay triangle above tripod (as shown above). Place a crucible with lid on fire for 1 hour. Then chill on the clean table for 15 minutes, then insert it into a desiccator containing silica gel for 30 minutes.
Then take a crucible from the desiccator and weigh it again with analytical balance. So we get a second weight. Repeat the above process of heating up bunsen weighed in an analytical balance to obtain the third weight. If the weight of the second and third weight difference is not more than 1%, it has obtained a constant weight crucible. But if the difference is more than 1%, then repeat this process to obtain the weight of the fourth, fifth, and so on until a constant weight is obtained.
Then weighing 1.1346 gram sample of flour, for example, is called the flour weight, then heat over a bunsen with a small blue flame so that it becomes charcoal. then raise the fire into 2 layers (blue and green layer) and reheat to ashes. Then repeat the process until the weighing with analytical balance and weight of ash obtained first. Reheat over a bunsen for 1 hour and repeat the process until the second weight is obtained. if the first weight and the second weight difference is not more than 1%, it has obtained a constant weight of the ash. But if the difference is more than 1%, then repeat this process until the weight obtained third, fourth, fifth, and so on until the weight of ash obtained constant. Calculate the ash content of the flour with the formula below :
Ash constant weight – Crucible constant weight x 100%
Flour weight – Crucible constant weight
That's part of the tools used to heat a substance in accordance with their respective functions.
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