Table of Contents
What happens when an evaporating dish is heated?
A relatively large liquid surface promotes evaporation. If heated in a flask or beaker, a part of the evaporated liquid condenses on the vessel walls and flows back into the solution. This does not happen in a dish….Evaporating dish.
| Three evaporation dishes in various sizes | |
|---|---|
| Other names | Evaporating basin |
| Related items | Crucible |
What precautions need to be taken when heating a solution?
1 Answer
- Always wear safety glasses.
- Always point the test tube away from any other person in the lab.
- Heat the test tube being held at an angle so there is a way for the gases produced to escape safely.
- Heat the test tube at the top of the solution not the bottom where a gas bubble can cause an explosion.
How do you heat an evaporating dish?
Since they are thermally stable evaporating dishes may be heated to dryness over a Bunsen burner flame, in a laboratory oven, or on a hot plate with minimal concern of shattering. Quenching of hot porcelain should NOT be attempted. The evaporating dish should be allowed to air cool completely before handling.
What safety precautions should be used when heating water in a glass container?
Heating Safety 1) Turn off heat sources when they are not in use. 2) Point test tubes away from yourself and others when heating substances in them. 3) Use the proper procedures when lighting a Bunsen burner. 4) To avoid burns, do not handle heated glassware or materials directly.
What was left on the evaporating dish?
When a solution is heated, the solvent evaporates, leaving behind the dissolved solids as residue. Only the solute will remain in the evaporating dish. Example: water and salt. P.S. Evaporation to dryness cannot be use for solutions like sugar solution because the sugar will decompose upon heating.
Why was the solution heated before it was left in an evaporating dish?
Heating the solution will cause the temperature of the salt solution to increase. By increasing the temperature of the salt solution, the rate of evaporation will increase. Evaporation is the change of a substance from a liquid phase to a gaseous phase.
Which safety precaution is recommended when a liquid is being heated in a test tube?
Q. Which safety precaution is recommended when a liquid is being heated in a test tube? When holding the test tube, keep fingers closest to the open end of the tube. Direct the flame of the burner into the open end of the test tube.
What will be left in the dish when heating is completed?
When a solution is heated, the solvent evaporates, leaving behind the dissolved solids as residue. When a solution containing dissolved solutes is heated, the solvent will evaporate. Only the solute will remain in the evaporating dish.
How big of an evaporation dish is needed?
Evaporation dish capacities are usually less than10 mL, but larger, more hemispherical dishes can be used to accommodate larger liquid volumes. When evaporating dishes are used, gas burner heating is preferred; evaporating dishes should never be placed on a hot plate.
Is it OK to put evaporating dishes on a hot plate?
When evaporating dishes are used, gas burner heating is preferred; evaporating dishes should never be placed on a hot plate. Always handle heated dishes carefully to avoid getting burned, because they may not appear to be hot.
Why do we use the evaporating dish for drying?
The solid that is obtained needs to be dried in the drying oven, and we commonly use the evaporating dish for this because of its high resistance to heat. The drying and weighing process is repeated until a relatively constant weight is reflected on an analytical balance.
How are evaporating dishes used in chemistry lab?
The evaporating dishes we encounter in a chemistry lab usually accommodate small samples. However, bigger samples can be accommodated using larger capacity evaporating dishes – these are less shallow and more hemispherical in shape to accommodate larger volumes of liquid.