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Usually, the more luminous or yellow a flame, the less efficient the burn process is.
This can be compared to a properly adjusted gas stove. The flame is fully blue with no yellow, and minimal luminosity.
When a flame is yellow (assuming typical fuels of things like candles, alcohol, and NG, etc.), it indicates incomplete combustion. Natural gas (NG) is very clean burning, but requires the proper amount of oxygen (air) in order to do so. This is why, for example, to properly adjust a gas furnace. Properly adjusted, the flame is all blue. Improperly adjusted, or clogged air inlets cause the flame to turn yellow. A dangerous side effect of incomplete combustion is the production of CO or carbon monoxide. This is carbon "without enough oxygen". Blue flames have enough oxygen and produce CO2 (and water), or carbon <u>dioxide</u> which is much less dangerous to life then CO.
When something like a test tube is placed in the flame, the much cooler glass condenses and catches the product of incomplete combustion - carbon.
So the black coating is basically all carbon.
Usually this coating will wash off easily on smooth lab glassware.
To prevent it from occurring, the flame source needs more oxygen, i.e. more air and possibly a cleaner fuel source. This requires an apparatus other than a plain wick (as in a Bunsen burner) and includes holes under the flame area to draw in enough air to fully burn the fuel.
Also some fuels are not clean burning as in paraffin or candles. other fuels like natural gas, or propane can easily be made to burn clean with a fully blue flame. This would have close to zero carbon content and would not turn the test tube black.
Examples of a clean blue flame would be again, a gas stove, and a propane torch, which uses the propane flow from a jet, to draw in air before it reaches the flame. This results in the typical light, to dark blue flame and is very clean.
What else can I help you with?
Which bunsen burner luminous or non luminous flame used in laboratory and why?
A non-luminous flame is typically used in laboratory settings when using a Bunsen burner. This flame produces a more controlled and homogeneous heat source, making it ideal for processes like heating, sterilizing, and combustion analysis. The non-luminous flame also produces less soot and is more energy efficient compared to a luminous flame.
What is appearance of a flame that is used for heating?
luminous
What happens if you use a luminous flame to boil water in a test tube?
Using a luminous flame to boil water in a test tube can lead to incomplete combustion, resulting in the formation of soot or carbon particles that may contaminate the water. It may also affect the purity of the water due to the combustion products in the flame. It is recommended to use a clean, blue flame for heating applications in the laboratory to avoid this issue.
When using a Bunsen burner why do you use the blue flame for heating?
The blue flame in a Bunsen burner is used for heating because it indicates complete combustion of the fuel, resulting in a high-temperature, clean, and efficient flame. This flame is ideal for heating as it produces a steady and controlled heat source for various laboratory applications.
How can you heat and expand metal without using a flame of any kind?
One way to heat and expand metal without using a flame is to use induction heating. Induction heating uses an electromagnetic field to heat the metal through induction, causing it to expand. This method is often used in industrial applications where precise and controlled heating is required.
Should a luminous or non luminous Bunsen flame be used for heating in the laboratory and why?
Non-luminous flame should be used for heating in the laboratory because the flame is steady and produce little or no soot.Non-luminous flame is very hot thus, it is recommendable to use for laboratory purposes.Luminous flame is unsteady while non-luminous flame is steady.Another reason of using non-luminous flame because the flame of non-luminous is blue, and not visible unlike the luminous flame which is yellow in colour and visible.
Which bunsen burner luminous or non luminous flame used in laboratory and why?
A non-luminous flame is typically used in laboratory settings when using a Bunsen burner. This flame produces a more controlled and homogeneous heat source, making it ideal for processes like heating, sterilizing, and combustion analysis. The non-luminous flame also produces less soot and is more energy efficient compared to a luminous flame.
Is non luminous flame steady or unsteady?
Non-luminous flame should be used for heating in the because the flame is steady and produce little or no soot. Non-luminous flame is very hot thus, it is recommen- dable to use for laboratory purposes. Luminous flame is unsteady while non-lumi- nous flame is steady. Another reason of using non-luminous flame because the flame of non-luminous is blue, and not visible unlike the luminous flame which is yellow in colour and visible.
Characteristics of luminous flame?
Non luminous zone is the zone of a flame which is also the hottest zone of the flame as it is mostly in contact with oxygen. It is also called invisible zone.
What is appearance of a flame that is used for heating?
luminous
What is luminous flame and Explain why it takes a longer time to heat equal amount of water using a luminous flame?
yellow color in a luminous flame produces soot or carbon. carbon dioxide is present in the luminous flame but when its combined with oxygen the flame is nonluminous which is in a blue color. it takes a longer time because luminous flame is cooler than the nonluminous. I only know what luminous flame is. The inner part of luminous flame is blue while the outer part of the luminous flame is yellow. It is unsteady. Yeah. Carbon Dioxide is only present in the luminous flame. When oxygen is combined with the flame, the flame will become non- luminous which is inner and outer part are blue. Hmm. Actually luminous flame's hottest part is at the bottom while non- luminous flame hottest part is at the middle and the top. That's all i know. If i know more, i will update for you. Thank you! By helpingppl
What happens if you use a luminous flame to boil water in a test tube?
Using a luminous flame to boil water in a test tube can lead to incomplete combustion, resulting in the formation of soot or carbon particles that may contaminate the water. It may also affect the purity of the water due to the combustion products in the flame. It is recommended to use a clean, blue flame for heating applications in the laboratory to avoid this issue.
What time does it take to boil the water if you use luminous flame?
Depends mainly on the amount of water and the starting temperature and the measure of the flame.
Why is it necessary to use non-luminous flame in flame test?
Using a non-luminous flame in a flame test ensures that the color produced is due to the metal ion itself and not any additional color from the burning fuel. This allows for accurate identification of the metal ions present in the sample based on the specific color produced in the flame.
Why is it advisable to put off a non luminous flame when not in use?
Non- Luminous can burn efficiently because luminous flames don't burn as efficiently as non-luminous ones, they don't produce as much energy. This means that the non-luminous flames have a lot more energy than luminous ones, and their flames are actually hotter. This is why the luminous ones look yellow and the non-luminous ones look blue. Hotter flames burn blue and (relatively) cooler ones burn yellow.
When using a Bunsen burner why do you use the blue flame for heating?
The blue flame in a Bunsen burner is used for heating because it indicates complete combustion of the fuel, resulting in a high-temperature, clean, and efficient flame. This flame is ideal for heating as it produces a steady and controlled heat source for various laboratory applications.
Can you melt ionic compounds in a Bunsen burner flame?
It is not recommended to melt ionic compounds using a Bunsen burner flame because the intense heat can lead to decomposition of the compound or produce toxic fumes. It is safer to use a method like heating in a crucible with a low flame or using a heating mantle for melting ionic compounds.
