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Solution: Melting of wax is temporary and wax can settle again on cooling and turns into a solid. Hence, the change is only physical and the state of matter changes. Burning of the candle is permanent because once it is burnt it cannot be converted into the candle.
What is the meaning of melting of wax?
Melting of wax is physical change. In melting of wax, only the state of wax changes from solid to liquid. It is a reversible reaction and no new substance is formed. Burning of candle is both physical and chemical change. When the candle burns, the wax slowly melts which freezes after some time (Physical change).
Does wax melt or burn?
Candle Wax Combustion When you light a candle, wax near the wick melts into a liquid. The heat of the flame vaporizes the wax molecules and they react with the oxygen in the air. The heat maintains the reaction, vaporizing wax so that it can burn, melting it to maintain the supply of fuel.
What is the difference between burning of a candle?
Class 8 Question Candle burns with a flame but coal does not burns with a flame also coal is a carbon product and its burning is harmful for environment but candle is made from wax its burning is not as much harmful as burning of coal .
Is melting of candle wax a permanent change?
Melting of wax is temporary and wax can settle again on cooling and turns into a solid. Hence, the change is only physical and the state of matter changes. Burning of the candle is permanent because once it is burnt it cannot be converted into the candle.
Is wax melting physical or chemical?
The process of a solid becoming a liquid is called melting. Melting of wax, by itself, involves a change of state from solid to liquid. When the physical state of a substance changes, no new products are formed. Hence, melting of wax is physical change and the correct answer is option A.
Where does wax go when it burns?
When you light up the candle, the wax is what actually burns into the air. Thanks to the principles of capillary action, the wax is drawn up the wick (the wick usually runs the entire length of the candle), and it evaporates as the flame reaches around 200 degrees Celsius.
How many times can you use a wax melt?
How many times can you reuse wax melts? According to Happy Wax, two or three wax melts provide about 8 hours of fragrance. Different brands have different burn times, but most fall within the 6-8 hours range. Many people find they can reuse the same wax melts several times before the scent slowly disappears.
Can wax burn without a wick?
So why does a candle need a wick? If you try to light a lump of wax you can melt the wax but that is just about all that happens. The wick does the important job of keeping the molten wax in the heat of the flame long enough to vaporize. Liquid wax does not burn.
Why air is essential for burning explain with diagram?
This diagram shows air is essential for combustion by analysing following points: a) The candle burns freely due to presence of air. (b) The flame flickers and produces smoke because there is no air in case. (c) In case flame finally goes off because air is not available.
What is difference between burning of a candle and burning of coal?
When the candle burns, the wax melts and changes to its liquid form. The molten wax then rises through the wick and burns in the form of vapour and as a result produces flame. But in the case of coal, when it burns it doesn’t turn into vapour. So the burning of coal does not produce any kind of flame.
What is difference between the burning of a candle and burning of a fuel like coal?
A candle burns with a flame but coal does not burn with a flame. Also, coal is a carbon product and its burning is harmful to the environment but the candle is made from wax its burning is not as harmful as burning of coal.
What change in phase happens when candle melted?
When you light a candle, the heat of the flame melts the wax near the wick. This liquid wax is then drawn up the wick by capillary action. The heat of the flame vaporizes the liquid wax (turns it into a hot gas), and starts to break down the hydrocarbons into molecules of hydrogen and carbon.
Is melting of wax reversible or irreversible change?
An irreversible change is a permanent change that cannot be undone. Melting of wax is a reversible process. Since upon cooling, it changes back to solid wax. Similarly, Solidification of melted wax can be reversed which is the melting of wax.
Is burning of candle wax when heated a chemical reaction?
When a candle burns, the oxygen in the air reacts and forms carbon dioxide. A new substance, the CO2 is formed. So it is a chemical change. When the candle melts, no new substance is formed and the molten wax can be again solidified and made into a candle.
Is frying an egg a chemical change?
New chemical bonds form between the uncurled egg white proteins. When chemical bonds are broken or formed, new particles are created. Therefore, frying an egg is a chemical change because it results in the formation of new particles.
Is melting of butter a chemical change?
No change in the chemical composition occurs when it is melted. Thus, melting of butter is a physical process because the physical appearance of the butter changes, the change is visible to eyes, the change can be reversed and no chemical change occurs.
Is mixing a teaspoon of instant coffee?
We usually recommend stirring our coffee in hot water first, but we always learn new ticks too! Mix a teaspoon of cold water with a teaspoon of the instant coffee in your mug. Keep mixing until all of the instant coffee is dissolved. Then pour the mix over hot water and stir more.
What burns in a candle?
The combustible material in a candle—or its fuel—is the wax. As the wick burns down the heat of the flame melts the wax around the wick. Because the wick is absorbent it sucks the liquid wax into the wick and upward into the flame. Once the liquid wax gets hot enough, it then turns from a liquid into a gas.
Is candle wax safe to breathe?
When burned, paraffin wax can release toxic volatile organic compounds (VOCs) into the air including acetone, benzene and toluene, which are known carcinogens. These are the same chemicals found in diesel fuel emissions and are known to cause allergies, asthma attacks and skin problems.
What state was the wax in before it was heated?
The state of wax is solid before melting, which on heating converts to liquid wax.
