Part One. Waxes from plants and animals have different structures. Here is a molecule similar to wax— a material that is normally a major component of the candle wax. Describe this evidence as specifically as possible. Did you find evidence for the change from the liquid wax phase to the gaseous wax phase? A physical candle is composed of wax surrounding a wick. Describe the wicking process in the burning candle, and be sure your description includes the physical state of the wax and the wick.
As a candle burns, the wax gradually disappears from sight. Is there a physical change in the wax that would account for this disappearance If the wax was simply undergoing physical change, would you expect the candle to produce heat and light as it does when a candle burns? The process of burning as opposed to evaporating is a chemical reaction, a chemical change. The wax molecules are undergoing a chemical change; they are changing into different molecules by reacting with a substance in the air.
What is this substance in the air that a candle needs to burn? Part Two. We can represent the combustion of a candle like this:. If less oxygen is available, one possible outcome in the combustion of wax is.
What do you observe on the bottom of the beaker? What could this substance be and where did it come from? How does this provide evidence that a chemical reaction is taking place? Wipe the bottom of the beaker clean and place an ice cube inside it. Hold the beaker several centimeters above not in the flame and allow the candle to burn. Can you see a substance forming on the bottom of the beaker? Could it have come from the melting ice inside the beaker?
Consider the flame itself. Is the flame a substance produced by the candle? What observations lead you to think that the flame is matter? In what ways does the flame seem like energy? Examine data relating to the structure and complexity of compounds, including mass, infrared and NMR spectra, in this workshop lesson plan for 16—18 year olds.
Discover the methods and conditions used by chemical scientists to grow protein crystals in this lesson plan with activities for 14—16 year olds. Site powered by Webvision Cloud. Skip to main content Skip to navigation.
Lesson plans. No comments. The activities in this lesson plan are designed to deal explicitly with any confusion that may exist between the ideas of burning, melting and evaporating and, in particular, to check on the following misconceptions: When a candle burns the burning wick melts the wax which runs away.
When a candle burns the burning wick evaporates the wax into the air. Learning objectives Students will be able to: Describe and explain what happens when a candle burns.
Sequence of activities Introduction and demonstration Light a large candle and ask students how it will be different if it is left to burn for an hour to establish the idea that the candle will get shorter as it burns. Share the learning objective for the session. Circulate and support with prompts while students: Work in pairs. Collect a candle, light it and observe what happens over three or four minutes.
Swap diagrams with their partner. Hand the sheets back again and discuss the comments on each. Circulate and support with prompts while students: Look at the suggested explanations for why a burning candle gets shorter.
In their pairs decide on which explanation they feel is most likely. Rule out any explanation which they feel sure is not right. Write down the agreed views on their copy of the sheet. Nutrition in Plants. Nutrition in Animals. Fibre to Fabric. Acids, Bases and Salts. Physical and Chemical Changes. Weather, Climate and Adaptations of Animals to Climate. Winds, Storms and Cyclones. Respiration in Organisms. Transportation in Animals and Plants. Reproduction in Plants.
Motion and Time. Electric Current and its Effects. Water: A Precious Resource. Forests: Our Lifeline. Wastewater Story. That reaction requires something to burn the wick , oxygen in the air , and heat to initiate. When the heat provides enough energy to the wick, the wick wants to react with the oxygen to form carbon dioxide and water molecules, releasing energy in the process in the form of a flame. A candle, however, is more than just wick. The wax is there to slow down the burning of the wick and provide a rigid structure that prevents the flame from falling and spreading fire.
The wax is more resilient to the flame so it doesn't catch fire; instead, it melts. Tavin great question! There are two parts of a candle, the wick and wax. First the wick, made of rope or twine, is lit. The heat from flames melts the wax. As in paper towels soaking up water, the wick pulls melted wax upward. The flame turns the liquid wax to vapor, which burns.
The wax also cools the wick so the wick burns slowly.
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