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Parthasaradhi M Member since Apr 1, Physical changes: While burning the candle the wax slowly melts as the candle gets smaller and this molten wax can be again solidified and will make it into a candle. 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. Q5 When a candle burns, both physical and chemical changes take place. Identify these changes. Give another example of a familiar process in which both the chemical and physical changes take place.
Book a free class. Book a free class Join class now already booked a class? Preparing to Investigate. Gathering Evidence. Record your obervations.
Qualitative observations Quantitative observations 1. Record your observations. Label the following regions of the candle in your drawing: solid wax liquid wax region of wick without flame region of wick with flame region of the wick that glows Now distinguish as many different aspects of the flame itself and label them in the drawing.
Interpreting Evidence. 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? Part Three. Reflecting on the Investigation.
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