Teacher"s Overview


In this investigation, students are challenged to make cautious observations about a burning candle to discover the chemical and also physical transforms that make it work.

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Students will certainly desribe your observations around a burn candle to discover the chemical and physical alters that make it work.


Be certain to wear safety and security goggles if making nearby observations, tie your hair earlier if you have actually long hair, and always be mindful of where the fire is with respect to your clothing—do no lean over the flame.Burning candles are open up flames that can cause burns. Liquid wax is hot and also can cause burns to the skin.

Materials because that Each Group

Tea irradiate candleMatchesSmall manufacturer or evaporating food (such together 50 mL or 100 mL)BalanceRuler or meter stickString (for measure circumference)Stopwatch

Time Required

One course period, about 45–50 minutes.

Lab Tips

Tea candles can be to buy in large quantities, as have the right to tapered candles from hardware stores. Candle of different colors, sizes, and shapes deserve to enrich the observations made through the class.

We are all acquainted with burning candles, however how much have we really seen while looking at one? In this practice you will certainly be tested to observe a burn candle v the lens that chemistry. You may be surprised by exactly how much is really happening in what seems prefer a familiar process!

First us will try to observe details beyond our usual means of looking at a candle, and also then we will look for proof of the physics or chemical nature of any kind of changes that room taking place. Take care in recording her observations—try come imagine the you have never watched a burning candle before!

Obtain a tea light candle, matches, and also any measuring equipment obtainable to you. Before lighting the candle, make three qualitative observations and three quantitative monitorings of the candle.Qualitative monitorings describe characteristics or characteristics, quantitative monitorings involve quantities, or measurements. You might choose among many nature to observe: color, texture, mass, physics dimensions, density, aroma… or any type of others you deserve to think of. Usage as numerous of your physical senses together possible, and also be certain to include units for any kind of of your quantitative observations.

Use a match to very closely light the candle.Repeat the procedure of do qualitative and quantitative observations of the burning candle, this time making 6 of each type of observation. (Some of your observations might relate to properties you have already recorded, that may be transforming now that the candle is burning.) once again use all your senses to make qualitative observations. Ask yourself what you have the right to measure because that the quantitative observations.

For your observations and measurements, think about not only the physical candle, but additionally consider its affect on the wait in the room surrounding it.

Now lay out a in-depth drawing that the burn candle, an enlargement of the part about a centimeter from the optimal of the candle come the topmost tip of the flame:

Label the following regions the the candle in her drawing:

solid waxliquid waxregion that wick there is no flameregion of wick through flameregion that the wick the glows

Now differentiate as numerous different elements of the flame itself and label lock in the drawing. As soon as you have actually completed recording her observations and also drawings, prepare to blow the end the candle, and also be all set to make additional observations together you execute this!Blow the end the candle and record 2 qualitative and two quantitative observations of the candle automatically after it is extinguished:

Qualitative observationsQuantitative observations

Interpreting Evidence

component One

Now that we have actually paid close fist to the nature of a burning candle, we can start to translate what we’ve viewed in terms of phase changes and also chemical reactions.In a phase change (from heavy to fluid or from liquid to gas) the particles of a problem (in this instance the molecule of wax) will readjust the plan they have with every other. Together a solid they will be carefully packed together and also unable to relocate freely. In the fluid they will be able to flow around each other however will still be close together, and also as a gas they will certainly fly freely apart however they will still it is in wax molecules and will have actually the same structure they had as molecule in the solid and the liquid phases:


waxes from plants and also animals have different structures. Right here is a molecule similar to wax— a material that is typically a significant component the the candle wax.

In the crate below, use small, solitary shapes come represent whole wax molecules, and also sketch their plan in the three physical phases:


based on your observations of the burn candle, walk you find evidence for the readjust from the hard wax step to the fluid wax phase?


describe this proof as specifically as possible.


explain this evidence as especially as possible.

Did you uncover evidence for the readjust from the fluid wax step to the gas wax phase?

A physical candle is composed of wax neighboring a wick. Look up the an interpretation of the verb “to wick,” and write it down.Describe the wicking procedure in the burning candle, and also be sure your description has the physics state that the wax and the wick.As a candle burns, the wax progressively disappears from sight. Is over there a physical readjust in the wax that would account for this disappearanceIf the wax was merely undergoing physics change, would you suppose the candle to develop heat and light as it does once a candle burns?The procedure of burn (as protest to evaporating) is a chemistry reaction, a chemistry change. The wax molecules room undergoing a chemical change; they are transforming into various molecules through reacting with a substance in the air. What is this substance in the air that a candle requirements to burn?

Interestingly, a candle releases power through the same kind that reaction the your body supplies to acquire energy. Hold your breath because that a moment. What is your body craving? This is the exact same substance the candle demands to burn in a chemical change that we call combustion.

We deserve to represent the burning of a candle prefer this:


complete the adhering to sentence the restates this equation:

Two molecule of wax react through ____________ molecules of oxygen to produce__________ molecule of _____________________________ and also ___________ molecule of __________________.

We room not conscious of oxygen in the air because it is an odorless and colorless gas, and at the temperature of a burning candle, both the CO2 and the H2O are also gases that space invisible come us. We can see evidence of chemical change, however, if we restrict the amount of oxygen the is enabled to react v the wax.

If much less oxygen is available, one possible outcome in the burning of wax is

Relight the candle and also lower the bottom of a little beaker or a clear watch glass into the flame so that the flame touches the surface ar of the glass. Host it there for a minute (where it restricts several of the air flow to the flame) and then eliminate it.

What do you observe on the bottom the the beaker? What might this problem be and where did it come from?How go this provide evidence that a chemistry reaction is acquisition place?Wipe the bottom the the manufacturer clean and place an ice cube within it. Organize the beaker numerous centimeters over (not in) the fire and allow the candle to burn. Can you check out a substance forming on the bottom that the beaker? What can this problem be and where did that come from? can it have actually come from the melting ice cream inside the beaker?Consider the fire itself. Is the fire a substance created by the candle? What observations lead you to think that the flame is matter? In what means does the flame seem like energy?Is the adhering to statement true or false: “As a candle burns, wax turns right into fire.” If this isn’t precise statement, can you restate it correctly?

Finally, let us consider the physical step of the wax together it reacts v the oxygen to develop carbon dioxide and water. Prepare to watch carefully! Blow out the candle and an extremely quickly lug a enhance close come the wick. Try to an alert exactly whereby the lit wooden splint is with respect to the wick when the candle reignites.

Do this several times to view if you watch something interesting. Note any type of evidence you have actually observed that helps to identify the physical phase of the wax as soon as it reacts v oxygen.

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What step is the wax in as soon as it mixes with oxygen in the air and also undergoes a chemistry change?Based on her observations, in which phase (solid, liquid, or gas) is the wax most likely to undergo a chemistry change?Explain why this is the case based upon your sketches the wax in solid, liquid, and also gas phases.How can this (your price to inquiry above) describe a authorize that says NO SMOKING close to the pumps in ~ a gas station?Look back at her diagrams that the candle flame. Have the right to you determine the region where the wick chin is experience combustion? whereby is this region?What is fire? Is it matter or is that energy? explain your answer.In a short paragraph, summary the changes that a candle undergoes as soon as it burns. Combine the following words right into the i in a systematic way: wax, wick, step change, chemistry reaction, vaporize, melt, transforms, solid, liquid, gas, energy, light, and heat.