Combustion

Fuel + O2 • CO2 + H2O + Energy

RELEVANCE

Experimental Design

• Overall Set Up• Can should be gripped

not crushed• Adjust tension and

height with clamp on the ring stand using thumb screws

Wick Length

• The wick should be trimmed to ~ ¼ of an inch.

• Done by “pinching” the burnt wick with fingernails.

• Long wicks droop causing the candle to burn quickly and unevenly.

Adjustments

• Wing nuts for adjustment

• Upright• Up and down• Tighten Clamp• 1-2 cm above

candle wick (½ to ¾ inch).

Heating

• Do not heat with thermometer in the can.

• Flame in the center can bottom

• Heat for ~7 minutes.

Drafts

• Drafts o minimize the contact o reduce efficiency and

heat transfero block drafts from

outside sources• The depression in the

bottom helps block some of the drafts.

• Don’t “breathe” on the candle.

• Some charring normal, especially when drafts interfere.

• Remove and extinguish the heat source before inserting the thermometer.

• Do not touch thermometer to bottom of can

• After burning o Measure masso Measure temperature

Clean Up

• Aluminum Cano Empty & place upside down on paper towelo Wipe off charring from bottom of can

• Clean Work Space with water & paper towel (residual soot)

• Refill DI water bottle• Sign and date conclusion and discussion

pages in ink

Question 2

• Specific Heat: C=1 cal/goCo 1 Calorie to raise

1 gram of water 1oC

o How many calories to raise 10 grams of water?

o 500 grams of water?

o Was the water in the can increased by just 1oC?

Zona

Question 2

• Specific Heat: C=1 cal/goCo What formula

should you use?

o What do the component of the formula represent?

Swanson

Question 3

• Calories/g • Joules/g

• How many kJ/g?

• Experimental to theoretical?

• What % efficiency?

Zona

Question 3

• What conversions are necessary?

• What is your experimental energy?

• Experimental to theoretical?

• What % efficiency?

Swanson

Question 4

• Molar Ratio?• Molar Mass of

Candle• Mass of

Candle?• Mass Candle

=Mass CO2

C25H52 + O2 • CO2 + H2O

Zona

Question 4

• Molar Ratio?• Molar Mass of

Candle? of CO2?

• What conversions are needed?

C25H52 + O2 • CO2 + H2O

Swanson

Question 5

• How many joules produced?

• How long did the candle burn?

Zona

Question 5

• How many joules produced?

• How long did the candle burn?

Swanson