Title: Quantitative Observations of a Chemical Reaction
Purpose: Make a quantitative investigation of a chemical reaction.
Materials and Apparatus: laboratory balance; graduated cylinder (100mL); ring stand; stopwatch;
iron ring; plastic square; wire gauze; safety goggles; thermometer; lab apron; beaker (250mL);
candle (2-cm diameter); matches (2 or 3)
Drawings:
Procedures and Observations:
Procedures: The first thing to do is to find the mass of the candle using a balance. Then measure
exactly 100mL of tap water into the graduated cylinder. Pour this water into a 250mL beaker and
place the beaker on wire gauze. After that, measure the temperature of the water and record.
Light the candle and place it on the plastic square. The height of the ring should be adjusted so
that the flame is 2cm below the base of the beaker. By using the candle, heat the water for a
minimum of 10 minutes. Record the temperature at every minute. Then extinguish the flame and
measure the temperature of the water and the mass of the candle. Record all observations.
Relight the candle and repeat the above steps for a second trial.
Observations: The observations were that the mass after the candle burned was only 0.1g
different between the two trials. Another observation was that the final temperature of the water
for both trials went up exactly 28 ̊ C from the beginning temperature of the water.
Data:
Trial 1
Trial 2
20.55g
19.56g
Mass of candle after burning 19.56g
18.47g
Original mass of candle
10 min.
10 min.
water
20 ̊ C
22 ̊ C
Final temperature of water
48 ̊ C
50 ̊ C
Time water heated
10 min.
10 min.
Time candle burned
Original temperature of
Calculations:
1. Original mass of candle – mass of candle after burning = change in mass of candle
20.55g – 19.56g = 0.99g
19.56g – 18.47g = 1.09g
2. Change in mass of candle / time candle burned = change in mass of the candle per min.
.99g / 10 min. = 0.099g per min.
1.09g / 10 min. = 0.109g per min.
3. Final temperature of water – original temperature of water = change in water temperature
48 ̊ C – 20 ̊ C = 28 ̊ C
50 ̊ C – 22 ̊ C = 28 ̊ C
4. Change in water temperature / time water heated = change in water temperature per min.
28 ̊ C / 10 min. = 2.8 ̊ C per min.
28 ̊ C / 10 min. = 2.8 ̊ C per min.
Conclusions: The experiment was a success. Quantitative measurements of the chemical
reactions were observed and recorded. What was noticed was that the results from Trial 1 were
very similar to the results from Trial 2. There was very little interference, the experiment went
right as planned, and a lot of data was recorded.
Error Sources: The only error that was encountered was at approximately 8 minutes of the 2nd
trial when a group from across the lab table accidentally extinguished the flame when
extinguishing theirs. The stopwatch was stopped, the candle was relit, and then the time was
started again from where it left off.
Questions:
1. Compare your trial results and calculations with those of other lab teams. Are your
results exactly the same? How do you account for any differences in data? If one set of
data differs from another in an experiment, does this mean that one or both sets are
wrong? Explain your answer.
No, the results are not exactly the same. The difference in data could occur from the
starting mass of the candles, the different starting temperatures of water, and if the flame
was closer or farther from the bottom of the beaker. If one set of data differs from another
in an experiment it does not mean any data is wrong it just means that a possible
unknown factor could have altered the data.
2. What does the term rate mean? a. What was the rate of the burning of the candle? b.
What was the rate of heating the water?
A term rate is a measure, quantity, or frequency, typically one measured against some
other quantity or measure. The rate of the burning candle was .099 grams per minute. The
rate of the heating water was 2.8 degrees Celsius per minute.
3. Explain how the heat from the combustion reaction is related to the temperature change
of the water.
When a reaction gives off heat the environment surrounding the reaction will absorb the
heat. If it happens to be water, the heat is absorbed and the water temperature increases.
4. Outline a laboratory procedure that would determine which produces more heat – a
gram of candle wax or a gram of alcohol. How could this type of experiment be used to
decide which substance would make the better fuel? What other factors might enter into
choosing a fuel?
The first step to take while going about this experiment would be to set up a graph with
the x axis being time and the y axis being temperature. Pick a designated amount of time
(about 5 minutes minimum) and record the temperature every 30 seconds to a minute.
Then when the time is up compare the results and make a conclusion. After this, another
experiment could be done to see how long the wax and the alcohol burn before going out.
The conclusions together could give the best fuel source. Other factors that could affect
the choice of fuel are the size of the area that is being heated and the humidity in that
given area.
Colby Geisinger
Keegan Fouse
Frank Melvin