Chemistry
First Lab Report
Purpose:
Make a quantitative investigation of a chemical reaction.
Materials:
The candle was melted onto the aluminum lid and the mass was recorded. One hundred mL of tap water was measured in a graduated cylinder, which was poured into a 250 mL beaker. The beaker was placed on wire gauze, which was on the iron ring. The initial temperature of the water was recorded. The candle was lit under the beaker, and the iron ring adjusted, so the beaker’s base was 2 cm above the flame. The water was heated for 10 minutes and the flame was extinguished at the end of that time period. The water’s temperature and the mass of the candle were measured and recorded. The beaker water was poured out and rinsed in order to perform the second trial. The process was repeated one more time for the second trial.
Data:
Trial 1
Trial2
Original mass of candle
36.6g
35.71g
Mass of candle after burning
35.71g
34.96g
Time candle burned
10 min
10 min
Original temperature of water
23°c
23°c
Final temperature of water
44°c
40°c
Time water heated
10 min
10 min
Calculations:
Change in mass of the candle
Change in mass of the candle per minute
Change in temperature of the water
Change in temperature of the water per minute
Questions:
Pre lab:
The purpose of this lab was to make a quantitative investigation of a chemical reaction between a burning candle and a beaker filled with water at room temperature (eventually being heated by the candle). A 250 mL beaker was filled to 100 mL of tap water and put on wire gauze on top of a metal ring stand. A candle was lit underneath the beaker, so the flame of the candle was exactly 2 cm away from the beaker’s base. After 10 minutes, the flame would be extinguished. Then, measurements would be taken of the candle’s mass and the water’s temperature, before and after the reaction. This was in order to determine the difference of the water’s temperature due to the chemical reaction of the burning candle. There were also two trials in order to get more accuracy in the data.
The data shows the measurements of the candle’s mass and water’s temperature before and after 2 trials in the experiment. In the first trial before the chemical reaction, the original mass of the candle was 36.6 grams and after being burned for 10 minutes reduced to 35.71 grams, a 0.89 grams difference. The original temperature of the water in this trial was 23°C and after 10 minutes increased to 44°C, a 21°C increase. In the second trial the experiment was repeated and the results were similar. The original mass of the candle before being burned was 35.71 grams and decreased to 34.96 grams after 10 minutes of burning, a 0.75 grams difference. The original temperature of the water was 23°C and rose to 40°C, a 17°C increase. In this experiment, the data shows how the candle melted in each trial due to the wick inside it burning, and the heat from this chemical reaction caused the water to increase in both trials, as well, due to the transfer of exothermic heat from the flame to the water filled beaker. The experiment achieved the purpose of the lab due to the fact the candle burned, which is a chemical reaction, and heated the water from room temperature to a greater degree.
Make a quantitative investigation of a chemical reaction.
Materials:
- Laboratory
balance
- Ring
stand
- Wire
gauze
- Graduated
cylinder, 100mL
- Watch
or clock with second hand
- Safety
goggles
- La
apron
- Thermometer
- Beaker,
250mL
- Candle
(2cm diameter)
- Matches
- Aluminum
lid
The candle was melted onto the aluminum lid and the mass was recorded. One hundred mL of tap water was measured in a graduated cylinder, which was poured into a 250 mL beaker. The beaker was placed on wire gauze, which was on the iron ring. The initial temperature of the water was recorded. The candle was lit under the beaker, and the iron ring adjusted, so the beaker’s base was 2 cm above the flame. The water was heated for 10 minutes and the flame was extinguished at the end of that time period. The water’s temperature and the mass of the candle were measured and recorded. The beaker water was poured out and rinsed in order to perform the second trial. The process was repeated one more time for the second trial.
Data:
Trial 1
Trial2
Original mass of candle
36.6g
35.71g
Mass of candle after burning
35.71g
34.96g
Time candle burned
10 min
10 min
Original temperature of water
23°c
23°c
Final temperature of water
44°c
40°c
Time water heated
10 min
10 min
Calculations:
Change in mass of the candle
Change in mass of the candle per minute
Change in temperature of the water
Change in temperature of the water per minute
Questions:
Pre lab:
- Identify
a physical change and a chemical change in this demonstration
A physical change is the flame getting bigger or the candle getting smaller. A chemical change is the candle burning. - Was
the chemical reaction endothermic or exothermic?
The reaction was exothermic. - As
the candle burns, it becomes shorter. Where does the wax go?
The wax turns into CO₂ and H₂O. - What
was the role of the wick in the candle
It was used to draw up the wax to keep the candle burning. - In
the lab, the candle will be used to heat water. What other fuel sources can be
used to heat the water?
A burner, coal, and solar energy could all be used to heat the water.
- 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?
The results are not all the same. This can be accounted for human error such as not having the flame exactly 2cm below the water. - If
one set of data differs from another in an experiment does this mean that one
or both sets are wrong? Explain your answer.
If one set of data does not match another it does not mean that one or both are wrong. Both may be right if both experiments were followed in the same steps, even though the results are different due to the different masses/sizes of the candles. However because the results differ, it means that small errors may have occurred.
- Explain
what the term “rate” means. Determine the average rate of a burning candle and
the heating water.
The term rate describes the ration of two measurements and how the relate to each other during a certain period of time. The average rate of a burning candle was 0.082g/minute. The average rate of heating water was 1.9°C/minute. - Explain
how the heat from the combustion reaction is related to the temperature change
of the water?
The heat from the combustion reaction is related to the temperature change of the water because it depends on how much heat the candle is giving to the water. The more heat from the reaction means that there is a more temperature change. The less heat from the reaction means that there is a less temperature change. It is directly related. - How
would you determine which fuel produces more heat - a gram of wax or a gram of alcohol.
Outline a laboratory procedure that would determine this. 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?
To determine which fuel produces more heat, burn the candle wax and alcohol simultaneously. Place two beakers on two iron rings to heat up both 100 mL of water for 10 minutes. Measure the temperature of the water of both. This will show which produced more heat and which stayed the longest to produce heat. The candle would be better because it would not die out as quickly and most likely could produce more heat than the alcohol in a longer period of time. It also depends on which fuel would be the easiest to transport from place to place.
The purpose of this lab was to make a quantitative investigation of a chemical reaction between a burning candle and a beaker filled with water at room temperature (eventually being heated by the candle). A 250 mL beaker was filled to 100 mL of tap water and put on wire gauze on top of a metal ring stand. A candle was lit underneath the beaker, so the flame of the candle was exactly 2 cm away from the beaker’s base. After 10 minutes, the flame would be extinguished. Then, measurements would be taken of the candle’s mass and the water’s temperature, before and after the reaction. This was in order to determine the difference of the water’s temperature due to the chemical reaction of the burning candle. There were also two trials in order to get more accuracy in the data.
The data shows the measurements of the candle’s mass and water’s temperature before and after 2 trials in the experiment. In the first trial before the chemical reaction, the original mass of the candle was 36.6 grams and after being burned for 10 minutes reduced to 35.71 grams, a 0.89 grams difference. The original temperature of the water in this trial was 23°C and after 10 minutes increased to 44°C, a 21°C increase. In the second trial the experiment was repeated and the results were similar. The original mass of the candle before being burned was 35.71 grams and decreased to 34.96 grams after 10 minutes of burning, a 0.75 grams difference. The original temperature of the water was 23°C and rose to 40°C, a 17°C increase. In this experiment, the data shows how the candle melted in each trial due to the wick inside it burning, and the heat from this chemical reaction caused the water to increase in both trials, as well, due to the transfer of exothermic heat from the flame to the water filled beaker. The experiment achieved the purpose of the lab due to the fact the candle burned, which is a chemical reaction, and heated the water from room temperature to a greater degree.
Term 2
Chapter 1: Matter and
Change
Objectives:
Chapter 2: Measurement
Objectives:
Massachusetts Curriculum Frameworks covered:
1.1 Identify and explain physical properties (such as density, melting point, boiling point, conductivity, and malleability) and chemical properties (such as the ability to form new substances). Distinguish between chemical and physical changes.
1.2 Explain the difference between pure substances (elements and compounds) and mixtures. Differentiate between heterogeneous and homogeneous mixtures.
1.3 Describe the three normal states of matter (solid, liquid, gas) in terms of energy, particle motion, and phase transitions.
6.3 Using the kinetic molecular theory, describe and contrast the properties of gases, liquids, and solids. Explain, at the molecular level, the behavior of matter as it undergoes phase transitions.
Objectives:
- Define chemistry.
- Chemistry is the study of the composition,
structure, and properties of matter, the processes that matter undergoes, and
the energy changes that accompany these processes.
- Distinguish between the physical properties and
chemical properties of matter.
- Physical Properties: characteristics that can be
measured or observed without changing the identity of the substance
- Chemical Properties: the ability of a substance to
undergo a chance that transforms into another substance
- Classify changes of matter as physical or chemical.
- Explain the gas, liquid, and solid states in terms
of particles.
- Explain how the law of conservation of energy
applies to changes of matter.
- matter cannot be created or destroyed, the poducts
formed must consist of the atoms which form the reactants. This simply means
that chemical equations must be "balanced" so that there is any equal
amount of atoms on either side of the equation
- Distinguish between a mixture and a pure substance.
Chapter 2: Measurement
Objectives:
- Distinguish between qualitative and quantitative observations.
- Quantitative:
a quantity that has magnitude size or aount. (mass, volume, density)
- Qualitative: relating
to, measuring, or measured by the quality of something rather than its
quantity.
2. Distinguish between a quantity, a unit, and a measurement standard.
3. Name and use SI units for length, mass, time, volume, and density.
4. Distinguish between mass and weight.
- Mass is the
amount of matter in an object
- Weight is the
amount of gravity pulling down on an object
5. Perform density calculations.
6. Transform a statement of equality into a conversion factor. (level 1 only)
7. Distinguish between accuracy and precision.
8. Determine the number of significant figures in measurements.
9. Perform mathematical operations involving significant figures.
10. Convert measurements into scientific notation.
Massachusetts Curriculum Frameworks covered:
1.1 Identify and explain physical properties (such as density, melting point, boiling point, conductivity, and malleability) and chemical properties (such as the ability to form new substances). Distinguish between chemical and physical changes.
1.2 Explain the difference between pure substances (elements and compounds) and mixtures. Differentiate between heterogeneous and homogeneous mixtures.
1.3 Describe the three normal states of matter (solid, liquid, gas) in terms of energy, particle motion, and phase transitions.
6.3 Using the kinetic molecular theory, describe and contrast the properties of gases, liquids, and solids. Explain, at the molecular level, the behavior of matter as it undergoes phase transitions.
- Measure
with accuracy and precision (length, volume, mass, temperature, time, etc.)
- Convert
within a unit (such as, centimeters to meters).
- Use common prefixes such as milli-, centi-, and
kilo-.
- Use scientific notation, where appropriate.
- Use ratio and proportion in the solution of
problems.
- Determine the correct number of significant
figures.
- Determine percent error from experimental and
accepted values.
- Use appropriate metric/standard international
(SI) units of measurement for mass (kg); length (m); and time (s).
Benchmark Study guide
Term
4 Benchmark
Unit 8
Mole ratio- a conversion factor that relates the amounts in moles of any two substances involved in a chemical reaction
Limiting reactant- the reactant that limits the amount of the other reactant that can combine and the amount of product that can form in a chemical reaction
Excess reactant- the substance that is not used up completely in a reaction
Theoretical yield- the maximum amount of product that can be produced from a given amount of reactant
Actual yield- the measured amount of a product obtained from a reaction
Unit 9
Kinetic-Molecular Theory of Gases
Unit 8
Mole ratio- a conversion factor that relates the amounts in moles of any two substances involved in a chemical reaction
Limiting reactant- the reactant that limits the amount of the other reactant that can combine and the amount of product that can form in a chemical reaction
Excess reactant- the substance that is not used up completely in a reaction
Theoretical yield- the maximum amount of product that can be produced from a given amount of reactant
Actual yield- the measured amount of a product obtained from a reaction
Unit 9
Kinetic-Molecular Theory of Gases
- Gases consist of large numbers of tiny particles that are far apart
relative to their size.
- Collisions between gas particles and between particles and container walls
are elastic collisions (there is no net loss of total kinetic energy).
- Gas particles are continuous, rapid, random
motion. They therefore possess kinetic energy, which is energy of motion.
- There are no forces of attraction between
gas particles.
- The temperature of a gas depends on the average kinetic energy of the
particles of the gas.
Properties of gases
- Expansion- gases do not have a definite shape or volume
- Fluidity- gas particles easily slide past one another
- Low density- 1/1000 the density of the same substance in a liquid or solid state
- Compressibility- gas particles are crowded together. Volume is greatly decreased
- Diffusion and Effusion- gases spread out and mix with one another, even without being mixed
- Diffusion- spontaneous mixing of the particles of two substances caused by their
random motion
- Effusion- gas particles pass through a tiny opening (small hole in a tire)
STP is a standard set by scientists for the purpose of comparisons
- Diffusion- spontaneous mixing of the particles of two substances caused by their
random motion
- Standard pressure = 1atm
- Standard temperature = 273ºK
Gas Laws
- Dalton’s Law- states that the total pressure of a gas mixture is the sum of the partial
pressure of the component gases
- Boyle’s Law- the volume of a fixed mass of gas varies inversely with the pressure at
constant temperature
- Charles’s Law- the volume of a fixed mass of a gas at constant pressure varies directly
with the Kelvin Temperature
- Gay-Lussac’s Law- the pressure of a fixed mass of gas at constant volume varies directly with
the Kelvin Temperature
- Combined Gas Law- expresses the relationship between pressure, volume and temperature of a
fixed amount of gas
- Ideal Gas Law- a hypothetical gas that perfectly fits all the assumptions of the
kinetic-molecular theory.
- Graham’s Law- the rates of effusion or diffusion of a gas at the same temperature and
pressure are inversely proportional to the square roots of their molar mass.
Term 3 & 4 final common lab
Mass of dish and glass
77.66g
Mass of dish glass and NaHCO₃
79.75g
Mass of dish, glass, and residue (NaCl) after 1st heating
79.12g
Calculations
2.09g NaHCO₃
Moles of NaHCO₃ reacted
0.024mol NaHCO₃
Mass of product, NaCl
0.63g NaCl
Moles of NaCl produced
0.011mol NaCl
Experimental mole ratio- NaCl to NaHCO₃
Theoretical mole ratio – Nacl to NaHCO₃
Percentage error of experimental mole ratio
45.8%
Balanced Reaction: HCl + NaHCO₃ -> NaCl + CO₂ + H₂0
Post-Lab Questions
2 molecules of hydrogen + 1 molecule of oxygen -> 2 molecules of water
2 moles of hydrogen + 1 mole of oxygen -> 2 moles of water
4 grams of hydrogen + 32 grams of oxygen -> 36 grams of water
77.66g
Mass of dish glass and NaHCO₃
79.75g
Mass of dish, glass, and residue (NaCl) after 1st heating
79.12g
Calculations
- 79.75g-77.66g=
2.09g NaHCO₃
- 2.09g
NaHCO₃ (1 mol/84g)= 0.024mols NaHCO₃
- 79.75g-79.12g= 0.63gNaCl
- 0.63g
NaCl (1mol/57.44g)= 0.011molsNaCl
- 0.011mol
NaCl/0.024mol NaHCO₃
- HCl
+ NaHCO₃ -> NaCl + CO₂ + H₂0
- 1mol
NaCl/1mol NaHCO₃
- 0.011mol
NaCl/0.024mol NaHCO₃ (100) = 45.8%
2.09g NaHCO₃
Moles of NaHCO₃ reacted
0.024mol NaHCO₃
Mass of product, NaCl
0.63g NaCl
Moles of NaCl produced
0.011mol NaCl
Experimental mole ratio- NaCl to NaHCO₃
Theoretical mole ratio – Nacl to NaHCO₃
Percentage error of experimental mole ratio
45.8%
Balanced Reaction: HCl + NaHCO₃ -> NaCl + CO₂ + H₂0
Post-Lab Questions
- BaCl₂
+ 2AgNO₃ -> 2AgCl
+ Ba(NO₃)₂
- 14.5g
AgCl (1mol/143.32g)= 0.1mol AgCl
10.2g BaCl₂ (1mol/208.23g)= 0.05mol BaCl₂
- Baking powder
consists of baking soda, one or more acid salts plus cornstarch to absorb any
moisture so a reaction does not take place until a liquid is added to the
batter.
-
2 molecules of hydrogen + 1 molecule of oxygen -> 2 molecules of water
2 moles of hydrogen + 1 mole of oxygen -> 2 moles of water
4 grams of hydrogen + 32 grams of oxygen -> 36 grams of water