Mass of Burning Steel Wool

Mass of Burning Steel Wool

Observations and Conclusions

Mass of Burning Steel Wool

• Question: Does the mass of unburned steel wool increase, decrease, or stay the same when the steel wool is burned? 

• In this experiment, we took the mass of a ball of steel wool before and after it was burnt for 3 mins!

Mass of Burning Steel Wool Experiment

During the video, pay attention to the mass. How does the mass change as the steel wool is burning?

Multiple Choice

How does the mass of the steel wool change as it is being burned?

• The mass readings on the balance increase.

• The mass readings on the balance decrease.

• The mass readings on the balance do not change.

• None of the above.

Burning Steel Wool - Video

In the burning steel wool video, we observe the mass increasing as the steel wool is burning.

Law of Conservation of Mass

• According to the Law of Conservation of Mass, mass cannot be created or destroyed.

• Let's review: What does a positive, negative, or zero mass change mean about the particles in the system?

Multiple Choice

A positive mass change means:

• Matter has entered the system.

• Matter has left the system.

• Matter has not changed within the system.

Multiple Choice

A negative mass change means:

• Matter has entered the system.

• Matter has left the system.

• Matter has not changed within the system.

Multiple Choice

A zero (0.00 g) mass change means:

• Matter has entered the system.

• Matter has left the system.

• Matter has not changed within the system.

Data Collection

Here is our data from yesterday's lab. Looking at the data, were our mass changes positive, negative, or zero?

Multiple Choice

Mass changes for our data were:

• Positive

• Negative

• Zero

Mass Changes for Mass of Burning Steel Wool

In this experiment, we observed a positive mass change! What does this mean?

Multiple Choice

In our experiment, what is the meaning of a positive mass change?

• Particles have entered the system.

• Particles have left the system.

• Particles have not entered or left the system.

Positive Mass Change?

• In this experiment, we observed a positive mass change. This means that particles entered our system during/after the burning!

• Does this positive mass change make sense in respect to our in class observations? Why or why not?

Observations:

Before burning, the steel wool started out as a metallic grey color with a wire-like texture. As the steel wool was burning, small embers appeared to fall off the steel wool ball and the ball expanded. After the steel wool was burned for 3 minutes, the color had changed to a dark grey that was no longer metallic looking. In addition, the texture had changed from “wire-like” to feeling more soft or “hay-like”. Ms. Hyland conducted an experiment where the steel wool was burned for 5 minutes. Those steel wool balls felt like they had hardened and were less flexible. 

Open Ended

Based on our observations, would we expect the mass change to be positive? Why or why not? EXPLAIN!

Observations:

Before burning, the steel wool started out as a metallic grey color with a wire-like texture. As the steel wool was burning, small embers appeared to fall off the steel wool ball and the ball expanded. After the steel wool was burned for 3 minutes, the color had changed to a dark grey that was no longer metallic looking. In addition, the texture had changed from “wire-like” to feeling more soft or “hay-like”. Ms. Hyland conducted an experiment where the steel wool was burned for 5 minutes. Those steel wool balls felt like they had hardened and were less flexible. 

Mathematical Analysis

• The average mass change for the Semester #1 data is 0.29 g

• The average mass change ALL data (our data and Semester #1 data) is 0.25 g

Mathematical Analysis

• As we can see in the average mass change, even though we would not expect the mass change to be positive, it is for both our data and the semester one data...

• BUT WHY?

Burning Steel Wool - Chemical or Physical Reaction?

In the video, listen closely to the experimenter. What is happening to the steel wool as it is burning? Is this a chemical or physical reaction?

Open Ended

Burning Steel Wool - Chemical or Physical Reaction?

Chemical Reaction

Iron to Iron Oxide! In the video, the experimenter explains the importance of "fluffing up" the steel wool so oxygen can reach the iron in the steel wool. As the steel wool burns, oxygen from the air chemically combines with the iron in the steel wool forming iron oxide.

Important things to note:

• This Lab is an example of a Chemical change. Oxygen from the air is combining chemically with the Iron in the steel wool.

• The system in the Lab is an open system. Air must be able to move into the system to keep the burning reaction going

Open Ended

Overall, on average the mass change for this lab was positive. Why do you believe we observed a positive mass change? Provide evidence :)

Why did we observe a positive mass change?

In this experiment, on average, we observed a positive mass change. A positive mass change means that particles/matter entered our system during the lab. During this lab, oxygen gas became chemically combined with the iron in the steel wool forming Iron Oxide. Since the oxygen was not chemically combined to the steel wool in our system until after the burning occured, we saw the mass increase since the oxygen particles entered the system.

Open Ended

Was mass created or destroyed or neither? Explain.

Mass created, destroyed, or neither?

Mass was neither created or destroyed during this experiment. As stated by the law of conservation of mass, matter/ mass cannot be created or destroyed. The positive mass change was due to oxygen particles entering our system during the chemical change.

Open Ended

Describe the motion of the air particles in the surroundings and the iron particles in our steel wool: Does one type or particle enter or leave our system? Explain!

Movement of Particles

During this lab, particles from the surroundings (oxygen particles) entered our system during the burning chemical change. These oxygen particles chemically combined with the iron in the steel wool. Therefore, as those particles entered the system, we saw the mass increase!