[rosiegirl]

I completed a lab and found that when that if steel wool is placed in a container the temperature increased 5 degrees.  I would greatly appreciate any assistance with these problems, if anyone can point me in the direction of resources that would explain how to complete this assignment or walk me through an example I would be immensely grateful.




Write the balanced equation, with the enthalpy component, for the rusting process, given that Hf for iron and oxygen is 0 and Hf for ferric oxide is -826 kJ/mol.

What was the total heat change of the reaction you observed? Use the following conversion ratios and assumptions:
a. Heat (J) = Specific Heat (J / g - deg C) * Mass (g) * Change in Temperature (deg C)
b. Specific Heat of Air = 0.71 J / g - deg C
c. Mass of Air = mass of air in jar if empty – mass of air displaced by steel wool
typical jar is 1 pint or 0.000473 m3
the density of air is 1.2 kg / m3
in a 1 pint jar, a typical steel wool pad will displace 20% of the air
d. Change in Temperature as observed
deg C = (deg F - 32) * 5/9

Using the heat change you observed and the balanced equation for the reaction, calculate the mass of iron that rusted during the reaction.

[constant thinker]

Your questions will become easier once you read number 4 on this website.

[rosiegirl]

I had initially included a few lines, explaining my situation which I deleted because I believe it made my post unnecessarily lengthy. I'm taking a course online and the online textbook, my only resource has is proved insufficient in this area.  I have asked my instructor about this lab, expressed that I have read the text multiple times and need either examples/explanations/additional resources because I'm just not getting it. She said the lab had caused difficulty with all her students and was in the process of being rewritten (which seems to point to a lack of information provided in the text, but that's just me), and I should just "try." I would love to personally, but I have no idea where to begin, which is why I asked here. I did read the rules multiple times before posting, I'm sorry if I didn't make it clear that I do not want anyone to do my assignment for me. I simple want to understand what I am supposed to do. Let me rephrase my question: Where can I find material that teaches the concepts necessary to complete the above assignments? Where can I find example problems similar to this assignment so that I can attempt a few of these types of problems? If you can't help me, then you can't help me. Thanks for your time.

[Yggdrasil]

Write the balanced equation, with the enthalpy component, for the rusting process, given that Hf for iron and oxygen is 0 and Hf for ferric oxide is -826 kJ/mol.

Once you write the balanced chemical reaction for the formation of ferric oxide (i.e. iron(III) oxide), you can find the change in enthalpy for the reaction by using Hess's Law (if you do not know what this is, you should look it up in your chemistry textbook or on Wikipedia [http://en.wikipedia.org/wiki/Hess%27s_Law]).  Hint: the answer is very obvious.

What was the total heat change of the reaction you observed? Use the following conversion ratios and assumptions:
a. Heat (J) = Specific Heat (J / g - deg C) * Mass (g) * Change in Temperature (deg C)
b. Specific Heat of Air = 0.71 J / g - deg C
c. Mass of Air = mass of air in jar if empty – mass of air displaced by steel wool
typical jar is 1 pint or 0.000473 m3
the density of air is 1.2 kg / m3
in a 1 pint jar, a typical steel wool pad will displace 20% of the air
d. Change in Temperature as observed
deg C = (deg F - 32) * 5/9

Specifically, what are you having trouble with here, calculating the heat released by the oxidation of the steel wool?

Using the heat change you observed and the balanced equation for the reaction, calculate the mass of iron that rusted during the reaction.

Should be easy once you answer the first two questions.

[rosiegirl]

I think I'm doing something wrong

4Fe + 3O2->2Fe2O3 Hf-826 kj/mol.

.01611984= (.71) × (5) × (.0045408)