Keep the Heat B/Thermodynamics C

[inthewoods]

The rules define the written portion of the test to be temp conversions, definitions of heat units, thermal conductivity, heat capacity, specific heat, the laws and history of thermo, and thermo processes. How much of this is actually chemistry related and do the supervisors have the liberty to include chemistry on the test?

[harryk]

The rules define the written portion of the test to be temp conversions, definitions of heat units, thermal conductivity, heat capacity, specific heat, the laws and history of thermo, and thermo processes. How much of this is actually chemistry related and do the supervisors have the liberty to include chemistry on the test?

Thermodynamics is a subject area that includes both chemistry and physics. From the tests I've taken most of the material covered is more chemistry related, this includes mostly temp conversions and specific heat. I have seen much fewer true physics questions, though these usually cover thermodynamic processes, heat engines, and energy problems. If you nothing at all, I'd suggest starting with the chemistry side of things before moving to the physics side.

[135scioly]

The rules define the written portion of the test to be temp conversions, definitions of heat units, thermal conductivity, heat capacity, specific heat, the laws and history of thermo, and thermo processes. How much of this is actually chemistry related and do the supervisors have the liberty to include chemistry on the test?

To anyone who has taken a test at competitions, are the tests on the test exchange pretty much what is on the test? A lot of the questions on the test exchange section are a lot more difficult than I was thinking the test would be...

[Mr Sarcastic]

Is perlite allowed to be used as an insulating material?

Well, perlite is used as loose-fill thermal insulation in construction, so if I were you I would take the safe route and use something else.
If the instructor knows anything about perlite, they will probably call it a prohibited material.

[inthewoods]

We are catching on with the specific heat, temp conversions, thermal expansion etc as mentioned in previous post. How do we get out of the woods on this one:

Propane, C3H8, is a common fuel gas. Use the following to calculate the kJ of heat produced when 99.00 grams of propane react with 288.0 grams of oxygen gas.
C3H8g + 5 O2g → 3CO2g + 4H2O g deltaH = -2043kJ

Thank You!!!!

[inthewoods]

The rules define the written portion of the test to be temp conversions, definitions of heat units, thermal conductivity, heat capacity, specific heat, the laws and history of thermo, and thermo processes. How much of this is actually chemistry related and do the supervisors have the liberty to include chemistry on the test?

To anyone who has taken a test at competitions, are the tests on the test exchange pretty much what is on the test? A lot of the questions on the test exchange section are a lot more difficult than I was thinking the test would be...

We are catching on with the specific heat, temp conversions, thermal expansion etc as mentioned in previous post. How do we get out of the woods on this one:

Propane, C3H8, is a common fuel gas. Use the following to calculate the kJ of heat produced when 99.00 grams of propane react with 288.0 grams of oxygen gas.
C3H8g + 5 O2g → 3CO2g + 4H2O g deltaH = -2043kJ

Thank You!!!

[Skink]

We are catching on with the specific heat, temp conversions, thermal expansion etc as mentioned in previous post. How do we get out of the woods on this one:

Propane, C3H8, is a common fuel gas. Use the following to calculate the kJ of heat produced when 99.00 grams of propane react with 288.0 grams of oxygen gas.
C3H8g + 5 O2g → 3CO2g + 4H2O g deltaH = -2043kJ

Thank You!!!

Looks like you have to determine the limiting reactant.
First, calculate the molar masses of each reactant. 3(12.0107)+8(1.00794)=36.0321+8.06353=44.09562g/mol propane
(15.9994)2=31.9988g/mol oxygen

Now, determine which one is limiting.
99.00g propane X 1mol propane/44.09562g propane = 2.2471mol propane
288.0g oxygen X 1mol oxygen/31.9988g oxygen = 9.0003mol oxygen

They're in a 1:5 ratio, so propane looks limiting. We better check.
9.0003mol oxygen X 1mol propane/5mol oxygen = 1.8001mol propane
Nevermind. Oxygen is limiting. The oxygen only needs 1.8001 moles to react to completion, and we have more than two available.

Now, we calculate how much energy is produced.
1.8001mol oxygen X -2043kJ/1mol oxygen = -3678kJ

[emmmerz]

One thing I was seriously hoping would change was the way the actual testing of the "box" was done. There were many sources of error and that really reduced the accuracy of the measurement of the box's insulating capabilities. This was a big thing last year. Anyone else notice???

our people who tested us heated up our water in a huge fish tank and it wasnt heated up until like 15 minutes into the event. it obviously wasnt very well thought out and wasnt accurate. our team place 2nd overall at regionals (this was at regionals by the way, state was a little better but not much)

[emmmerz]

Is fiberglass allowed for heat insulation?

no that is a comercial heat insulation, its in your rules...

[inthewoods]

We are catching on with the specific heat, temp conversions, thermal expansion etc as mentioned in previous post. How do we get out of the woods on this one:

Propane, C3H8, is a common fuel gas. Use the following to calculate the kJ of heat produced when 99.00 grams of propane react with 288.0 grams of oxygen gas.
C3H8g + 5 O2g → 3CO2g + 4H2O g deltaH = -2043kJ

Thank You!!!

Looks like you have to determine the limiting reactant.
First, calculate the molar masses of each reactant. 3(12.0107)+8(1.00794)=36.0321+8.06353=44.09562g/mol propane
(15.9994)2=31.9988g/mol oxygen

Now, determine which one is limiting.
99.00g propane X 1mol propane/44.09562g propane = 2.2471mol propane
288.0g oxygen X 1mol oxygen/31.9988g oxygen = 9.0003mol oxygen

They're in a 1:5 ratio, so propane looks limiting. We better check.
9.0003mol oxygen X 1mol propane/5mol oxygen = 1.8001mol propane
Nevermind. Oxygen is limiting. The oxygen only needs 1.8001 moles to react to completion, and we have more than two available.

Now, we calculate how much energy is produced.
1.8001mol oxygen X -2043kJ/1mol oxygen = -3678kJ

Thank you!