Mission Possible C

[Cheese_Muffin_Man]

Hey so for scoring wise, when you have
Mechanical to Chemical that is 30 points
if you have another Mechanical to Chemical is that 0 points or 20 points?

0

[chalker]

Although I have heard some call adding salt to water a chemical reaction, just about every chemist will call this a physical change. I wouldn't expect your supervisor to score it as chem->electric. You're safer not to use that as a transfer

Hmm. It's not so clear cut. From Wikipedia( http://en.wikipedia.org/wiki/Sodium_chloride):

"The attraction between the Na+ and Cl− ions in the solid is so strong that only highly polar solvents like water dissolve NaCl well. When dissolved in water, the sodium chloride framework disintegrates as the Na+ and Cl− ions become surrounded by the polar water molecules. These solutions consist of metal aquo complex with the formula [Na(H2O)8]+, with the Na-O distance of 250 pm. The chloride ions are also strongly solvated, each being surrounded by an average of 6 molecules of water.[4] Solutions of sodium chloride have very different properties from pure water."

Now there is indeed debate over whether this is a 'physical' or 'chemical' reaction (just do a google search for 'Is dissolving salt in water a chemical or physical reaction'). In fact, Wikipedia, as usual, provides a good summary of the source of the confusion (http://en.wikipedia.org/wiki/Physical_reaction):

"Many chemical changes are irreversible, and many physical changes are reversible, but reversibility is not a certain criterion for classification. Although chemical changes may be recognized by an indication such as odor, color change, or production of a gas, every one of these indicators can result from physical change"

However, looking at the rules closely, note they don't say the words 'chemical reaction' anywhere. They refer to 'the 5 basic energy forms', which infers that all possible tasks can be classified as one of the five. Thus in my opinion (which is unofficial as always) if someone doesn't want to classify salt into water as allowable for the chemical energy form, they need to make a strong argument as to which of the other forms it should be classified as instead.

[aahs_so]

Second to what chalker said. Dissolving salt in water breaks the ionic bonds in the solid. You get something quite different than just salty water. Many substances will dissolve in water and not change form. Salt breaks down into Na+ and Cl-. Should count. We are using it at state this week, but beauty is in the eye of the event supervisor.

An interesting thing we found and didn't expect. We are using distilled water with some copper electrodes. We didn't expect there to be any current flowing until we added the salt, but there was. After sampling several different jugs of distilled water (all in plastic) we found that most showed about 20K ohms of resistance, not the infinite we thought it would. We had to adjust our next action some to account for this. Good thing we can use other electric components now.

[chalker]

An interesting thing we found and didn't expect. We are using distilled water with some copper electrodes. We didn't expect there to be any current flowing until we added the salt, but there was. After sampling several different jugs of distilled water (all in plastic) we found that most showed about 20K ohms of resistance, not the infinite we thought it would. We had to adjust our next action some to account for this. Good thing we can use other electric components now.

Yep.. even pure water (which distilled water from the store is NOT) can conduct some electricity. See http://en.wikipedia.org/wiki/DI_water

"Electrical conductivity of ultra-pure water is 5.5 × 10−6 S·m−1 (18 MΩ cm in the reciprocal terms of Electrical Resistivity) and is due only to H+ and OH- ions produced in the water dissociation equilibrium.[8][9] This low conductivity is only achieved, however, in the presence of dissolved monatomic gases. Completely de-gassed ultra-pure water has conductivity of 1.2 × 10−4 S·m−1, whereas upon equilibration to the atmosphere it is 7.5 × 10−5 S·m−1 due to dissolved CO2 in it.[8] The highest grades of ultrapure water should not be stored in glass or plastic containers because these container materials leach (release) contaminants at very low concentrations. Storage vessels made of silica are used for less demanding applications and vessels of ultrapure tin are used for the highest purity applications. It is worth noting that although electrical conductivity only indicates the presence of ions, the majority of common contaminants found naturally in water ionize to some degree. This ionization is a good measure of the efficacy of a filtration system, and more expensive systems incorporate conductivity-based alarms to indicate when filters should be refreshed or replaced. For comparison, .[10] sea water has a conductivity of perhaps 5S/m (53 mS/cm is quoted), while normal un-purified tap water may have conductivity of 5mS/m(50uS/cm) (to within an order of magnitude), which is still some 2 or 3 orders of magnitude higher than the output from a well functioning demineralizing or distillation mechanism, so low levels of contamination or declining performance are easily detected."

[JTMess]

How large are your missions right now?

We are working on dremeling down the sides of ours from about 32x32x32cm, although we don't really see how one or two of the dimensions can get smaller than 30cm if you're attempting the sorting bonus task (our pint containers themselves are 12cm tall and have an almost 10cm diameter). We weren't even able to incorporate all the energy transfer tasks into our 32x32x32 device along with the pint containers.

[Miguelm15]

Can some one help me I have two things I am not clear about.
1) can we glue magnets in one of our 1 pint container and still have it a "legal" contaner to get bonus points?
2) if it is legal to add magnets then is it legal to cut holes out of the bottom of the 1 pint contaner to allow unwanted things to flow fhrough?

[wlsguy]

Can some one help me I have two things I am not clear about.
1) can we glue magnets in one of our 1 pint container and still have it a "legal" contaner to get bonus points?
2) if it is legal to add magnets then is it legal to cut holes out of the bottom of the 1 pint contaner to allow unwanted things to flow fhrough?

They already issued an FAQ on this. http://www.soinc.org/node/1332
In short, yes and yes as long as the container can still hold the objects within its volume.

[aahs_so]

Well....our high school team really messed up and won state. I was counting on not having to work with these MP rules after this weekend. The kids are excited and one of them wanted to start improving our machine today (day after the competition, we got MP gold). I told him to think about the improvements he wanted to make, but we wouldn't start work until later this week. Anyway, on to nationals.

[Robotica]

Well....our high school team really messed up and won state. I was counting on not having to work with these MP rules after this weekend. The kids are excited and one of them wanted to start improving our machine today (day after the competition, we got MP gold). I told him to think about the improvements he wanted to make, but we wouldn't start work until later this week. Anyway, on to nationals.

Congratulations! I took a quick look at the NM results for the tournament, how does your state calculate team scoring? It has the 1st place team listed with 403 pts. and the 5th place team with 272 pts.?

[aahs_so]

Well....our high school team really messed up and won state. I was counting on not having to work with these MP rules after this weekend. The kids are excited and one of them wanted to start improving our machine today (day after the competition, we got MP gold). I told him to think about the improvements he wanted to make, but we wouldn't start work until later this week. Anyway, on to nationals.

Congratulations! I took a quick look at the NM results for the tournament, how does your state calculate team scoring? It has the 1st place team listed with 403 pts. and the 5th place team with 272 pts.?

Our state uses the opposite scoring system from nationals. They award 20 pts for 1st, 19 for 2nd, 18 for 3rd, etc. There are a 25 teams at state in each of the B and C divisions.