Density Lab B

[jaah5211]

Would questions about unit cells for solid density be considered too much or difficult for Density lab event?

[splane21]

Would questions about unit cells for solid density be considered too much or difficult for Density lab event?

I think conceptually yes. This isn't a topic that is even extensively covered in high school Chemistry and I know a lot of college students who struggle to understand unit cells conceptually in my Materials Science Class. I can't imagine middle school students dealing with it.

I suppose you could give them the formula and have them plug numbers in but I'm not sure what the point of that would be. Having them plug numbers into a formula just tests their math skill.

[jaah5211]

Would questions about unit cells for solid density be considered too much or difficult for Density lab event?

I think conceptually yes. This isn't a topic that is even extensively covered in high school Chemistry and I know a lot of college students who struggle to understand unit cells conceptually in my Materials Science Class. I can't imagine middle school students dealing with it.

I suppose you could give them the formula and have them plug numbers in but I'm not sure what the point of that would be. Having them plug numbers into a formula just tests their math skill.

Good point. I was having trouble finding questions about solid density.
Since I usually study chemistry, that was the closest concept based questions that I could ask...

I was planning to include bcc and fcc. Then ask about packing efficiency and denisty, but i agree that it is too much for density lab for division B.

[jaah5211]

Would phase diagram be too much for density as well?

[AquaFlame485]

At 2019 NC states there was a lab where you calculated the density of shaving cream. You sprayed some foam on a paper towel and sucked up a given amount using a syringe and calculated that density, then compressed the syringe a given amount and calculated that density. It was pretty bad because trying to compress the syringe and measure its mass at the same time is hard. Piedmont squirted foam all over my partner, too. It was an accident though.

yo that was us i was the one with black hair

[NSCDS3RdCaptain]

Is stoichiometry allowed in Density Lab?

[NewSciolyer]

I dont' think that is necessary in Density lab. I have a question though, how is the hands-on portion of the task graded? Last invitationals my partner and I (it was the skittles one) just wrote down the answer after calculating it in our calculators. Do you have to write a step by step of how you found it? Thanks.

[knightmoves]

I dont' think that is necessary in Density lab. I have a question though, how is the hands-on portion of the task graded? Last invitationals my partner and I (it was the skittles one) just wrote down the answer after calculating it in our calculators. Do you have to write a step by step of how you found it? Thanks.

Depends on the ES. In general, I'd assume that an ES wants to see your raw data recorded (because this is science - we record the raw data) and wants to see you compute the answer preserving the correct number of sig figs. I'd also assume that on the typical question there'd be partial credit available for doing the right thing even if you made a mistake somewhere - if you just write down the answer, you give up any chance of that.

[knightmoves]

Is stoichiometry allowed in Density Lab?

Depends on what you're asking, I think. It's not on the syllabus, and in general it doesn't fall into the realm of "science middle school kids probably know", so don't go digging around in your HS Chem text for stoichiometry questions. But some stoichiometry questions are basically common sense - it doesn't take specialist knowledge to be told that hydrogen and oxygen gas react in a 2:1 ratio to make water, and to draw conclusions based on that.

[NewSciolyer]

Thanks!