## Density Lab B

arv101
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### Re: Density Lab B

How are you guys gonna practice the lab section?
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Killboe
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### Re: Density Lab B

arv101 wrote:How are you guys gonna practice the lab section?

No clue.
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John Richardsim
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### Re: Density Lab B

I don't exactly understand why they removed calculations of molarity from 3.d.ii. At first I thought that it was to avoid moles, but they left the ideal gas law in 3.d.iii, so I don't really know.

Another thing about the rules I don't understand is why they limit the use of parts-per notation to million and billion. For example, if I wanted to make a question about something at a concentration of 5 parts-per-trillion, couldn't I just say a concentration of 0.005 parts-per-billion in order to get around this?
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Killboe
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### Re: Density Lab B

John Richardsim wrote:I don't exactly understand why they removed calculations of molarity from 3.d.ii. At first I thought that it was to avoid moles, but they left the ideal gas law in 3.d.iii, so I don't really know.

Another thing about the rules I don't understand is why they limit the use of parts-per notation to million and billion. For example, if I wanted to make a question about something at a concentration of 5 parts-per-trillion, couldn't I just say a concentration of 0.005 parts-per-billion in order to get around this?
'

I like how I spent like an hour studying how to calculate molarity and stuff like that and then I just see this comment. kmn

Since it's a brand new event I'm assuming they're making adjustments? The event rules are very vague and not very well made. Maybe they're making the event easier? Idk
Last edited by Killboe on September 17th, 2018, 5:03 pm, edited 1 time in total.
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### Re: Density Lab B

Killboe wrote:
John Richardsim wrote:I don't exactly understand why they removed calculations of molarity from 3.d.ii. At first I thought that it was to avoid moles, but they left the ideal gas law in 3.d.iii, so I don't really know.

Another thing about the rules I don't understand is why they limit the use of parts-per notation to million and billion. For example, if I wanted to make a question about something at a concentration of 5 parts-per-trillion, couldn't I just say a concentration of 0.005 parts-per-billion in order to get around this?
'

I like how I spent like an hour studying how to calculate molarity and stuff like that and then I just see this comment. kmn
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### Re: Density Lab B

Unome wrote:
Killboe wrote:
John Richardsim wrote:I don't exactly understand why they removed calculations of molarity from 3.d.ii. At first I thought that it was to avoid moles, but they left the ideal gas law in 3.d.iii, so I don't really know.

Another thing about the rules I don't understand is why they limit the use of parts-per notation to million and billion. For example, if I wanted to make a question about something at a concentration of 5 parts-per-trillion, couldn't I just say a concentration of 0.005 parts-per-billion in order to get around this?
'

I like how I spent like an hour studying how to calculate molarity and stuff like that and then I just see this comment. kmn
It's an extremely useful thing to know anyway if you're ever going to do any chem events or take any chem classes in the future.

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### Re: Density Lab B

Any of you know how to solve the number density of the green skittles in a bag thing?
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### Re: Density Lab B

I think the number density of skittles or M&Ms in a bag is kind of a weird question to ask. If the volume is just in units of "bags", then it's literally just counting the number of skittles/M&Ms of a certain color. If it is in units of cubic centimeters or the sorts, then there's the difficulty of being able to measure the volume of the bag, which would be able to change once the bag is opened. The only thing I can imagine for this would be dunking the bag in a beaker or large graduated cylinder to measure the volume and then opening the bag to count.

I also think having this in a test would raise certain logistical issues as well. If one bag is provided for all teams, skittles/M&Ms are bound to go missing. If a bag is provided for each team, the exact counts and measurements would vary between teams, making it pretty much impossible to evaluate teams on their accuracy.

Am I not thinking of something here?
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### Re: Density Lab B

Do any of you know if there are any practice tests for Density Lab?

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### Re: Density Lab B

someone1580 wrote:Do any of you know if there are any practice tests for Density Lab?
On the wiki if you go to the old test exchange, on the 2018 full test set for Garnet Valley Invitational, there should be a test for Density that was run as a trial last year (since its a trial test, it is fairly basic, so it would be a good place to start off with, but don't expect tests this year to be like that).
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