Can't Judge a Powder B

[karatekid44]

This is my first time on this event and my group is just as clueless.
we're going to start by testing some crime powders with stuff like:
mass
color
luster
coarse/fine
size/shape (shape...maybe that would only apply to crystalline stuff?)
solubility with water and HCI
pH
reactions with water
reactions with HCI
reactions with iodine (should we?)
density compared to water/HCI
benedicts? (not sure about using indicators ... bromothymol blue? methyl red? biuret solution?)
uhh i'm pretty sure we're missing a lot, so suggestions are more than welcome
thanks~

Yeah, this would be a great even for Science Crimebusters, the problem is im the only lan guy on my team so i have to interes the sixth graders.
Even if its negative. its still an observation
Magnetism
Conductivity
Are some you can do

[ddudealex1]

Yeah, I need some help with this event to. Any suggestions?

[robotman09]

Start by the magical joys of The Wiki thry the powerpoint the rest of the wiki needs work

also try the old thread

but it is really hard to help without specific questions

[ddudealex1]

Any suggestions for links to prepare for this event?

[robotman09]

i really suggest that you get practice observations and know what Quantitative and Qualitative observations also understand the difference between observation and inference
Basic worksheet
soinc powerpoint
also get some of the powders on the rules and write down all that you observe about them

[haven chuck]

We were having some confusion over the observation and inference concept, and deciding what the boundary between the two would be? Could anyone help clear this up?
i.e. Would seeing that the powder is soluble be enough to allow you to write that the powder is hydrophillic, and would that be an observation or inference?

[AlphaTauri]

I'm not really sure how to explain it other than an observation is anything that can be directly observed by, um, observing the substance, while an inference is based on an observation and prior knowledge.The clearest example I can find is from th rules:

For instance, if a student observes that when 0.1g of the powder s put into 5ml of water, the powder floats on the water until it is stirred...would receive 5 points. If a student writes an inference instead of an observation, such as the density of the substance is less than water...would receive at most 3 points.

Hope I helped.

[SOninja]

1) the powder is hydrophillic - definitely an inference
2) 0.1 g of the powder dissolved in 5 mL of water - observation
3) this powder is soluble - dunno if it is observation or inference... i'm leaning towards observation though...

[amerikestrel]

1) the powder is hydrophillic - definitely an inference
2) 0.1 g of the powder dissolved in 5 mL of water - observation
3) this powder is soluble - dunno if it is observation or inference... i'm leaning towards observation though...

I think #3 would be an inference, not an observation.

[AlphaTauri]

I'm leaning towards inference. I think the observation would be "it dissolved" and from that, you could infer that it's soluble in water, since you need the observation "it dissolved" to draw the conclusion that it's soluble.

A close example would be when you have an object in a box, you shake the box, and hear the object rattling around inside.
Observation: When you shake the box, the object rattles around inside.
Inference: The object is solid. (It's an inference 'cause you can't directly observe that the object is solid.)

[freakofnature17]

I'm leaning towards inference. I think the observation would be "it dissolved" and from that, you could infer that it's soluble in water, since you need the observation "it dissolved" to draw the conclusion that it's soluble.

A close example would be when you have an object in a box, you shake the box, and hear the object rattling around inside.
Observation: When you shake the box, the object rattles around inside.
Inference: The object is solid. (It's an inference 'cause you can't directly observe that the object is solid.)

This is right. Saying that the powder is soluble is an inference and will cost you to recieve at most like 2 or 3 (I'm not sure) points. But if you say the powder dissolved in water and one of the questions said, "Is the powder soluble in water?" you can say it is and use the observation you made to get the full 5 points.

[chill]

when we take the ph of the substance, writing the ph down in our observations would be okay or would that be considered an inference???

[robotman09]

I think if you wrote "thesubstance turned the ph paper green" that would be your observation and than you could infer the ph off of that observation

[freakofnature17]

I think if you wrote "thesubstance turned the ph paper green" that would be your observation and than you could infer the ph off of that observation

Or could say the pH of the powder is 1/2/3/4/etc. but not say whether it is a base or acid because that would be an inference. Then if one of the questions asked if the powder was a base or acid, you could use the pH to answer that and use that observation as your reason.

So basically what I'm asking is are you only allowed to say the color of the pH paper in the observations or can you say the actual pH without losing points?

[EASTstroudsburg13]

I think you should put the pH number in inferences because the paper turns a certain color and you have to compare it with the key to figure out what its pH is. Then the base vs. acid topic would be a further inference that you can put down.