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The questions are sometimes weird, like comparing degrees of solubility with different reagents or putting calcium nitrate in the aqueous solution.

sciolympian wrote:powders seems easy, but i'm still nervous.

Agh! Only one day for me.. I am so nervous, and still... ready to die.

sciolyandmathcounts wrote:The questions are sometimes weird, like comparing degrees of solubility with different reagents or putting calcium nitrate in the aqueous solution.

ohh. we've only been putting simple observations in practice. well, there isn't much i can do now since the competition is Saturday.

I'll just hope for the best on Saturday and try to do better than dead last.

Oh, I also got a question about free ions, if that helps anyone.

Hey guys, I have question: If a powder is acidic and has a PH of 2, is it an observation or inference? Thanks

its an observation. saying it is a specific powder would be an inference

I usually put it
The ______ has a Ph 2.
The _______ is a strong acid

They might ask to compare acidity so it's important to put strong/weak as a modifier to acid or base.

Observation: The powder has a pH of 2.
Inference: The powder is acidic.
That's how we think of it.

2win wrote:Observation: The powder has a pH of 2.
Inference: The powder is acidic.
That's how we think of it.

technically both of those are inferences.
as your test using pH paper doesn't specifically say that it is a pH of two it just turns to a similar color of pH indication of 2

so a better observation would be
The powder turns pH paper red (pH 2) (could use a more specific color)
Inference: The powder has a pH of 2 (or one depends on shade of red)