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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?

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.

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...

x_SOninja_x wrote: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.

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.)

AlphaTauri wrote: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.

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???

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

robotman09 wrote: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?

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.