I will freely admit that I am “helping” my son with his homework. He didn’t bring his Science book home, and Chemistry was never one of my strengths.
The question is “You examined a mixture of iron and sulfer. Why would you be able to reproduce this mixture with the same elements once they have been separated?”
I am clueless, and while I am Google-ing, I am not finding what I need to help the kid. Please, would someone give me a hand with this?
To restate the question: “What properties of the mixture could you measure to determine the ratio of one element to the other?” Hope that helps.
Maybe I’m missing something, but that seems like a very dodgily-worded question. But yeah, it seems to be asking how you would use the different properties of iron and sulfur to tell how much there was of each in the mixture. So you look at the properties of metals and non-metals and find a difference which you can use to separate them and measure the amounts.
Nope, just made my head hurt!
Perhaps I should add that my son is in the sixth grade and has a slight learning disability.
Myself, just not any good with Chemistry.
He said that the mixture was small black grains mixed with a yellow powder. Even I can figure out the iron is the black grains and the sulfur is the yellow powder. I asked my son if they separated the mixture with a magnet, he replied “Yes”. So, am I making this question harder than it needs to be? Can’t the mixture be reproduced by pouring the two elements together?
I hate homework. I wish I could just not give a care about my kid’s homework, but I do care. I appreciate your reply Q.E.D. but I need a more simple answer. Thanks, though.
Well, I agree, it’s an ambigously-worded question. By “the same elements” do they mean the substances you’ve just separated with the magnet or do they mean an indeterminate amount of the same elements from some other source? “Examinined” is also unclear. Do they mean you merely have visually inspected it or that you have access to various piece of equipment to measure different properties, such as mass and volume? It might also help if we knew the context of the question. What are some of the other questions being asked?
The chapter is titled Composition of Matter. He needed to read definitions in the book and complete a fill-in-the-blanks about the following:
Give an example of the following:
7. element - iron
8. homogeneous mixture - air
9. heterogeneous mixture - granite
I truly appreciate the assistance, this is a kid who really needs to feel successful.
Ok, clearly they are not dealing with measurable properties of the elements, like density or volume, so that’s right out. I suspect they want to know why you can mechanically separate the two elements and still be able to mix them back together in the same proportions as before. In which case, the answer ought to be evident.
Q.E.D. please, fight my ignorance. I am able to do a lot of things, but this isn’t one of them. Would you please help me phrase this answer for a twelve year old?
::feeling really stupid now::
Well, ask yourself this: What changes about the two elements when you separate the iron out with a magnet? Does anything change, other than the fact that they are no longer mixed?
I’m sorry to be so cryptic, but I’m trying to help you help him work out the answer without actually GIVING you the answer.
[QUOTE=kaiwik]
The question is “You examined a mixture of iron and sulfer. Why would you be able to reproduce this mixture with the same elements once they have been separated?”
QUOTE]
I try rephrasing odd-seeming questions differently. I would change the question up a little, like this:
You would be able to reproduce this mixture with the same elements because they (the elements) are … (or are not)…(see vocabulary list).
::and the light clicks on::
So, the reason why he would be able to reproduce the mixture is because neither element is changed by separating them, yes?
I think that’s the answer they are looking for, yes.
Yay!
Be sure to tell him to try to rephrase the question if he doesn’t understand it. That ususally worked for me pretty well.
Thank you so much, Q.E.D., csharpmajor, and Ca3799. I will now get him to figure it out. It helps if the teacher/parent already knows the answer, and as stated before, chemistry was never a favorite!
Again, thank you very much.
“Why would you be able to reproduce this mixture with the same elements once they have been separated?”
(I don’t really like the book’s definitions of substance or compound. Their use of “ordinary means” in defining a substance is sloppy. Do they mean tweezers, or a blowtorch. They probably weaseled on this because they haven’t introduced chemical bonds yet, but that seems an odd to teach in. Their definition of “compound” needlessly eliminates some perfectly good compounds, such as graphite (a polymer of carbon atoms) from consideration.)
Given the definitional approach from post #6, I’d bet teacher is looking for something along the lines of answer 2, above.
Oh, I guess I understood the question wrong, then. I thought it was asking how you could reproduce the mixture with the same proportions of each element.
(I don’t like the definition of mixture either. Most compounds are “made of two or more substances”.)
I would disagree that graphite is a compound. It is an allotrope of elemental carbon. It is no more a compound than diatomic oxygen is.
Well maybe I’m joining this conversation kind of late but isn’t this the classic grade school example of chemical change vs physical change (or mixture vs compound)?
I’ve tried looking around for a link but couldn’t find a really good one. Anyway, didn’t we all see this experiment sometime in our school days?
I’d say, they are looking for the usual chemical vs physical change, etc.