GCSE question

[studiot]

 

@Studiot: Relatively new idea? I done my GCSE's back in the 1980's - we were the first to do them. The idea of writing out a 'word' equation rather than a balanced chemical equation is something I remember as being pretty standard. How is it new?

 

 

Since I didn't have the luxury of those ridiculous exams that are at the root of all today's educational evils, I don't doubt you.

 

Perhaps the idea came in with the GCSE?

[StringJunky]

 

Since I didn't have the luxury of those ridiculous exams that are at the root of all today's educational evils, I don't doubt you.

 

Perhaps the idea came in with the GCSE?

It could have been used in CSE. I did GCE and CSE.

[hypervalent_iodine]

Giving equations in written form is standard way of presenting a question; I doubt it's a new thing for the GCSE. I myself frequently encountered it throughout high school and again in undergrad. Communicating reactions verbally or through text requires that you know how to interpret these sorts of things on a regular basis, so it's understandable that students studying chemistry be tested on it.

 

I know, I know. I was just going along with your apparent interpretation that to specify only one hydrogen atom it likely say only 'one hydrogen atom'.

It appears I can't win. If I suggest one view (mine) it is countered. And then if I acquiesce to what appears to be the contrary view, I'm told I'm still wrong!

When I said "Okay, 'hydrogen' actually means either two hydrogen atoms or one hydrogen molecule." I was tempted to say 'any number from two to eternity'. But I didn't want to introduce another factor to confuse things and be shot down again on such complication!

I think the disagreement with your posts stems from the fact that you didn't seem to be grasping that the words, 'hydrogen,' and, 'oxygen,' say nothing regarding quantities; they simply refer to (in this case) the elemental forms of the two gases. This is in much the same way that magnesium chloride refers to MgCl₂ and iodine, I₂.You keep bringing numbers into it, when you shouldn't be. They are not relevant here.

A chemistry student should be able to easily glean from this that the question was talking about a reaction between H₂ and O₂, since these are the elemental forms. From this they should identify that it is a combustion reaction and lacking any source of carbon, the only product must be water.

This was a chemistry paper not a general knowledge paper. Yes, it uses 'word' in the question, but that meant nothing particular to me because what else would one use to identify what the formula referred to? Perhaps I should prefix this reply by saying 'this is a word reply' - clearly ludicrous, which was my puzzlement with 'word' in the question.

You more commonly see reactions given using chemical symbols or structures. For example:

 

(1) 2H₂ + O₂ --> 2H₂O

 

Or:

 

(2)

 

(http://www.chemgapedia.de/vsengine/vlu/vsc/en/ch/12/oc/vlu_organik/radikale/halogenierung_alkane.vlu/Page/vsc/en/ch/12/oc/radikale/radi_brom_benzyl/radi_brom_benzyl.vscml.html)

 

The reaction given in (1) is of the sort where specific ratios and balancing is important. For my area of chemistry I tend to prefer structures, as in (2), since it conveys a lot of information very succinctly.

 

A worded equation requires that you first interpret the words into actual chemical formulae and if required, that you then predict the products and balance the equation to give something similar to (1). Balancing is not required if all you need to do is predict the product(s). Keep in mind also that the words we use to describe chemical structures are not arbitrary - they follow specific syntax and are written to give exactly as much information as you need to know what the substance is. If you know how to interpret them, anyway. I suppose that is not something you were familiar with, which may have been the source of your confusion at the question.

[studiot]

 

Giving equations in written form is standard way of presenting a question; I doubt it's a new thing for the GCSE.

 

With the greatest respect, do you have any (first hand) experience of the exams that preceeded GCSE?

 

I do and I can remember taking GCE Chemistry.

I can also remember our chemistry teacher (we called her Granny) harping on about accuracy and stochiometry.

I'm pretty sure that stating the reaction as a word equation would have resulted in failure at GCE.

 

But then I can remember a time before the "No one can fail an exam" doctrine became de rigeur.

 

Looking up some questions here are two from, not a full Chemistry paper, but just the GCE General Science paper from the 1950s

 

Yes, they used the phrase "word equations" thusly

 

"Write a word equation to illustrate the process of fermentation by yeast."

 

For a chemical equation they asked

 

"CaO + H₂O = ............................"

Edited June 3, 2015 by studiot

[DrP]

Wasn't bought in for GCSE.. always been that way - it's standard.

 

 

EDIT: Even if it was then that was over 30 years ago anyway.

Edited June 3, 2015 by DrP

[hypervalent_iodine]

With the greatest respect, do you have any (first hand) experience of the exams that preceeded GCSE?

 

I do and I can remember taking GCE Chemistry

 

I've not taken it, but I've first hand experience in teaching students who have and in teaching high school / undergraduate students here. As well, another in this thread says they remember otherwise.

 

In any case, I said I doubted it, not that I knew for sure. It would seem odd to me not to test students on their ability to interpret names into chemical formula, etc., at that level, hence my doubt that it is new to this exam.

 

 

I can also remember our chemistry teacher (we called her Granny) harping on about accuracy and stochiometry.

I'm pretty sure that stating the reaction as a word equation would have resulted in failure at GCE.

 

Well sure, but the context of the brand of question you are describing is rather different. It is not asking for the same thing, so it's hardly surprising that you'd be marked wrong for answering it, well, wrongly.

 

 

Edit: it's worth adding that in the type of question you describe, you may as part of that need to convert a chemical name into a formula or structure of some kind. This is really what I'm talking about rather than questions that explicitly ask for worded answers or the like. I just mean questions that in some way test a students ability to decipher these names. Whether that forms the entire question or just part of the working out process doesn't matter.

[studiot]

 

Edit: it's worth adding that in the type of question you describe, you may as part of that need to convert a chemical name into a formula or structure of some kind. This is really what I'm talking about rather than questions that explicitly ask for worded answers or the like. I just mean questions that in some way test a students ability to decipher these names. Whether that forms the entire question or just part of the working out process doesn't matter.

 

 

 

I don't follow.

 

Of course a pupil had to be able to decipher chemical names and show some understanding of the chemicals themselves, even in the context of chemical reactions.

 

For example

 

"Underline three substances that dissolve in dilute sulphuric acid from Copper, Chalk, Zinc, Iron, Copper Sulphate, Zinc Oxide."

 

But this was not about a word equation.

 

The closest I can come is

 

Acid plus Base = Salt plus Water

 

Remembering also that I only have access to some much more general General Science papers, not the more specific Chemistry ones.

 

 

 

EDIT: Even if it was then that was over 30 years ago anyway.

 

 

What does that have to do with it?

[DrP]

It means that it has been standard for over 30 years.... and I reckon a lot longer.

 

When I was supply teaching a few years back I took an A-level maths paper home.... compared with a 1960's math o-level paper and they were comparable, so I agree, yes, the standards fell with the introduction of GCSE. Shame I am not 1 year older.

[hypervalent_iodine]

I don't follow.

 

Of course a pupil had to be able to decipher chemical names and show some understanding of the chemicals themselves, even in the context of chemical reactions.

 

For example

 

"Underline three substances that dissolve in dilute sulphuric acid from Copper, Chalk, Zinc, Iron, Copper Sulphate, Zinc Oxide."

 

But this was not about a word equation.

 

The closest I can come is

 

Acid plus Base = Salt plus Water

 

Remembering also that I only have access to some much more general General Science papers, not the more specific Chemistry ones.

 

 

 

 

What does that have to do with it?

I think maybe we're talking past each other a little. The misunderstanding in the OP seems to be from a lack of understanding in how to interpret chemic names, not simply that the reaction was written in worded form rather than with chemical formulae. I was speaking to that misunderstanding more generally then I suppose you were.

[Strange]

It appears I can't win. If I suggest one view (mine) it is countered. And then if I acquiesce to what appears to be the contrary view, I'm told I'm still wrong!

 

I don't see where you have "acquiesced"; you have consistently stuck to the view that the question is about specific quantities of hydrogen and oxygen. It isn't.

 

When I said "Okay, 'hydrogen' actually means either two hydrogen atoms or one hydrogen molecule."

 

But it doesn't mean that.

[Delbert]

 

I don't see where you have "acquiesced"; you have consistently stuck to the view that the question is about specific quantities of hydrogen and oxygen. It isn't.

I did say in my acquiescence about venturing the description of anything from two to eternity, that is, an unspecified amount. But presumably you didn't read that bit. So, I rescind my acquiescence.

 

In my twisted way perhaps what I'm trying to convey is even though one might be fully cognisant with the chemical oxidising process, if one expresses it differently or perhaps in slightly greater detail, it'll be considered a failure. Because as far as I can tell, that's the only difference in our view or description.

 

Anyway, I would've thought the question should be able to accept any answer as long as it's chemically correct, i.e. the appropriate number of atoms (or molecules) or just the general description of oxygen and hydrogen can join up and result in water.