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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: DarkLightA on November 20, 2009, 11:42:53 AM

Title: Is this right of a teacher?
Post by: DarkLightA on November 20, 2009, 11:42:53 AM
I'm doing chemistry in 8th grade for the first time ever, and my teacher doesn't know everything.. Hrm hrm..

He says:
Al + HCl ==> AlCl + H
Is it normal that teachers say this to new students in order to not confuse them? It seems a bit weird, as I spent about 2-3 hours online to develop a method of finding that it's actually:
Al2(m) + 6HCl(aq) ==> 2AlCl3(s) + 3H2(g)

Well, I guess I'm smart, but shouldn't students be taught the right thing from the start?

Kind regards,
"DLA"
Title: Re: Is this right of a teacher?
Post by: DrCMS on November 20, 2009, 11:57:55 AM
Did the your teacher write that equation or did they say "Aluminium reacts with Hydrochloric acid to give Aluminium Chloride and Hydrogen"?
Title: Re: Is this right of a teacher?
Post by: Borek on November 20, 2009, 12:42:09 PM
Al2(m)

2Al(s) if anything.
Title: Re: Is this right of a teacher?
Post by: DarkLightA on November 20, 2009, 12:44:31 PM
Did the your teacher write that equation or did they say "Aluminium reacts with Hydrochloric acid to give Aluminium Chloride and Hydrogen"?

My teacher has taught us to do it that way, in written form. I once asked why it said Ca + 2HCl ==> CaCl2 + H2 on a hand-out instead of Ca + HCl ==> CaCl + H which we'd learnt. He said "Just ignore that" and left. That's what started my interest in this, and now I think I'm into 9th grade stuff, so at least there was something positive about him  ::)

---

@Borek: of course, I slipped with thinking (m) for metal =)
Is it Al2 of 2Al?
Title: Re: Is this right of a teacher?
Post by: nj_bartel on November 20, 2009, 12:50:23 PM
Blegh, I hope that isn't what your teacher does.  Balancing nonredox equations is not too difficult to start from the get go.
Title: Re: Is this right of a teacher?
Post by: DarkLightA on November 20, 2009, 12:54:12 PM
Blegh, I hope that isn't what your teacher does.  Balancing nonredox equations is not too difficult to start from the get go.

The problem is that he doesn't know how to do it himself...  :-\
Title: Re: Is this right of a teacher?
Post by: renge ishyo on November 20, 2009, 01:37:49 PM
A lot of times in high schools there is such a shortage of science teachers that they have teachers who do not have a degree in science teaching science (they have to take science courses as part of their credential package which supposedly "qualifies" them to teach it, but sadly this doesn't mean they did well in those courses). This seems like one such case.

To the TC, now you know how he is handling it, so do what you can to follow your textbook and online sources so that you can build an undamaged knowledge for yourself. The teacher might innocently think to himself, "well what is the difference?", and so he thinks he is making the idea simpler, but the way the teacher is teaching it ignores the concept of valence (which is why you need multiple chlorines for instance; it is to balance the +3 valence on aluminum). This is obviously something you don't want to do if you plan to go further in chemistry in the future (something the teacher might be assuming you don't want to do because perhaps he doesn't like it?).

However, a word of advice TC, on the test  give the teacher the answer that he taught you in class and don't point out his mistakes to him any longer. It is a general rule that the less someone knows about something the more apt they are to viciously defend their ignorance when challenged. If you pointed it out to him once already and he ignored you, don't point it out again. Instead just make do and pass the class. Hopefully you will get a teacher that conforms closer to the accepted standards the next time around.

EDIT: Well, in thinking about it maybe I was a bit too harsh here. We do not know the context of the class, and maybe the teacher wants to introduce some sample reactions first and then balance them at a later point? It is not the way I would do things (he could use reactions like NaOH + HCl  :rarrow: H2O + NaCl that are simple enough and are viable chemical equations at the same time), but so long as he intends to make things right eventually (one would hope) I guess it isn't overtly wrong to do it this way. The equation Al + HCl  :rarrow: AlCl + H does describe an experimental fact, it just is not considered a valid chemical equation until it is balanced. That is the only difference between the two statements. At least he isn't doing Al + HCl  :rarrow: NaOH. I mean, it could be worse...
Title: Re: Is this right of a teacher?
Post by: renge ishyo on November 20, 2009, 02:21:09 PM
I guess DarkLightA's other post on valence answered that (didn't see that first). Your teacher is forgiven I guess for the whole 3 hours of confusion he caused you  ;)
Title: Re: Is this right of a teacher?
Post by: DarkLightA on November 20, 2009, 03:20:57 PM
I guess DarkLightA's other post on valence answered that (didn't see that first). Your teacher is forgiven I guess for the whole 3 hours of confusion he caused you  ;)

What do you mean? That stuff is self-learned online :)
Title: Re: Is this right of a teacher?
Post by: renge ishyo on November 20, 2009, 03:38:39 PM
Quote
What do you mean? That stuff is self-learned online

Way to kill my temporarily restored faith in our high school education system  :'(
Title: Re: Is this right of a teacher?
Post by: DrCMS on November 20, 2009, 04:05:00 PM
Did the your teacher write that equation or did they say "Aluminium reacts with Hydrochloric acid to give Aluminium Chloride and Hydrogen"?

My teacher has taught us to do it that way, in written form. I once asked why it said Ca + 2HCl ==> CaCl2 + H2 on a hand-out instead of Ca + HCl ==> CaCl + H which we'd learnt.

If I am reading this correctly the teacher has been teaching you in written form and you have been writing it down in equation form.

So your teacher said "calcium reacts with hydrochloric acid to give calcium chloride and hydrogen"
and so you wrote that down incorrectly as "Ca + HCl  :rarrow: CaCl + H"

Later the teacher gave you a hand out saying "calcium reacts with hydrochloric acid to give calcium chloride and hydrogen"
giving the reaction correctly as "Ca + 2HCl  :rarrow: CaCl2 + H2"

If that is the case it is you that is causing the confusion by trying to be too clever and failing.
Title: Re: Is this right of a teacher?
Post by: DarkLightA on November 20, 2009, 04:13:56 PM
So your teacher said "calcium reacts with hydrochloric acid to give calcium chloride and hydrogen"
and so you wrote that down incorrectly as "Ca + HCl  :rarrow: CaCl + H"

Later the teacher gave you a hand out saying "calcium reacts with hydrochloric acid to give calcium chloride and hydrogen"
giving the reaction correctly as "Ca + 2HCl  :rarrow: CaCl2 + H2"

If that is the case it is you that is causing the confusion by trying to be too clever and failing.

No, we've been taught both word equations and symbol equations. The teacher writes it on the board like that (incorrectly), and I write it down and go on google when I come home and disprove it to myself and learn the real thing  :-\
Title: Re: Is this right of a teacher?
Post by: DarkLightA on November 20, 2009, 04:14:36 PM
Quote
What do you mean? That stuff is self-learned online

Way to kill my temporarily restored faith in our high school education system  :'(

Any time  ;)

At least the internet is good..
Title: Re: Is this right of a teacher?
Post by: DrCMS on November 20, 2009, 04:23:38 PM
So your teacher said "calcium reacts with hydrochloric acid to give calcium chloride and hydrogen"
and so you wrote that down incorrectly as "Ca + HCl  :rarrow: CaCl + H"

Later the teacher gave you a hand out saying "calcium reacts with hydrochloric acid to give calcium chloride and hydrogen"
giving the reaction correctly as "Ca + 2HCl  :rarrow: CaCl2 + H2"

If that is the case it is you that is causing the confusion by trying to be too clever and failing.

No, we've been taught both word equations and symbol equations. The teacher writes it on the board like that (incorrectly), and I write it down and go on google when I come home and disprove it to myself and learn the real thing  :-\

OK sorry, this means your teacher is crap (or you need glasses)
Title: Re: Is this right of a teacher?
Post by: renge ishyo on November 20, 2009, 04:37:16 PM
If I didn't live in California (49th out of 50 in the nation at last count in high school education!), and if I didn't see and experience how people are being taught here I wouldn't believe it.

This reminds me of the time I had a student come to me for help in Chem 101 when I worked as a tutor, and she angrily claimed that her teacher wasn't teaching them anything. So I did my usual "it is your responsibility to learn the material, show up to class every day, and listen to the lecture, yadda yadda," but then I had to bite my tongue when the student told me that "there was no lecture to listen to." Huh? It turns out what the teacher was doing was handing the students packets of problems and putting them in groups to "teach each other" as part of a new experimental "hands off" approach to teaching students. The student was almost finished with a year course in chem 101, and she didn't even know what an atom was. It was truly a sad thing to see.
Title: Re: Is this right of a teacher?
Post by: cth on November 20, 2009, 05:30:32 PM
If I didn't live in California (49th out of 50 in the nation at last count in high school education!), and if I didn't see and experience how people are being taught here I wouldn't believe it.

This reminds me of the time I had a student come to me for help in Chem 101 when I worked as a tutor, and she angrily claimed that her teacher wasn't teaching them anything. So I did my usual "it is your responsibility to learn the material, show up to class every day, and listen to the lecture, yadda yadda," but then I had to bite my tongue when the student told me that "there was no lecture to listen to." Huh? It turns out what the teacher was doing was handing the students packets of problems and putting them in groups to "teach each other" as part of a new experimental "hands off" approach to teaching students. The student was almost finished with a year course in chem 101, and she didn't even know what an atom was. It was truly a sad thing to see.

 :o I guess that was a pretty extreme case, right? I have been told California is the richest state in the US, so it should do better than that.
Title: Re: Is this right of a teacher?
Post by: Borek on November 20, 2009, 05:43:50 PM
If I didn't live in California (49th out of 50 in the nation at last count in high school education!), and if I didn't see and experience how people are being taught here I wouldn't believe it.

Long and it starts from something completely different, but if you are patient enough to read 30 posts or so you will be no longer surprised by anything:

http://mailer.uwf.edu/listserv/wa.exe?A2=ind0911&L=chemed-l&T=0&F=&S=&P=17630

(click Next in topic to advance). Note that this is an ongoing discussion that started on Wednesday.
Title: Re: Is this right of a teacher?
Post by: renge ishyo on November 20, 2009, 07:31:18 PM
Quote
I have been told California is the richest state in the US, so it should do better than that.

That's thinking like "they" do  ;) Money has nothing to do with academic performance because none of it ever gets spent to lure in more highly qualified teachers (to be fair, the problem to begin with is the tenure system over here has made it so you *can't* get rid of the bad teachers even if you wanted to).

Quote
d if I didn't see and experience how people are being taught here I wouldn't believe it.

Long and it starts from something completely different, but if you are patient enough to read 30 posts or so you will be no longer surprised by anything:

http://mailer.uwf.edu/listserv/wa.exe?A2=ind0911&L=chemed-l&T=0&F=&S=&P=17630

(click Next in topic to advance). Note that this is an ongoing discussion that started on Wednesday.

Yeah, Borek that was the sort of thing that I was alluding to earlier. Although to be honest, even a biology teacher teaching chemistry is an improvement over some of the things I have heard. For instance, I have even heard of language arts majors teaching chemistry over here! It is in this way that you end up with teachers who can't even balance a chemical equation.

The TC is just going to have to teach himself which is not really uncommon here. Much of my lower division education in college was "self taught" using over the counter books from Borders and Barnes and Nobles. That's just the way things have to be I guess.
Title: Re: Is this right of a teacher?
Post by: DrCMS on November 21, 2009, 05:11:19 AM
:o I guess that was a pretty extreme case, right? I have been told California is the richest state in the US, so it should do better than that.

The Californian economy is very large (if it was in independent country I think they say it would by the 8th largest by size of its economy/GDP) however the state is bankrupt due to the way the laws need to be approved by the population.  So they vote to spend lots and be very green but not the raise the taxes to pay for it all. 
Title: Re: Is this right of a teacher?
Post by: JGK on November 23, 2009, 12:17:08 PM
If I didn't live in California (49th out of 50 in the nation at last count in high school education!), and if I didn't see and experience how people are being taught here I wouldn't believe it.


 :o I guess that was a pretty extreme case, right? I have been told California is the richest state in the US, so it should do better than that.

California has a current budget deficit of 20.7 Billion Dollars, if they're the richest state, I'd hate to see the poorest
Title: Re: Is this right of a teacher?
Post by: 1234567188 on December 02, 2009, 11:34:06 AM
I'm doing chemistry in 8th grade for the first time ever, and my teacher doesn't know everything.. Hrm hrm..

He says:
Al + HCl ==> AlCl + H
Is it normal that teachers say this to new students in order to not confuse them? It seems a bit weird, as I spent about 2-3 hours online to develop a method of finding that it's actually:
Al2(m) + 6HCl(aq) ==> 2AlCl3(s) + 3H2(g)

Well, I guess I'm smart, but shouldn't students be taught the right thing from the start?

Kind regards,
"DLA"

Yea, It's kind of the normal thing a majority if not all of the chemistry you do in 8th grade will be dealing in concepts not specfics. So the exacts arn't really important, you will get to balancing later on.
Title: Re: Is this right of a teacher?
Post by: JGK on December 02, 2009, 12:23:34 PM
I'm doing chemistry in 8th grade for the first time ever, and my teacher doesn't know everything.. Hrm hrm..

He says:
Al + HCl ==> AlCl + H
Is it normal that teachers say this to new students in order to not confuse them? It seems a bit weird, as I spent about 2-3 hours online to develop a method of finding that it's actually:
Al2(m) + 6HCl(aq) ==> 2AlCl3(s) + 3H2(g)

Well, I guess I'm smart, but shouldn't students be taught the right thing from the start?

Kind regards,
"DLA"

Yea, It's kind of the normal thing a majority if not all of the chemistry you do in 8th grade will be dealing in concepts not specfics. So the exacts arn't really important, you will get to balancing later on.


There's a problem with that method of teaching in that some kids just can't adjust from that initial concept to the specifics when they're taught them later on. When i was a kid the local schools used ITA to teach kids to learn English initially http://en.wikipedia.org/wiki/Initial_Teaching_Alphabet (http://en.wikipedia.org/wiki/Initial_Teaching_Alphabet) (luckily my mother wasn't a fan of this "trendy" stuff and taught me to read & write before I entered the school system).  Unfortunately, a number of the kids I studied with just could not cope with the transition from one system to another and it really set them back. Probably why I can see the value in more conservative teaching styles.
Title: Re: Is this right of a teacher?
Post by: Evaldas on December 02, 2009, 01:03:42 PM
We aren't awarded with the best chemistry teacher as well (although I'm not from US), she can't handle the class (well that's not really her responsibility, but other teachers manage to do it) nor she has the interest in trying. If we have a chemistry test and someone asks a questions about the exercise FROM THE TEST the teacher is more than glad to help during the test (not sure if that's a bad quality for everyone tho :D). Or for example there was an exercise in the papers we've been given for homework which sounded something like this "4 alloyed ampoules in room temperature are filled with a) hydrogen, b) ozone c) water d) ammonia. Which ampoule has the most molecules?" so she said that she wouldn't rate this exercise, since in her opinion somebody made a mistake, because we were speaking about gases and ideal conditions and etc, and she said it's weird for the authors to create such exercise if everywhere in the book it was written that the same amount of gases in the same volume have the same number of molecules, I then explained to her that water is not a gas, and since it's room temperature water is A LIQUID and the ampoule filled with water has the most molecules, and her response was "still, doesn't make any sense. I don't know... I'm still not going to rate this exercise".
I know she's going to leave in a few months, I'm kinda glad about that, but also sad a bit, cos I've come to like her, because she's sweet no matter what.