Is this equation correct?

[Pretty in Pink]

My chemistry professor gave the class the following equation and asked us to isolate ∆T:

 

(SH) = q/(m) x (∆T)

 

The way the equation was written (it was typed just like this, horizontally, exactly as I have typed it here), I could not tell whether he meant:

 

SH = (q/m)(∆T), or

 

SH = q/[m(∆T)].

 

After class I told him that I found the given equation confusing, and asked him why there were no brackets to show that ∆T was included in the denominator of the fraction.

 

He said they were not necessary, and then asked me if I had taken college algebra yet...? I did, actually, and earned a high A last semester.

 

I have no idea why he put parenthesis around SH in the original equation either?

 

So, what am I missing here? The denominator needs brackets, no? If not, can someone explain why?

[Nakia]

You lost me with the first sentence. I came very close to failing high school chemistry. Sorry I can't be more helpful, but I'm sure some of the brilliant WTMers can help you!

 

BTW, what are you going to school for?

[Greta]

:confused:

 

Without brackets, you just do the operations in order from left to right, right? So I would have interpreted it the same way you did. So, someone correct me if I'm wrong, but he did NOT need brackets around SH or around *individual* terms like m, he DID need brackets around the entire denominator, so maybe he's the one who needs to take a college algebra class????

[kiana]

You're right, it should be in the numerator, given standard order of operations.

[Pretty in Pink]

BTW, what are you going to school for?

 

Nakia, I am applying to the nursing program at the end of this semester. My ultimate goal is probably CNM.

Edited August 18, 2010 by Pretty in Pink
typo

[regentrude]

you probably mean the equation for SH being specific heat?

 

Since the amount of heat, Q, can be found from:

Q= m c deltaT (with c commonly used as symbol for the specific heat),

you would solve for the temperature difference:

 

delta T= Q/(m* specific heat)

 

If stuff like this happens again, I suggest that you try to do a dimensional analysis to see which version of the equation is correct: if you put the units for all the quantities in, the units on the left and right side of the equation must be the same.

specific heat is Joule per kilogram and per degree,

so J/(kg oC) must equal J/(kg oC) on the right hand side which tells you that delta T was in the denominator in your original equation

[Penelope]

I think the brackets around SH are to show that SH is one quantity. Not S times H.

 

The equation isn't 100% clear to me, but I would have assumed correctly.

I don't think he needed the x in the denominator, though, he could have just written q/(m)(delta T).

[Nakia]

Nakia, I am applying to the nursing program at the end of this semester. My ultimate goal is probably CNM.

 

Good for you! I am a nurse, but I only have an ADN. Chemistry is exactly what stops me from getting my BSN. :(

[Greta]

I think the brackets around SH are to show that SH is one quantity. Not S times H.

 

Yes, of course, specific heat. I wasn't thinking about what the equation was *about*. :lol: Sorry!

[Ali in OR]

Agreeing that he needed to bracket the denominator if delta T was supposed to be in the denominator. As he wrote it, you would divide q/m and then multiply by delta T. And his comment was pretty snotty, not to mention just wrong.

[Pretty in Pink]

This was our first day of Chem 1, so none of us knew what the equation stood for when he gave it to us. He just gave us a page of formulas and asked us to isolate variables to demonstrate our grasp of mathematic operations.

 

Thanks for all of the responses. And yes, SH was specific heat, so the parenthesis does make sense there, (SH).