# General

### Chat

When doing a somewhat complex chemistry problem (for me at least), do you round at the end or at each step? This is with significant figures.

Here's an example problem (if you feel like doing it):
Phoebe's insulated foam cup is filled with .150kg of coffee (S=4187 J/kg°C) that is too hot to drink, so she adds .01kg of milk (S=3800 J/(kg°C) at 5.0°C. If the coffee has an initial temperature of 70°C, how hot is the coffee after the milk is added? (What is the final temperature of the coffee and milk mixture?)
Remember: q = ms (delta) t

Also, if someone could explain Quantum chemistry in simple terms, that'd be great.

June 27, 2011

I think you'd look at the original question.

I haven't done anything on this level, so idk for sure.

June 27, 2011

[quote=ClementZ]No.

Rule of thumb: if there are decimals along the way, don't round until the very end.
Doing so may drastically change the final answer.[/quote]

June 27, 2011 - edited

No.

Rule of thumb: if there are decimals along the way, don't round until the very end.
Doing so may drastically change the final answer.

June 27, 2011 - edited

[quote=FirePainguin]This is definitely physics, equilibrium in chemistry is entirely different. To answer the significant figures question, you always do that at the end.[/quote]

how do you know how many sig figs to round to though? do you look at the entire problem and find the least amount or do you look at only the original question?

June 27, 2011 - edited

You in AP chemistry? I finished my year of chemistry and didn't learn this.

June 27, 2011 - edited

[quote=Snap4]I believe that's thermodynamics, which is physics, not chemistry. o:[/quote]

for us at least it was in both courses.

June 27, 2011 - edited