Well, I understand q = mc∆T, along with q = mH(adsbygoogle = window.adsbygoogle || []).push({}); _{v}and q = mH_{f}

What I don't understand is this graph:

http://dinosaurtheory.com/phase_change.jpg

Well, I mean, I understand THAT graph.

Here's what I don't understand:

Today in chemistry, we received a very similar graph, but the X-axis was labeled "time" instead of "added heat" as it is in the one I linked to.

I raised my hand and pointed out that the independent variable should not be "time" because nowhere in our equations were we even given "time" as a variable! "Time" actually has nothing to do with temperature. I could leave an ice cube on my table and it won't necessarily melt, then vaporize. Or, alternatively, I could throw it into the sun and it would vaporize very quickly. Also, over time I could have water vapor condense into water, then freeze into ice.

The way I see it, "time" has no right to be and independent variable on such a graph.

My chemistry teacher told me that "time" is often an independent variable in graphs, and that energy had to be calculated (meaning that added energy could not be the independent variable if we had to calculate it after the fact). But I could not get over the fact that nowhere in any equation was "time" mentioned, and I couldn't get over that.

My Question: Is time supposed to be the independent variable on this graph? Or is my thought process right in that the X-axis should be labeled "added energy?"

(I understand that time can be the X-axis with the given condition that we're heating something up over time, such that heat = constant x time, but nowhere were we given such a condition.)

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# I don't understand q = mc delta T

**Physics Forums | Science Articles, Homework Help, Discussion**