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Heating curve

Posted: Wed Feb 12, 2020 3:29 pm
by Althea Zhao 1B
How is the formula for enthalpy with a change in temperature along a heating curve different from the formula for enthalpy at temperature plateaus?

Re: Heating curve

Posted: Wed Feb 12, 2020 3:34 pm
by KaleenaJezycki_1I
For the sloped lines in a heating curve ( the solid, or liquid is heating up) for the straight horizontal lines the phase change is occurring. When calculating the sloped lines you use q=mCDeltaT but when you are at a phase change ( straight line), you use n*DeltaHfusion

Re: Heating curve

Posted: Sun Feb 16, 2020 3:11 pm
by Juliana Chopelas 1A
When a phase change is happening you will use q=mdeltah or q=ndeltah depending on whether you are given mass or moles. When the substance is heating up or the diagonal line on the curve, you will used q=mcdeltaT or q=ncdeltaT once again depending on whether you are given moles or mass.

Re: Heating curve

Posted: Sun Feb 16, 2020 3:37 pm
by Charysa Santos 4G
Phase changes correlate to the plateau of a heating curve, and there, you can use q = mΔh if you are given mass or q = nΔh if you are given moles. If you are calculating the diagonal/rise in temperature, you will use q = mCΔT or q = nCΔT.

Re: Heating curve

Posted: Sun Feb 16, 2020 7:13 pm
by Kennedi2J
There technically is no temperature change at the plateaus where phase changes occur (i.e. melting is 0 degrees---> 0 degrees). For phase changes you use q=m(delta H) and for a temperature change you use q= mCAT.

Re: Heating curve

Posted: Sun Feb 16, 2020 10:09 pm
by Alondra
Phase changes --> use q=m(delta H)

Temperature change --> use q= mCAT