Specific heat is short for “specific heat capacity”

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Presentation transcript:

Specific heat is short for “specific heat capacity” QUESTION: What is the specific heat of a substance if the temperature of a 35.0 g sample increases from 25.0oC to 27.0oC with the absorption of 14.0 J of heat? A. 0.400 J g-1, B. 7.0 J K-1, C. 0.200 J K-1 g-1 Specific heat is short for “specific heat capacity” Specific heat, s, is heat capacity per gram s = C/m Heat capacity = heat per unit change in temperature C = q/T Therefore C = (14.0 J) / (2.0K) = 7.0 J/K s = (7.0 J /K) / (35.0 g) = 0.200 J /K /g = 0.200 J K-1 g-1 What is the specific heat of a substance if the temperature of a 35.0 g sample increases from 25.0oC to 27.0oC with the absorption of 14.0 J of heat? Is it A… 0.400 joule per gram B… 7.0 joule per kelvin Or C… 0.200 joule per kelvin per gram PAUSE CLICK Specific heat, which is short for specific heat capacity, means heat capacity per gram. CLICK Therefore, we can calculate it by dividing the heat capacity, HIGHLIGHT C in “C/m” CALLOUT “heat capacity” pointing to C in “C/m” by the mass of the sample HIGHLIGHT m in “C/m” CALLOUT “mass” pointing to C in “C/m” CLICK Heat capacity is the amount of heat needed to raise the temperature of a sample by one degree Celsius, or one Kelvin. CLICK To calculate heat capacity, we simply divided the amount of heat flow HIGHLIGHT q By the temperature change… HIGHLIGHT T Therefore, the heat capacity is equal to …. The amount of heat flow… 14.0 joules HIGHLIGHT 14.0 J Divided by … HIGHLIGHT “/” the temperature change… 2.0 kelvin. HIGHLIGHT 2.0K which gives us 7.0 joule per kelvin. CLICK To calculate specific heat, we dividethe heat capacity…7.0 joule per Kelvin HIGHLIGHT 7.0 J/K by the mass of the sample… 35.0 grams HIGHLIGHT 35.0 g to get a value of 0.200 joule per kelvin CALLOUT “or K-1” pointing to /K per gram CALLOUT “or g-1” pointing to /g. Therefore the correct answer is choice C. CLICK PAUSE END RECORDING

Video ID: 8-4-2 © 2008, Project VALUE (Video Assessment Library for Undergraduate Education), Department of Physical Sciences Nicholls State University Author: Glenn V. Lo Assisted by Johuan Gasery In partial fulfillment of the requirements for CHEM 481, Fall 2008.