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 a 30.0 g sample has a heat capacity of 3.00 J/K? A. 0.100 J oC-1 g-1, B. 90.0 J g K-1, C. 10.0 J-1 K g Specific heat is short for “specific heat capacity” Specific heat, s, is heat capacity per gram s = C/m Given: C = 3.00 J/K, m = 30.0 g s = C/m = (3.00 J/K) / (30.0 g) = 0.100 J /K /g, = 0.100 J /oC /g = 0.100 J oC-1 g-1 What is the specific heat of a substance if a 30.0 g sample has a heat capacity of 3.00 J/K? Is it A… 0.100 joule per degree celsius per gram Or B.. 90.0 joule gram per kelvin Or C…10.0 per joule kelvin gram PAUSE CLICK Specific heat is actually short for specific heat capacity. The adjective specific… HIGHLIGHT specific in “specific heat capacity” as used in science, generally means per gram. CALLOUT “means per gram” pointing to highlighted term CLICK So specific heat capacity means heat capacity per gram. CLICK Since specific heat is heat capacity per gram, we 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 We are given that the heat capacity is 3.00 joule per kelvin. HIGHLIGHT 3.00 J/K in given line and in problem We are also given that the mass is 30.0 grams. HIGHLIGHT 30.0 g in given line and in problem CLICK Therefore, the specific heat is equal to … …the heat capacity… 3.00 joule per kelvin HIGHLIGHT divided by… HIGHLIGHT “/” the mass of the sample… 30.0 grams. HIGHLIGHT Carrying out the indicated calculation gives us a specific heat of 0.100 joule per kelvin per gram Since a temperature change of one kelvin corresponds to a one degree change on the Celsius scale, we can also say that the specific heat is 0.100 joule per degree celsius per gram HIGHLIGHT “J /oC /g” Or we can say write the unit as joules…. times reciprocal celsius degree… times reciprocal gram. Therefore the correct answer is choice A. CLICK PAUSE END RECORDING

Video ID: 8-4-1 © 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.