Module 2 Pretest Homework Packet Answers
Module TwoPart H: Density, Specific Gravity & Volume
Problems 5
points
1. A quartz rock was cut into a rectangular solid paperweight.
IF the paperweight has a mass of 165 g and measures 5.00 cm by 5.00 cm by 25.0
mm, what is its volume in cubic centimeters?
____???____ cm^{3}
= 5.00 cm X 5.00 cm X 25.0 mm
10 mm = 1 cm ;
therefore 25.0 mm = 2.50 cm (all units
must be equal)
Volune = L^{3} = 5.00 cm X 5.00 cm X 2.50 cm = ____62.5__cm^{3}
2. Calculate the density in g/mL for
10.0 grams of ethyl ether having a volume 14.0 mL.
Density = ____???____ g/m
Density = Mass/Volume = 10.0 g/14.0 mL = 7.14 g/mL
Additional Homework (not required) for your practice:
Corwin 7^{th} edition:
Page 60:
#43#46; #47  #58
Part I: Heat and
Specific Heat 5 points
1. Find
the specific heat of gold if 25.0 cal is required to heat 30.0 g of gold from
27.7 ^{o}C to 54.9 ^{o}C.
Specific heat is the
amount of heat required to raise the temperature of one gram of a substance one
degree Celsius.
Heat (cal) 


( 
cal 
) 
 
= 
Specific Heat (C) 
 

Mass (g) ∙
Temperature Change (∆t) 


g ∙ ^{o}C 
q = C ∙ m ∙ ∆t
∆t = 54.9^{ oC}
– 27.7^{ oC}
= 27.2 ^{o}C
25.0 cal 




( 
cal 
) 
 
= 
Specific Heat 
= 
0.0306 
 

30.0 g ∙ 27.2 ^{o}C 




g ∙ ^{o}C 
2. Calculate
the heat required to raise to raise 25.0 g of iron (sp Heat=0.108 cal/g ∙
^{o}C) from 25.0 ^{o}C
to 50.0 ^{o}C.
q = C ∙ m ∙ ∆t
q = (0.108 cal/g ∙ ^{o}C)
(25.0 g) (50.0^{ }^{o}C – 25.0 ^{o}C )
q = 0.108 ∙ 25.0 ∙ 25.0 cal
q = 67.5 cal
Old Text References:
McMurry 6^{th} 1032C text: Chapter 2 Section 2.10 see worked
example 2.13 page 38, then try problems 2.20 and 2.21 page 39. End of Chapter
page 46 Problems 2.642.71.
Corwin 5^{th} CHM
1025C text Chapter 3 Section 3.9 see worked example 3.19 page 64; then try the
practice exercise on page 64. Additional problems end of chapter page 69:
#57#64.
Corwin 7^{th} See
Section 11.6 pages 322324. New text removes specific heat problems from
Chapter 2.