Module 2 Pretest Homework Packet Answers
Module Two-Part 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?
____???____ cm3
= 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 = L3 = 5.00 cm X 5.00 cm X 2.50 cm = ____62.5__cm3
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 7th 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 oC to 54.9 oC.
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 ∙ oC |
q = C ∙ m ∙ ∆t
∆t = 54.9 oC
– 27.7 oC
= 27.2 oC
25.0 cal |
|
|
|
|
( |
cal |
) |
----------------------- |
= |
Specific Heat |
= |
0.0306 |
-------- |
||
30.0 g ∙ 27.2 oC |
|
|
|
|
g ∙ oC |
2. Calculate
the heat required to raise to raise 25.0 g of iron (sp Heat=0.108 cal/g ∙
oC) from 25.0 oC
to 50.0 oC.
q = C ∙ m ∙ ∆t
q = (0.108 cal/g ∙ oC)
(25.0 g) (50.0 oC – 25.0 oC )
q = 0.108 ∙ 25.0 ∙ 25.0 cal
q = 67.5 cal
Old Text References:
McMurry 6th 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 2.64-2.71.
Corwin 5th 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 7th See
Section 11.6 pages 322-324. New text removes specific heat problems from
Chapter 2.