PreTest: Steps 1, 2 and 3 Answers: Name: ___________________

CHEM 1001/CHM1020/CHM1025C/CHM1032C  Module 2 Part F Unit Analysis Problems 10pts

You may use a calculator. Please use the Unit Analysis or Dimensional Analysis method to solve ONLY TWO of the following word problems:


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Problem #1:

1. An oxygen molecule travels 975 mi/hr at room temperature. There are 5280 ft = 1 mi; 12 in = 1 ft, 2.54 cm = 1 in, 1.621 km = 1 mi, and 3600 sec = 1 hr. What is the velocity in meters per second?

The Question:

____???____ m/sec = 975 mi/hr

Given Unit Factors

 

The Solution:

1. On the Numerator:
      Change m to km to miles
or change m to cm to inches to feet to miles
2. then on the denominator:
      change hours to seconds or change hours to minutes to seconds

 

 

??? m

=

975 mi

X

1.621 km

X

1000 m

X

1 hr

=

439 m

 







1 sec

1 hr

1 mi

1 km

3600 sec

1 sec

 

 


 

Problem #2:

2. If one gram is equal to 15.4 grains. How many 5.00 grain aspirin tablets may be made from 1.00 kilogram of aspirin?

The Question:

____???_____ tab = 1.00 kg

Given Unit Factors



Change kg to g to grains to tablets!

The Solution:

 

 

??? tab

=

1 kg

X

1000 g

X

15.4 grain

X

1 tab

=

3080 tab

 







1

1

1 kg

1 g

5 grain

1

 

 


 

Problem #3:

3. A parsec is the distance light travels in 3.26 years. Given the velocity of light, 3.00 x 108 m/sec, how many kilometers does light travel in one parsec?

The Question:

____???_____ km = 1 parsec

The Solution:

Given Unit Factors



change parsec to years to days to hours to minutes to seconds to meters then to kilometers

 

 

??? km

=

1 parsec

X

3.26 yr

X

365 day

X

24 hr

X

3600 sec

X

3.00 X 108 m

=

3.08 X 1013 km

 









1

1

1 parsec

1 yr

1 day

1 hr

1 sec

1

 

 


 

Problem #4:

4. I have 1400 radio programs I want to put on an Apple Ipod. Each program requires 5 megabytes of disk space. If there are 1024 megabytes in a gigabyte. How many gigabytes of disk space do I need minimum to store all my programs on the IPod. The Mini-Ipod holds only 4 gigabytes of recordings, could I use a mini for my project?

The Question:

____???_____ Gb = 1400 programs

Given Unit Factors



Change programs to megabytes to gigabytes

The Solution:

 

 

??? Gb

=

1400 Program

X

5 Mb

X

1 Gb

=

6.84 Gb

 






1

1

1 Program

1024 Mb

1