## 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:

## 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

• 5280 ft = 1 mi
• 12 in = 1 ft
• 2.54 cm = 1 in
• 1.621 km = 1 mi
• 3600 sec = 1 hr

### 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

• 1 g = 15.4 grain
• 1 tab = 5.00 grain

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

### Given Unit Factors

• 1 parsec = 3.26 yr
• 3.00 x 108 m = 1 sec

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

• 1 program = 5 Mb
• 1024 Mb = 1 Gb

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