CHEM 1001/CHM1020/CHM 1025C/CHM 1032C - Steps 1 and 2 Answers       Name:_____________

Module Two-Part F: Unit Analysis Problems       10 points


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Apply the unit analysis method of problem solving to each of the following (setup statement 1 pt, unit analysis setup 3 pts, answer 1 pt with its proper unit) (If greater than three significant figures round off to three significant figures):


(1) How many karats is a diamond weighing 234.2 mg? (One karat = 0.200 g)

The Question:

____???____ karat = 234.2 mg

Given Unit Factors

  • 1 karat = 0.200 g

Unit Factors Not Given

  • 1 g = 1000 mg




The Solution:

 

 

??? karat

=

234.2 mg

X

1 g

X

1 karat

=

1.17 karat

 






1

1

1000 mg

0.200 g

1

 


(2) Insurance statistics state that a person loses 8 minutes of average life for each cigarette smoked. If there are 20 cigarettes in a pack and the average cost of cigarette is $4.50 per pack over the next 15 years, how many years of average life would a person lose for smoking 1.5 packs a day for 15 years?

The Question:

____???____ yrlifelost = 15 yrsmoking

Given Unit Factors

  • 1 cig = 8 minlifelost
  • 1 pack = 20 cig
  • 1 pack = 4.50 dollars
  • 1 day = 1.5 packsmoking

Unit Factors Not Given

  • 1 yr = 365 days (or 365.25 days)
  • 1 day = 24 hr
  • 1 hr = 60 min

 

The Solution:

The important brdge between life lost and smoking is the 8 minutes lost = 1 cig smoked Unit Factor.

 

 

??? yrlifelost

=

15 yrsmok

X

365 daysmok

X

1.5 pack

X

20 cig

X

8 minlost

X

1 hrlost

X

1 daylost

X

1 yrlost

=

2.5 yrlifelost

 











1

1

1 yrsmok

1 daysmok

1 pack

1 cig

60 minlost

24 hrlost

365 daylost

1

 

 


 

Module Two-Part H: Density, Specific Gravity & Volume Problems 10 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?

The Question:

____???____ 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.

The Question:

Density = ____???____ g/m

Density = Mass/Volume = 10.0 g/14.0 mL = 7.14 g/mL




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