Dimensional Analysis

Neely's ChemistryNeely's Chemistry

Dimensional AnalysisDimensional Analysis

USING DIMENSIONS TOUSING DIMENSIONS TOCONVERT UNITSCONVERT UNITSSOLVE PROBLEMSSOLVE PROBLEMS


Review: Multiplying FractionsReview: Multiplying Fractions

What is What is A x

3

A= ?

ANS: A’s cancel givingANS: A’s cancel giving

33 as the answeras the answer


Review: Multiplying FractionsReview: Multiplying Fractions

What is What is 2 ft x 12 in

1 ft= ?

ANS: ft cancels givingANS: ft cancels giving

2x12/1 = 24 in2x12/1 = 24 in as the answeras the answer



Uses dimensions or units to solve Uses dimensions or units to solve problems problems

General Math Rule: Do the same thing General Math Rule: Do the same thing with the units that you do with the with the units that you do with the numbersnumbers

Ex: 2 m x 3 m = ?Ex: 2 m x 3 m = ?ANS: 6 mANS: 6 m22

since 2 x 3=6 & m x since 2 x 3=6 & m x m=mm=m22



Read the question carefullyRead the question carefully Identify the GIVEN and the UNITS of Identify the GIVEN and the UNITS of

the UNKNOWNthe UNKNOWN



Read the question carefullyRead the question carefully Identify the GIVEN and the UNITS of the Identify the GIVEN and the UNITS of the

UNKNOWNUNKNOWN Set up the TRACK (“RR Track”)Set up the TRACK (“RR Track”)

Cancel units you don’t want & insert units Cancel units you don’t want & insert units you want.you want.

= UNITS GIVEN


How many yards is 54 How many yards is 54 inches?inches?


How many yards is 56 How many yards is 56 inches?inches?

GIVEN = 54 inGIVEN = 54 in UNITS for unknown = ydUNITS for unknown = yd Track: Track:

Don’t want inches in final answerDon’t want inches in final answer What do you know that will get the desired What do you know that will get the desired

units?units? 1 ft = 12 in & 3 ft = 1yd1 ft = 12 in & 3 ft = 1yd

= 54 in

in

1 ft

12 3 ft

1 yd 1.5 yd


Congratulations! Now you have Congratulations! Now you have solved a unit conversion problem by solved a unit conversion problem by dimensional analysisdimensional analysis!!


Let’s Solve a Word ProblemLet’s Solve a Word Problem

The density of mercury is 13.5 g/mL. The density of mercury is 13.5 g/mL. What volume of mercury in L would What volume of mercury in L would weigh 2700 g?weigh 2700 g?


The density of mercury is 13.5 The density of mercury is 13.5 g/mL. What volume of mercury in L g/mL. What volume of mercury in L would weigh 2700 g?would weigh 2700 g?

2700 g

13.5 g

1 mL

1000 mL

1 L= 0.20 L

Congratulations! Now you have solved a Congratulations! Now you have solved a word problem by word problem by dimensional analysisdimensional analysis!!


Convert 300 mm to cm.Convert 300 mm to cm.Hint – when doing metric conversions, use an equivalency

that will take you to home base before heading out to the

unit you want to find.

300 mm

103 mm

1 m 102 cm

1 m= ?


PRACTICE :PRACTICE :o How many hours in a year?How many hours in a year?

o The Baconater from Wendy’s has 8 The Baconater from Wendy’s has 8 strips of bacon. How many strips of strips of bacon. How many strips of bacon are there in 16 Baconaters?bacon are there in 16 Baconaters?

o It is 5954 m from KHS to Hwy 59. It is 5954 m from KHS to Hwy 59. How many miles is that? (There are How many miles is that? (There are 1.61 km in a mile.)1.61 km in a mile.)


Time to work on the Time to work on the Dimensional Analysis Practice Dimensional Analysis Practice

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Dimensional Analysis

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