Neely's Chemistry Dimensional Analysis USING DIMENSIONS TO  CONVERT UNITS  SOLVE PROBLEMS

Neely's Chemistry Review: Multiplying Fractions What is What is A x 3 A = ? ANS: A’s cancel giving ANS: A’s cancel giving 3 as the answer 3 as the answer

Neely's Chemistry Review: Multiplying Fractions What is What is 2 ft x 12 in 1 ft = ? ANS: ft cancels giving ANS: ft cancels giving 2x12/1 = 24 in 2x12/1 = 24 in as the answer as the answer

Neely's Chemistry Dimensional Analysis Uses dimensions or units to solve problems Uses dimensions or units to solve problems General Math Rule: Do the same thing with the units that you do with the numbers General Math Rule: Do the same thing with the units that you do with the numbers Ex: 2 m x 3 m = ? Ex: 2 m x 3 m = ? ANS: 6 m 2 ANS: 6 m 2 since 2 x 3=6 & m x m=m 2 since 2 x 3=6 & m x m=m 2

Neely's Chemistry Dimensional Analysis Read the question carefully Read the question carefully Identify the GIVEN and the UNITS of the UNKNOWN Identify the GIVEN and the UNITS of the UNKNOWN

Neely's Chemistry Dimensional Analysis Read the question carefully Read the question carefully Identify the GIVEN and the UNITS of the UNKNOWN Identify the GIVEN and the UNITS of the UNKNOWN Set up the TRACK (“RR Track”) Set up the TRACK (“RR Track”) Cancel units you don’t want & insert units you want. Cancel units you don’t want & insert units you want. = UNITS GIVEN

Neely's Chemistry How many yards is 54 inches?

Neely's Chemistry How many yards is 56 inches? GIVEN = 54 in GIVEN = 54 in UNITS for unknown = yd UNITS for unknown = yd Track: Track: Don’t want inches in final answer Don’t want inches in final answer What do you know that will get the desired units? What do you know that will get the desired units? 1 ft = 12 in & 3 ft = 1yd 1 ft = 12 in & 3 ft = 1yd = 54 in in 1 ft 123 ft 1 yd 1.5 yd

Neely's Chemistry Congratulations! Now you have solved a unit conversion problem by dimensional analysis ! Congratulations! Now you have solved a unit conversion problem by dimensional analysis !

Neely's Chemistry Let’s Solve a Word Problem The density of mercury is 13.5 g/mL. What volume of mercury in L would weigh 2700 g? The density of mercury is 13.5 g/mL. What volume of mercury in L would weigh 2700 g?

Neely's Chemistry The density of mercury is 13.5 g/mL. What volume of mercury in L would weigh 2700 g? The density of mercury is 13.5 g/mL. What volume of mercury in L would weigh 2700 g? 2700 g 13.5 g 1 mL 1000 mL 1 L = 0.20 L Congratulations! Now you have solved a word problem by dimensional analysis ! Congratulations! Now you have solved a word problem by dimensional analysis !

Neely's Chemistry 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 10 3 mm 1 m10 2 cm 1 m = ?

Neely's Chemistry PRACTICE : o How many hours in a year? o The Baconater from Wendy’s has 8 strips of bacon. How many strips of bacon are there in 16 Baconaters? o It is 5954 m from KHS to Hwy 59. How many miles is that? (There are 1.61 km in a mile.)

Neely's Chemistry Time to work on the Dimensional Analysis Practice WS