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it have the correct units?
EXAMPLE 1.11 Conversions with SI Prefixes
Express the following amounts using prefixes from the SI.
a. Convert 827 m to kilometers.
b. Convert 257 mg to micrograms.
•Method of Solution for (a)
Conversions within the SI are based on knowing the SI prefixes. First state the problem in the format:
desired quantity = given quantity × conversion factors.
? km = 827 m
Our road map is: m → k m
The relationship is 103 m = 1 km, which leads to two possible conversion factors:
1 km 1 km
Choose the one that allows cancellation of the unit m.
and ? km = 827 m × 1 km
103 m ? km = 0.827 km
•Method of Solution for (b)
First state the problem:
? µm = 275 mg Back Forward Main Menu TOC Study Guide TOC Textbook Website MHHE Website Chemistry: The Study of Change / 1 7
Since we know how many mg are in a gram and how many µg are in a gram, we will convert mg to grams
and then grams to µg.
Road map: mg → g → µ m
? µm = 275 mg × 10–3 g
mg × 1 µg
= 275 × 10 3 µg
10–6 g ? µ...
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- Spring '08
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