CHAPTER 1



SCIENTIFIC MEASUREMENT Name__________________________________Per___

A measurement is a quantity that has both a ______________________ and a ______________.

The units of measurements used in science are those of the _____________________________.

The International System of Units (SI) is a revised version of the metric system.

| | | |

|Quantity |SI Base Unit |Symbol |

|Length | | |

|Volume | | |

|Mass | | |

|Temperature | | |

|Time | | |

|Amount of Substance | | |

Prefixes Used with SI Units

|Prefix |Symbol |Factor |  |Example |

|giga |  |  |  | gigabyte ( ) |

|mega |  |  |  | megabyte ( ) |

|kilo |  |  |  |  |

|hecto |  |  |  |  |

|deka |  |  |  |  |

|  |  |  |  |  |

|deci |  |  |  |  |

|centi |  |  |  |  |

|milli |  |  |  |  |

|micro |  |  |  | microgram ( ) |

|nano |  |  |  | nanosecond ( ) |

|pico |  |  |  | picometer ( ) |

Length:

1 km =_________m 1mm = __________m 1 m = _________dm 1 cm =_________mm

Volume: 1 L = ________mL 1 kL = __________L 1 uL= ________L 1cm3 = ______mL

Mass:

1 kg =________g 1g = ________mg 1 g = _____ug 1 g = ______ng 1 ug = _______g

Preforming Conversions: by moving the decimal

| | | |

|   |Alex |Melissa |Alan |

|Weighing 1 |11.97 |11.37 |11.98 |

|Weighing 2 |12.01 |11.39 |10.97 |

|Weighing 3 |11.99 |11.34 |11.33 |

|Weighing 4 |12.06 |11.41 |12.08 |

Significant Figures

When making scientific measurements, you must be aware of how many digits in the number representing a measurement are significant.

The significant figures in a measurement include all of the digits that are known, plus a last digit that is estimated.

Ex: 145 lbs _________________ 98.7° F ___________________ 6.04 kg __________________

The following rules apply when determining the number of significant digits:

1. All non-zero digits are significant. 13,438 ….. ___ ; 75….___ ; 24.45…. ___

2. Any zeros between nonzero digits are significant. 1,406…___ ; 40.79…___ ; 8004…___

3. All final zeros to the right of the decimal are significant. 12.0…___ 8.50…___ 27.00… ___ 4. Zeros as place holders are not significant. 27000… ___ ; 100…___; 0.000012…___

5. There two situations in which numbers have an infinite number of sig figures.

a) counting numbers: 23 people, 2 dozen, 3 moles.

b) defined quantities (SI) : 100 cm, 60 sec, 1000 mg

SCIENTIFIC MEASUREMENT (4) Name__________________________________Per___

How many significant figures are in the following measurements:

a. 2000 L ____ k. 0.000098 dm ____ u. 8 x 102 kg ____

b. 340 m ____ l. 4,000,000 dam____ v. 2.4 x 104 km ____ c. 105 g ____ m. 9200 hm____ w. 3.45 x 10-8 g____

d. 8061 ms ____ n. 2.408 kg____ x. 4.00 x 102 m ____

e. 80 ug ____ o. 1099 mL ____ y. 1.50 x 10-3 s____

f. 3060 mL ____ p. 0.00005 µL ____ z. 508.0 g _____

g. 0.0081 µg ____ q. 1008 s ____ ab. 15,001 km _____

h. 0.019 mm____ r. 1,000,485 km____ ac. 28,010,000 m_____

i. 0.109 ms____ s. 0.000908 nm ____ ad. 0.0092900 g_____

j. 0.880 km____ t. 6.4080 pg_____ ae. 300 s _____

Rounding Off Numbers

Rules: There are three sig figs in each example below

• If the digit to the immediate right of the last sig fig is less than five, do not change the last sig fig. 2.532

• If the digit to the immediate right of the last sig fig is greater than five, round up the last sig fig. 2.536

• If the digit to the immediate right of the last sig fig is equal to five and is followed by a nonzero digit, round up the last sig fig. 2.5351

• If the digit to the immediate right of the last sig fig is equal to five and is followed by a zero, look at the last sig fig. If it is odd digit, round it up. If it is an even digit, do not round it up.

2.5350 but 2.5250

Round off each measurement to the number of significant figures shown in parentheses.

a. 3.515014 (five) __________________ m. 98927 m (two) __________________

b. 3.515014 (three) __________________ n. 178223 km (two) _________________

c. 3.515014 (one) __________________ o. 694 s (two) ____________________

d. 0.00081119 g (four) _________________ p. 0.00473 s (two) __________________

e. 356750 km (four) __________________ q. 0.006773 s (two) __________________

f. 0.00087147 s (three) ________________ r. 0.000556 g (one) __________________

g. 337289 m (three) _________________ s. 0.0322 m (one) __________________

h. . 41.879 s (three) __________________ t. 8.22 m (one) __________________

i. 328.72 mL (three) __________________ u. 3.569 g (one) __________________

j. 489 s (two) __________________ v. 28 m (one) __________________

k. 9257 mL (two) __________________ w. 333 m (one) __________________

l. 28 s (one) __________________ x. 4889 m (one) __________________

Significant Figures in Calculations

A calculated answer cannot be more precise than the least precise measurement from which it was calculated. The answer must be rounded to the same number of sig fig as least precise #.

Rules for Rounding Calculated Answers:

1. When adding or subtracting measurements, the answer should be rounded to the same number of decimal places as the measurement with the least number of decimal places. Ex: 55.4598 g + 64.23 g = 119.6898 g =

2. When multiplying or dividing two measurements, round the answer to the same number of significant figures as the measurement with the least number of significant figures. Ex: 3.86 cm x 2.2 cm = 8.492 cm2 =

Perform the following calculations and give answers to the correct number of significant figures:

a. 2.9 mg + 3.8 mg + 1.8 mg = _____________ q. 24 m x 3.36 m = ___________

b. 2.58 g + 3.8 g + 1.088 g = _____________ r. 125 m x 0.10 m = ___________

c. 258.92 m + 300.8 m + 289 m = ___________ s. 255 m ÷ 2.15 s = ___________

d. 0.06888 s - 0.058 s = _______________ t. 4.75 g ÷ 3.0065 mL = ____________

e. 0.0005 ng - 0.0004709 ng = ______________ q. 1.56 mm x 2.0 mm = ____________

f. 8.8 x 104 L - 5.33 x 104 L = ________________ r. 84.6 m ÷ 22 s = ____________

g. 4.895 x 104 km + 3.3 x 104 km = _____________ s. 8.45 km x 1.6 k m = ___________

h. 6.677 x 104 km + 8.2 x 104 km = ______________ t. 1.210 x 106 g ÷ 2.4 x 103 mL = _______

i. 3.90 x 106 g + 6.9990 x 105 g = ______________ u 8.0 x 102 m x 4.0 x 103 m = _______

j. 9.6351 x 104 km - 5.10 x 104 km = ______________ v. 102.1 m ÷ 51.4 s = ____________

k. 8.74 x 109 L - 6.055 x 109 L = ______________ w. 25 km x 3.3 km = ______________

l. 24 g + 38 g + 9 g = ________________ x. 1.860 x 103 km ÷ 2.4 x 10 1hr = ______

m. 12 m + 23 m + 42.5 m = ______________ y. 2.245 m x 1.2 m = _____________

n. 3.7 g + 2.83 g + 9.327 g = ___________ z. 2.7968 g ÷ 8.6 mL = ____________

o. 89.49 s - 40.2 s = ______________ ab. 8 m x 4 m = ______________

p. 45.23 g + 24.4798 g + 38.028 g = _____________ ac. 1877 m ÷ 3 s = ___________

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