Measurement: quantity with _______ and a _____. 42.5 g1.05 mL16 cm Measurement unit number.

measurement:quantity with _______ and a _____.

42.5 g 1.05 mL 16 cm

Measurement

unitnumber

a really big number: 100,000,000,000,000

(atoms in a cell)

or really small number: 0.000 000 000 01 meter

(size of one atom)

can be written without zeroesby using powers of 10.

ScientificNotation

100,000,000,000,000 = 1 x 1014 atoms (atoms in a cell)

0.000 000 000 01 meter = 1 x 10–11 meters (size of an atom)

ScientificNotation

AccuratePrecise _______________

Accurateand

Precisebut not

Neither PreciseNor

Accurate

Accuracy:how close to the actual or true value

Accuracy, Precision, and % Error

Precision:how close to each other (repeatable)

Error

% Error = (________) x 100 acc

Accuracy, Precision, and % Error

exp – acc

exp – experimental valueacc – accepted value

What is the % error if a measurement of 99.1oC is made, but the true temperature is 100.0oC?

% Error Calculation:

1. Which of the following expressions has NOT been correctly changed to sci. not.?

A. 0.00456 = 4.56 10–3

B. 0.0000254 = 2.54 10–5

C. 8,426,000 = 8.426 106

D. 45,200 = 4.52 103

Quick Quiz!

2. Which set of measurements of a 2.00-g object is the most precise?

A. 2.00 g, 2.13 g, 1.92 g

B. 2.10 g, 2.00 g, 2.20 g

C. 2.05 g, 2.04 g, 2.05 g

D. 1.50 g, 2.00 g, 2.50 g

Quick Quiz.