CHEM 1030 Chapter E: Units and Measurements

Qualitative observations

Descriptive in nature

Quantitative observations

Numerical values obtained from different measuring devices

Numerical value

Reflects the precision of the instrument or piece of glassware used to make the measurement

Systematic/Determinate Error

• Error is in the same direction

• Higher or lower than should be

Random/Indeterminate Error

• Equal probability of measure being lower or higher than should be

• Difficult to correct or find source

Length

meter (m)

Mass

kilogram (k)

Time

seconds (s)

Temperature

kelvin (k)

Amount of substance

mole (mol) 6.02 × 10²³ units

Electric Current

ampere (A)

Luminous Intensity

candela (cd)

tera (T)

10¹²

giga (G)

10⁹

mega (M)

10⁶

kilo (K)

10³

hecto (h)

10²

deka (da)

10¹

deci (d)

10^-1

centi (c)

10^-2

milli (m)

10^-3

micro (μ)

10^-6

nano (n)

10^-9

pico (p)

10^-12

What is the formula used to convert from Fahrenheit to Celsius?

°F = 9/5 (°C) + 32

What is the formula used to convert from Kelvin to Celsius?

K = °C + 273.15

Precision

Agreement or closeness of a series of measured values

Accuracy

Agreement or closeness of measured value/s to actual known value

Reporting of significant figures in an answer depends on the _________________ of the MEASURED values given in the problem.

precision

Conversion factors, number used to change one set of units to another, are treated as ______ values.

exact

All nonzero values _________ significant

are

Zeroes between nonzero digits __________ significant

are

Leading zeroes to the left of a nonzero digit _________ significant

are not

Zeroes to the right after a nonzero digit _______ significant

are not

Zeroes to the right after a decimal place _____ significant

are

When multiplying or dividing, the answer should have the same number of sig fig as the number with the _____________.

least amount of sig figs

When adding or subtracting, the answer should have the same number of decimal places as the number with the __________.

least amount of decimal places

50,003 has ____________ sig figs

5

0.9785 has ____________ sig figs

4

Intensive properties are ____________ of size

independent

Extensive properties are ______________ on size

dependent

Density = _____/______

Mass/Volume

Density is an ____________ property

intensive

Energy is

the capacity to do work

Work

the action of a force applied across a distance

Finish the formula: KE = ___________

1/2m(v²)

True or False: m = kg

True

Energy units

kg*m²/s²

Energy is measured in _______________

Joules (J)