LAS 1: UNITS OF MEASUREMENT & ITS CONVERSION, SIGNIFICANT FIGURES AND PERCENTAGE YIELD

Measurements

a process of finding the number that shows the size or

quantity of something which is usually given in terms of a specific unit.

Measurements

is the

determination of the dimensions, capacity, quantity, or extent of

something

English System

Metric

The two systems used for specifying units of measure

The metric system

International System of Units (SI).

is a decimal system of measurement developed by the

french in the 18th century.

1. meter

2. Kilogram

3. seconds

4. ampere

5. Kelvin

6. mole

7. candela

There are 7 base units, they are regarded as dimensionally independent:

Unit

Meter

Kilogram

S e c o n d s

Ampere

Kelvin

Mole

Candela

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Symbol

m

K g

s

A

K

mol

cd

Quantity

Length

Mass

Time

Electric current

Temperature

A m o u n t if s u b s t a n c e

Luminous intensity

UNIT & SYMBOL?

Meter

the base unit of length in the metric system.

Gram

the base unit of mass in the metric system.

Liter

is the base unit of

volume in the metric system.

Dimensional analysis

factor-label method or

unit conversion method

is a problem-solving technique used in physics,

chemistry, engineering, and everyday life to convert one set of units to

another, check the consistency of equations, and derive relationships

between physical quantities

English system

(also called the Imperial system or US Customary system)

is a collection of measurement units that originated in England and

were later adopted (with some variations) in the United States.

Arbitrary (12 in/ft, 16 oz/b)

Decimal (powers of 10)

Key Differences Between English and Metric Systems

BASE SYSTEM

Mainly US, Liberia, Myanmar

A l m o s t all countries

Key Differences Between English and Metric Systems

GLOBAL USE

Complex (e.g., 5,280 ft/mi)

Simple (e.g., 1 km = 1,000 m)

Key Differences Between English and Metric Systems

CONVERSIONS

Rarely u s e d

S t a n d a r d worldwide

Key Differences Between English and Metric Systems

SCIENTIFIC USE

Significant figures or significant digits

meaningful digits in a measured or calculated number that contribute to its precision. They indicate how accurately a number is known.

theoretical yield,

which is the amount of the

product calculated from the limiting reactant.

The limiting reactant

is the reactant in the chemical reaction which limits the amount of

product that can be formed.

actual yield

is the actual amount produced when the experiment or reaction is carried out.

Percent Yield

The

discrepancy between the theoretical yield and the actual yield can be

calculated using the