Chemistry Chapter E (Quiz 1)

Week 1, 2, & 3

Every Measurement Involves comparing…

that which is to be measured with a measuring device

Every Measured Quantity has 3 Parts

1.) Numerical Value

2.) Unit

3.) Uncertainty ex. 17.3685 ± .00002g

2 Most Common Unit Systems

Metric Developed in France in the 1700’s

English developed in the U.S.

Scientists use International System of Units (SI)

Prefix Examples

mg, kg, Mg, qg, pg

Counted Quantities vs Measured Quantities

They are certain & they are uncertain

Mass vs Weight

Quantity of Matter vs force of gravitational pull

Mass does NOT change, weight changes based on gravitational pull

Newtons 2nd Law

how many fundamental quantities are there in SI

7

Formula for weight of force

= Mass x Acceleration

Temperature

Measure/degree of hotness/coldness of matter & a measure of avg kinetic energy

3 Temperature Scales

Celcius, Fahrenheit, and Kelvin

Intensive Properties

Does not depend on amount of substance

Extensive Properties

Depends on amount of substance

Energy

The capacity to do work

Work Formula

force x displacement (ma) x (deltax)

Kinetic Energy

Energy of motion

Potential Energy

Energy by the virtue of position, condition, or composition

Types of energy

chemical, electrical, light, mechanical, nuclear, sound & thermal

Thermal Energy

Energy associated with the temperature of an object (a form of kinetic energy)

Conservation of Energy

Energy is always conserved in a physical or chemical change; neither created nor destroyed

Which direction do systems with high potential energy (less stable) move to?

Change in the direction that lowers the potential energy i.e. (releasing their energy to surroundings)

Exothermic Process

(-) Releases energy from system to surroundings

Endothermic Process

(+) Takes energy from surroundings into the system

Accuracy

How close a measured value is to the actual value

Precision

How close a series of measured values are to each other

Relative Error Formula

(E-A)A

Percent Relative Error

{(E-A)/A} x 100

Exact, counted numbers have how many sig figs

Unlimited

Unit Equation

A statement of 2 equivalent quantities

Conversion Factor

A fractional quantity of a unit equation with the units we are converting from on the bottom to the units were converting to on the top