AP ChemistryPreface and Chapter

1Matter and Measurement

Mrs. Alvarez

Definition: Mass per unit volume of a substance

Formula: D = m/V ; units: g/mL, g/cm3, kg/L

Density

Sample Problem A piece of copper has a mass of 57.54 g. It is 9.36 cm long, 7.23 cm wide, and 0.95 mm thick. Calculate density (g/cm3).

Sample Problem

2. Use of density as a conversion factor:

Sample Problem: Mercury (Hg) has a density of 13.6 g/cm3. What is the mass of 95 mL of Hg in grams? In pounds?

First, note that 1 cm3 = 1 mL Strategy1.Use density as a conversion factor to calculate mass (g)

from volume.

2.Convert mass (g) to mass (lb)

Need to know conversion factor; 454 g = 1 lb

Density as a conversion factor

Density of water changes with temperature – why?

A last thought on density

Intensive property - is a physical property of matter that does not depend on the system size or the amount of material in the system

Examples: density, color hardness, melting point, boiling point

Extensive property – any property that depends on the size of the system. A property that changes as the amount of matter changes.

Examples: mass, volume, temperature, energy released/absorbed

Extensive & Intensive Properties

Temperature Discussion

State of matter: gas, liquid, solid

Kinetic Molecular Theory: A theory of the behavior of matter at the molecular level

Kinetic Energy: The energy of a moving object, dependent on its mass and velocity

K.E. = 1/2mv2

Classification of Matter

Solid - Liquid - Gas

Matter has both _______ and _________

Macroscopic –measurable and observable to the naked eye

Macroscopic properties - color, length

Submicroscopic or particulate –not measurable with a microscope

Particle size, chemical bond length

Matter at the Macroscopic and Particulate Levels

3 examples 2 forms of energy Is energy a form of matter

Matter Q’s

A. Measurement Systems – Definition and use of SI (metric) system

Metric: English:

B. Prefixes (see page 25 in textbook) also on white board

Measurement System – in summer work

C. Length base unit – meter

Conversions: 2.54 cm = 1 inch

Units of Measurement

D. Mass ◦ base unit – kilogram

Conversions: 453.5 g = 1 pound (only on earth!)

E. Time base unit – second

Conversions: 1 hour = 60 minutes; 1 minute= 60 seconds (NOTE THESE ARE EXACT

NUMBERS)

A value that is calculated from other measured values; not directly measured

◦ Volume – L x W x H

Derived units

G. A problem solving method

Definition: used to convert one or more units to other units

◦ Example: how many seconds in a day ??

◦ 1 day 24 hours 60 min 60 sec = 1 day 1 hour 1 min

Dimensional analysis, Unit conversion, Factor-Label method

2. Using Dimensional Analysis A. Express the quantity 1.00 ft in different

dimensions (inches, meters).

B. Conversion Factors 100 cm = 1m 454 g = 1 lb Exact and don’t impact significant figures

C. Example Problems Simple conversion: How many cm3 in 2.57

L?

Multiple conversion: How many inches are equal to 4.00km?

Combined Units: A speed of 80. km/hr is equivalent to how

many inches per minute?

Area conversions: 150.0km2 = ? mm2

Volume conversions: Convert 3.50 g/km3 to kg/m3

Accurate – close to the true value Precision – reproducibility of the

measurement

Percent Error:

Accuracy vs. Precision

Significant Figures: Why are they important? Numbers in math

Vs.

Numbers in chemistry

State the problem◦ Organize the information◦ Determine what you know & what you need to know

Determine the strategy◦ May stem from prior knowledge

Write down each step◦ NO WORK NO CREDIT!!

Check your answer◦ Is it reasonable????

Problem Solving

Chapter 1◦ Density p. 39 # 21, 23, 25, 55, 57◦ Unit Conversions p. 40 31, 33, 35, 37, 53, 59◦ Problem solving p. 40 45, 47, 49, 61, 63, 77◦ Dimensional Analysis Worksheets◦ Sig fig review worksheet

HOMEWORK ASSIGNMENTS