Chemistry for Engineering

Are variables that we can measure without changing the identy of the substance being observed.

• Is a ratio of mass to volume, sometimes called mass density.
• To determine density, both mass and volume must be measure.
• Density is a physical property, physical property include color, viscosity, hardness and tempture.

• Indicates how close the observed value is to the "true" value.
• Dartboard analagy

Are unimaginably small particles that cannot be made any smaller and still behave like a chemical system.

Things we can see with the naked eye

Where we focus on the smallest components of a system. "Micro" Microscope.

The ability to communicate macroscopic and microscopic concepts efficiently

The ability to switch perspectives, to look at problems involving chemistry in several ways. The things we can seee about substances and their reactions provide the Macroscopic perspective. We need to interpret these events considering the Microscopic perspective, where we focus on the smallest components of the system. Finally, we need to be able to communicate these concepts efficiently, hence Symbolic.

• They are associated with the types of chemical changes that a substance undergoes.
• i.e. some materials burn readily, whereas others do not.

Cumbustion

• Is a measure of a material's ability to be rolled or hammered into thin sheets.
• FYI, Metals are valuable in part because of their malleability. (Same metal different shape)

Solids, liquids, and gases.

Elements

Are groups of atoms held together so that they form a unit whose identity is distinguishable differnt from the atams alone.

• Is the spread in values obtained from the measurement.
• A precise observatin has several measurements close in value.
• Dart board analagy

• Dart board illistration.
• Darts spread all over the dart board is bad precision and bad accuracy.
• Darts not on the bullseye is good precision but poor accuracy.
• Darts on the bullseye and all together is good precision and good accuracy.

Random Error is fundamental to any measurement. Random error may make the measurement either too high or too low and is associated with the limitations of the equipment with which the measurement is made.

• Makes measurements consistently either too high or too low. This type of error is often associated with the existence of some unknown bias in the measurement apparatus.
• i.e impurities in metals

Begins with a series of specific observations and attempts to generalize to a larger, more universal conclusion.

We have asserted that all gases expand to occupy the full volumes of their containers. This universal conclusion was first drawn by the inductive reasoning based on observations of many different gasses under many different conditions.

Takes two or more statements or assertions and combines them so that a clear and irrefutable conclusion can be drawn.

"if A and B, then C"

Usually, refers to a largely empirical description, such as the fact that gas pressure is proportional to temperature.

Most often refers to an explanation that is grounded in some more fundamental principle or assumption about the behavior of a system.

(as in relation to "model")

_{In popular culture, saying that something is just a theory indicates uncertainty. In science, a theory has significant credibility gained by many observations that confirm its validity.}

Laws

"Systeme International d'Unites or SI" carefully defined units are combines with a set of prefixes that designate powers of ten.