Chemistry 14A

Flashcards based on class notes and practice midterm samples/solutions

Karl Popper’s Theory

Scientific theories can only be proven incorrect; they can not be proven correct. The goal of science is to discard incorrect theories rather than confirm them.

Kuhnian Scheme (By Thomas Kuhn

Kuhn believes that there is a chaotic, pre-scientific stage followed by the establishment of a paradigm within which anomalies arise. When there is complete disagreement among members of a paradigm, a revolution forms to establish a new paradigm.

Law of Conservation of Mass

Mass is neither created nor destroyed. According to this law, the mass of products in a chemical reaction must equal the mass of the reactants: Mass of A + Mass of B = Mass AB

Law of Constant Composition

When two elements combine they will do so in the same proportion

Law of Multiple Proportion (Dalton)

If two elements combine and form more than one compound, the weights of one element that combine with a fixed weight of the other are in a ratio of small whole numbers

Hypothesis

An educated guess, or an untested explanation, that is based upon observations or known facts

Theory

When a hypothesis has been repeatedly tested and verified by other scientists, it may be accepted as a theory. Theories explain observations and laws.

Laws

Laws describe past observations and predict future observations but do not explain how they happen.

Physical change

The identity of the substance does not change, only its physical properties are different

Chemical change

When a substance is transformed into a different substance. Example: hydrogen changing to water

Physical properties

Characteristics that can be observed or measured without changing the identity of the substance. Example: mass, temperature, melting point, hardness, color, state of matter, and density

Chemical properties

The ability of a substance to be changed into another substance. Example: a chemical property of the gas hydrogen is that it reacts with oxygen to produce water

The power of ten that defines kilo-

10^3

The power of ten that defines centi-

10^-2

The power of ten that defines milli-

10^-3

The power of ten that defines micro-

10^-6

nano-

10^-9

Empirical Formula

Finding Maximum Height

h= v^2/2g

Kinetic Energy Formula

K=1/2mv^2