Chemistry Part 2

Matter

Pure substance can’t be separated to simpler substance by physical means (versus chemical means). Example: Water, Copper.

Mixtures: combo’s of 2 or more substances.  Example: Wine, cement, burritos.

Element:  Compound of only one type of atom.

Compound: Contains 2 or more types of atoms (H20, CO2, NaCl, CH4)

Phase: A region of matter with unique properties.

Homogenous: 1 phase.

Heterogenous: 2 phases or more.

A mixture can be homogenous or heterogenous while a pure substance can be an element or compound.

Energy: Capacity to perform work.  Not a physical thing.

Work: Moving an object a distance.

Kinetic Energy: 1/2 * Mass * Velocity^2

Potential Energy: m*g*h.

You can change form between PE and KE like a swing.

Solar: E=ho

Chemical energy is the energy of the bonds between atoms.

Nucleur energy are the bonds between nuclei of atoms.

Heat energy are the motion of atoms converted to heat or solar energy.

Temperature Scales

Temperature scales need 2 reference points and steps between them.  Boiling point and freezing point of water would be ideal.

Kelvin is based on the same increments as celsius and is created so only positive numbers exist to not screw up equations.  We could get to less than a millionth of a degree shy of absolute zero.  Fahrenheit was originally based on the freezing point of salt water and the high was based on the body temperature of the human body (~98).

• K = C + 273
• C = K – 273
• F = 1.8 * °C + 32

Specific heat

Specific heat is the energy required to raise a mass of an object by a certain degree.

Energy = m x Delta-T x C  [m=mass, Delta-T is change in T, C=specific heat]

Energy = 1 cal = energy to raise the temp of one gram of H2O by 1°C
1 kCal = 1 Cal = 1000 calories.

1 calorie = 4.184 Joules.