Section D Flashcards
Dalton’s Atomic Theory
All matter is made up of atoms
Atoms of a specific element are identical to each other, but different from atoms of any other elements
Compounds are combinations of atoms of two or more different elements
In chemical reactions, atoms are combined, separated or rearranged
They are never created or destroyed
IONS
An atom containing an equal number of protons and electrons is electrically neutral
Gain of electron —— convert the atom to a negative ion – known as Anion
Loss of electron —— convert the atom to a positive ion – known as Cation
Positively charged ion – usually metals
Negatively charged ion – usually nonmetals
( ionization)
An atom gain or loose electrons to create a stable outer valence shell
Ionic Bond
An ionic bond is a chemical bond that involves a metal and a nonmetal ion
Atoms either losing or gaining negatively charged electrons, reacting to form ions
Positive ions (metals) are attracted to negative ions (nonmetals)
In naming simple ionic compounds, the metal (cation) is always first, the nonmetal (anion) second
Flint glass (soda lime):
Inexpensive, low resistance to heat and chemicals. Used to make disposable test tubes
Borosilicate glass:
Nonreactive with most chemicals, high thermal (heat) resistance glassware
Used for most lab glassware
Quartz/Silica glass:
Very expensive, contains only silica quartz with excellent optical qualities
Used for high precision work – spectrophotometry cuvettes, microscope lens
Volumetric pipette
Used for critical/accurate measurements
Calibrated to deliver “TD” a single volume
Has a bulged out portion (bulb) in the middle
Serological/Graduated pipette
Calibration marks to the tip
Etched ring around the top – last drop must be blown out
Mainly used for preparing serial dilutions
Transfer total capacity or partial volumes
Mohr pipette
Not calibrated to the tip
Do not drain beyond last calibration marking
Acids
Substance that release hydrogen ion (H+) as the only cations, when dissolved in water/aqueous solution
(loss of protons / proton donors)
When using acid and water, acid is slowly added to water
Bases
Substances that produce hydroxide ions (OH-) when dissolved in water
Salts
ionic compounds composed of cations and anions with an electrically neutral product
An acid and a base react to form a salt
Electrolytes
Solution that carries (conducts) electricity
Acids, bases, and salts form electrolytes because they produce ions when dissolved in H2O
Ions act as moving electrical charges and carry electricity
Electrodes
electrode is an electric conductor / cell that is referred to as either an anode or a cathode
Opposites attract Anode is (usually) positive Cathode is (usually) negative
Non Electrolytes (Sugars)
Do not produce ions
Dissolve as molecules
Do not conduct electricity
pH
pH is a measure of the acidity or alkalinity/basicity of a solution
A measurement of hydrogen ions in solution
(Mathematically) pH is the negative logarithm of the activity of hydrogen ions concentration
alkaline is basic
Low pH many H+ —> acidic solution
High pH few H+ —> basic solution
A pH decrease of 1 indicates that the solution is 10 times more acidic.
pH of Body Fluids
gastric juices 1.0 – 2.0 (strong acid)
blood 7.35 - 7.45 (weak base)
bile 7.8 - 8.6 (weak base)
urine 4.5 – 8.0 (weak acid
Buffer Solution
A solution that will maintain a constant pH when a small amount of acid or base is added to it
It is composed of a mixture of a weak acid or base and a salt of the acid or base
When acid is added, a buffer will absorb H + using the salt portion
When a base is added, a buffer will release H+ from the acid portion; this will neutralize the OH-
Analytic Reagent (AR)
ultra pure - used for clinical analysis
Pharmaceuticals:
Tested for toxic substance United States Pharmacopeia (USP) National Formulary (NF) Canadian Pharmaceutical (CP) Used to manufacture drugs Can be used in most clinical lab
American Chemical Society (ACS)
- high standard of purity
HPLC water – Solvents manufactured specifically for use with HPLC instruments. Meet all ACS specifications. Submicron filtered
Technical/Commercial grade
low purity Never used in chemical labs
Lab Grade
used in educational labs
Concentration
the amount of solute per unit of solution/solvent
Molarity (M)
Number of moles of solute per liter (1000 mL) of solution
A mole is the gram molecular weight of an element or a compound
Moles/liter (mol/L)
Normality (N)
one gram equivalent of a solute per liter of solution
Colloids:
Mixture in which one substance is divided into minute particles
Tiny particles suspended in a liquid
Colloids do not pass through membranes and will not settle
Examples of colloids –
Fog, smoke, homogenized milk