CHEM 100 Midterm: Chem 100 exam 1 study guide
CHEM 100 EXAM STUDY GUIDE
Chapter 1
Hydrophilic
➢Water-like
Homogeneous (a solution)
➢Ex: water + sugar
➢uniform
Heterogeneous
➢When something does not mix together and you can still see the compound
➢Not uniform
➢Ex: Sugar + gas
➢Gas = hydrocarbon
○Very hydrophobic
What are the 4 major categories of biomolecules?
➢Proteins
➢nucleic acids
○DNA is the biomolecule responsible for heredity
➢Lipids
➢carbohydrates
Scientific method
➢Quantitative (numbers)
2 types of pure substances
➢Elements
○Most basic building blocks
➢Compounds
○Formed by elements
○The ratio of elements is always the same
➢In most substances → solid has the highest density
○When is liquid more dense than a solid?
■Water (why ice floats!)
3rd Law of thermodynamics
➢Energy is conserved, never destroyed or formed
Scale
➢Deposition of Mg and Ca → tap water
Water
➢Bonds to itself by hydrogen bonds
Metric system
➢Modern metric system = SI
○kg, meter, second
➢1 m = 100 cm
➢1 cm = 1/100 m
➢Nano = 1 x 10−9
➢Micro = 1 x 10−6
➢Milli = x 101 −3
➢centi = 1 x 10−2
➢Kilo = 1 x 103
➢Mega = x 101 6
➢Giga = 1 10x9
➢Tera = 1 10x12
➢*1 in = 2.54 cm
➢*1gal = 3.785 L
➢*1 cm^3 = 1 mL
Pure substances
➢Can be obtained by separation methods
➢Unique physical and chemical properties
➢Usually in a container
Physical properties
➢Texture, color, odor, density, solubility, boiling/melting point
What physical property is used in distillation?
➢Variable boiling points
Physical properties used in 3 purification methods?
➢Variable affinities against solid support
➢Variable solubility
➢Variable boiling points
Chemical property
➢Substances lose their chemical identities and make new substances that have new
physical/chemical properties
➢Heat or light made is a chemical change
Significant figures
➢Accuracy of measurement
➢Last number in sig fig = has uncertainty
➢4 → 1 sig fig
➢4.0 → 2 sig figs
Document Summary
When something does not mix together and you can still see the compound. Dna is the biomolecule responsible for heredity. The ratio of elements is always the same. In most substances solid has the highest density. Energy is conserved, never destroyed or formed. Deposition of mg and ca tap water. Texture, color, odor, density, solubility, boiling/melting point. Substances lose their chemical identities and make new substances that have new physical/chemical properties. Heat or light made is a chemical change. Last number in sig fig = has uncertainty. Any number raised to power of zero is equal to 1. A zero in a number is significant. A zero before a number is not significant. A number that ends with 0 and has no decimal point, ex: 60, is ambiguous. Write it as a number between 1-10 multiplied by 10 raised to a whole number. 30 x 10^4 is not correct because 30 is not between 1-10.
