Exam 2

What becomes a source of energy?
Heat
Heat is the source of what?
Energy
What do we use to supply the energy we need?
Chemical reactions.
What do chemical reactions supply?
Energy
What is 1 cal?
The amount of heat needed to raise the temperature of 1 g of water by 1C
What is the amount of heat needed to raise the temperature of 1 g of water by 1C?
1 cal
Exothermic reactions…?
Produce heat.
Endothermic reactions…?
Absorb heat energy from surroundings.
What type of reaction absorbs heat energy from surroundings?
Endothermic.
What type of reaction produces heat?
Exothermic.
Carbohydrates provide…?
4 kcal/g (4 Cal/g)
Proteins provide…?
4 kcal/g (4 Cal/g)
Fats provide…?
9 kcal/g (9 Cal/g)
What is the rate of a reaction?
The amount of products formed from reactants in a given period of time.
What is the collision theory?
Views the rate of a reaction as the result of particles colliding with certain frequency and minimum energy.
Views the rate of a reaction as the result of particles colliding with certain frequency and minimum energy.
Collision theory
What must reactants do for a reaction to occur?
Must collide, collide with proper orientation, and collide with sufficient energy.
In an exothermic reaction who has the lower energy?
Products are lower energy than the reactants.
in an endothermic reaction who has the lower energy?
In an endothermic reaction the reactants are lower energy than products.
What are factors that affect reaction rates?
Concentration, temperature, or presence of a catalyst.
What effect does concentration have on reaction rates.
More reactants = more collisions.
What effect does temperature have on reaction rates?
Higher speeds = more collisions.
What does the coefficient in a reaction equation stand for?
The number of molecultes (mols)
Define equilibrium.
The rate of the reactants to products is the same as the rate of products to reactants.
What is the equilibrium constant?
K = (products)/(reactants)
K = (products)/(reactants)
Equilibrium constant
Preferred bonding pattern for H.
H-
Preferred bonding patterns for C
l
-C-
l

>C=

=C=

-C(tri)C-

Preferred bonding patterns for N
..
-N –
l

..
– N –
l

:N(tri)

Preferred bonding patterns for O
..
-O –

..
O =

Preferred bonding patterns for S
..
– S-
What is the VSEPR Theory?
Electron charge clouds will arrange themselves to be as far away from each other as possible.
What is electronegativity?
The ability of an atom to attract bonding electrons of a covalent bond to itself.
0 < 0.4 electronegativity
Nonpolar
Nonpolar bond in electronegativity
0 < 0.4
0.4 >
Polar
Polar bond in electronegativity
0.4 >
if the central atom has one or more pairs of nonbonding electrons, the molecule is…?
Polar.
If the central atom has no nonbonding pairs of electrons and all other atoms connected to the central atom are identical, the molecule is…?
Nonpolar.
If the central atom has no nonbonding pairs of electrons and at least one of the atoms connected to the central atom is different from the others, the molecule is…?
Polar.
Chromium ions
Cr(2+ or 3+)
Manganese ions
Mn 2+
Iron ions
Fe 2+ or 3+
Nickel ions
Ni 2+
Copper ions
Cu 1+ or 2+
Zinc ions
Zn 2+
A combination reaction is?
Elements or simple compounds that react to make a more complicated compound.
Elements or simple compounds that react to make a more complicated compound.
Combination reaction
Reactant is split into simpler compounds.
Decomposition.
A reaction with oxygen
Combustion.
Decomposition
Reactant is split into simpler compounds.
Combustion
A reaction with oxygen.
Single Replacement reaction
One atom replaces another atom in a second compound (cation with cation).
One atom replaces another atom in a second compound (cation with cation).
Single replacement reaction
What are the diatomic elements?
H2, N2, F2, O2, I2, Cl2, Br2
Double Replacement reaciton
Positive ions switch places when two ionic compounds react.
Positive ions switch places when two ionic compounds react.
Double Replacement.
What do saturated hydrocarbons contain?
Only carbon-carbon single bonds.
Simple organic compound names.
Meth, eth, prop, but, pent, hex, hept, oct, non, dec.
What are structural isomers?
Compounds with same molecular formula, but different connectivity.
Compounds with same molecular formula but different connectivity.
Structural isomer.
Stereoisomers are…?
Compounds which differ from each other by their arrange of atoms in space.
Compounds which differ from each other by their arrange of atoms in space.
Stereoisomers.
What are responsible for the spearmint and caraway seed flavor?
A pair of stereoisomerrs called carvones that are taste buds can distinguish between them
Difference between spearmint and caraway is…
The stereoisomers are identical except for the arrangement of groups in space.
Enantiomers are…
Mirror images, but cannot be simply flipped because of 3-dimensionality.
Mirror images, but cannot be simply flipped because of 3-dimensionality.
Enantiomers.
What is a chiral center?
A tetrahedral carbon bonded to four different atoms or groups of atoms. Molecules with a chiral center form mirror images that are nonsuperimposable.
What are intermolecular forces?
The attractive forces between molecules.
What are the attractive forces between molecules called?
Intermolecular forces.
What is weaker: intermolecular forces or covalent bonds?
Intermolecular forces.
What is the weakest of the forces?
London (dispersion forces)
When do london forces occur?
Momentarily in all molecules when electrons become unevenly distributed over a molecule’s surface.
What is created in london forces?
An induced dipole.
Where are london forces significant in?
Nonpolar molecules.
When is a permanent dipole created?
Only in polar molecules.
What must be always done in when comparing intermolecular forces?
Comparing molecules of similar molecular weight.
When do dipole-dipole attractions occur?
Between the dipoles of two polar molecules.
What is hydrogen bonding?
Interaction between two molecules, a donor and an acceptor.
What is the hydrogen donor?
A molecule with a hydrogen atom covalently bonded to an O, N or F
What is the hydrogen acceptor?
A molecule with a nonbonding pair of electrons on an O, N or F
A molecule with a nonbonding pair of electrons on an O, N or F
Hydrogen acceptor
A molecule with a hydrogen atom covalently bonded to an O, N or F
Hydrogen donor
What is the strongest of the intermolecular forces?
Hydrogen bonding.
When is something soluble?
Like dissolves like, soluble if the molecules can bond.
What is the golden rule of solubility?
Molecules that have similar polarity and participate in the same types of intermolecular forces will dissolve each other.
Molecules that have similar polarity and participate in the same types of intermolecular forces will dissolve each other.
What is the golden rule of solubility?
Can there be cis-trans in single bonds?
No.
What can have cis-trans?
Ring structures and double bonds.
AB2
Linear
Linear
AB2
AB3
Trigonal planar
Ab2N
Bent
Bent
Ab2N
Trigonal planar
AB3
Ab4
Tetrahedral
Tetrahedral
Ab4
Ab3N
Pyramidal
Pyramidal
Ab3N
Ab2N2
Bent