Q4- GEN CHEM Flashcards
A substance which speeds up a reaction but is chemically unchanged as it ends
Catalyst
The process of speeding up a reaction by using a catalyst
Catalysis
Types of catalyst
Homogeneous Catalyst, heterogeneous catalyst
When a catalyst and the reactants are in the same physical state or phase, the reaction is considered
Homogenously catalyzed/ homogeneous Catalyst
Additional info: this happens mostly with gaseous catalyst-reactant pairs.
When the catalyst and the reactant are in different phases, the reaction is said to be
Heterogeneously catalyzed
Additional info: common heterogeneous catalyst mostly include inorganic or a non carbon containing solid like elemental metals, sulfides and metallic salts.
proteins that function as catalyst in all living systems. They are natural catalysts found in the body.
Enzymes
They are responsible for many essential
Biochemical reactions
They have components called ______ binding sites or an active site, where molecules involved in a reaction under catalysis become attached
substrate
_____ ___ of Thermodynamics states that energy cannot be created or destroyed.
First Law
The _______ ___ of thermodynamics states that a spontaneous process will increase the ENTROPY of the universe.
second law
If the system becomes less ordered, the entropy________.
increases
If the system becomes more ordered, the entropy _________
decreases
Comparing entropies
The greater the number of possible microstates for a system, the higher the entropy. Microstate refers to the arrangement of the energy of each molecule in the whole system at one instant. It is directly related to the amount of the substance.
A. Number of Possible Microstates
Comparing entropies
Different phases have different entropies. Gases have higher entropy than liquids and liquids have higher entropy than solids.
B. Phases
the process of changing solid to liquid
Melting
the process of changing liquid to gas
Evaporation
the process of changing liquid to gas
Evaporation
the process of changing gas to liquid
Condensation
the process of changing liquid to solid
Freezing
Comparing entropies
The higher the temperature, the higher the entropy
C. Temperature
Comparing entropies
Compared to a pure substance, in which all particles are identical, the entropy of a mixture of two or more different particle types is greater. This is because of the additional orientations and interactions that are possible in a system comprised of nonidentical components
D. Mixture vs pure solvent
Comparing entropies.
When a solid dissolve in a liquid such as sodium chloride in water, the particles of the solid experience both a greater freedom of motion and additional interactions with the solvent particles. This corresponds to a more uniform dispersal of matter and energy. The process of dissolution therefore involves an increase in entropy.
E. Dissolved Substances vs. Precipitate
Comparing entropies.
The side of the equation with more moles of gas has a higher total entropy. This is because a greater number of moles indicates a greater number of gas particles and a greater number of arrangements of the gas particles.
F. Presence of gas
What formula is this?
∆S reaction= ∆Sproducts - ∆Sreactant
Formula of entropy
The symbol for entropy is
S
standard entropy of a substance is given by the symbol
S°
Standard entropy is the entropy of a substance at 25°C and 1 atm of pressure. The units for entropy are J/K mol
Read carefully 🐯
Generally, a reaction is said to occur _____________ if the entropy increases. Entropy (S) is a measure of the disorder in a system.
spontaneously
Are attractive forces BETWEEN molecules
Intermolecular forces
They are important because they determine some physical properties of molecules like boiling point, melting point, and density
Hold atoms together in a molecule
Intramolecular forces
Van der waals forces
Between polar molecules
Dipole-Dipole Interaction
Van der waals forces
Between polar and non polar molecules
Dipole-induced dipole interaction
Van der waals forces
Between non polar molecules
Dispersion forces
the relative tendency of an atom to attract electrons to itself when chemically combined with other atoms
Electronegativity Values
__________ of Molecules depends on:
Electronegativity (EN) Difference
Geometrical Shapes of Molecules
Polarity
Electronegativity Difference (ΔΕΝ) and
Type of Bonds
lonic Bond ≥ 1.7
Polar Covalent 0.5-1.6
Nonpolar Covalent ≤ 0.4
formed when electrons are shared unequally by two atoms in a compound, forming an electric dipole
Polar Covalent Bond
An atom with higher EN value becomes the partially negative pole
And with lower EN value becomes partially positive
Between ion and polar molecules
Ion-dipole interaction
Between polar molecules (H must be attracted to O, N or F or another molecule)
Hydrogen bond
the ability water has to flow upward against the force of gravity, due to cohesion and adhesion
Capillary Action
- Capillary Action
- sticking together of two like molecules
• Cohesion (cohesive)
-2 water molecules are cohesive due to the hydrogen bonds
- Capillary Action
- sticking together of two unlike molecules
• Adhesion (adhesive)
Ex: A water molecule being attracted to a sugar molecule (Like making Kool-aid)
Add: 1. Polarity
- a measure of the force necessary to stretch or break the surface of a liquid
Surface tension
- amount of heat that must be absorbed or lost before it actually changes temperature
Specific Heat
-The cooling of a surface occurs when the liquid evaporates
Heat of Vaporization
- a measure of how compact the atoms or molecules are within a substance or how much mass there is in a given space (volume)
Density
- a liquid that dissolves a particle (solute)
Solvent
- Universal Solvent
- particle or liquid that gets dissolved in the solvent
Solute
-A unique temperature and pressure at which three phases (usually solid, liquid, and gas) can exist together
Triple Point
The temperature and pressure at which gas and liquid merge together to form a supercritical fluid. Beyond this temperature, no amount of pressure will condense the gas to a liquid
Critical Point
At 1 atm pressure, the temperature at which the solid melts to liquid.
Normal Melting Point
At 1 atm pressure, the temperature at which the liquid vaporizes to become a gas
Normal Boiling Point
A measure of kinetic or translational energy
Heat
Measure of warmth and coldness
Temperature
■The _______ ______ is a graph which represents how a sample changes phases. As heat is added over time, the sample changes temperature and phase accordingly.
heating curve
It is a “map” that tells us which state(s) of matter (solid, liquid, gas) exist for a given set of temperature and pressure conditions.
Phase diagram
is the amount of energy needed to completely make a solid into a liquid
Heat fusion
is the amount of energy needed to completely make a liquid into a gas
Heat vaporation
A ratio comparing the amount of solute to the amount os solution
Concentration
A homogeneous mixture of one substance(the solute) dissolved in another substance (the solvent (
Solution
mass solute (g)/ mass solution (g) × 100
Percent mass
volume solute (ml)/volume solution (ml) × 100
Percent volume
Expresses the concentration of solution as the mass of solute in a given mass of solution
Ppm
Typically used for very small Concentration
Ppb
Moles • grams/1mole= grams
Mass to moles
An expression of moles/Liter of the solute
Molarity
Another quantitative expression of the concentration of the solution
Molality
The study of quantities of materials consumed and produced in chemical reactions.
Stoichiometry
The minimum energy required for a reaction to take place
Activation energy
The measure of how much exposed has which is expressed in square units
Surface area
Those that result in a chemical reaction and a new product is formed.
Effective Collisions
A collision is considered __________ when one doesn’t lead to product formation
Ineffective
