Chemistry Flashcards
what elements cannot exist alone?
hydrogen, nitrogen, oxygen, fluorine, chlorine, bromine, iodine and astatine
What is fractional distillation
Fractional distillation separates a mixture into a number of different parts, called fractions.
Fractional distillation is used to separate crude oil into fractions with different boiling points (industrially or in the laboratory), where the difference in boiling points is less than 1000C (more precise than simple distillation).
The majority of our fuels and plastics are derived from oil, thus demand is high.
How does fractional distillation work with crude oil
- Oil is heated to about 450°C and pumped into the bottom of a tall tower called a fractionating column, where it vaporizes.
- The column is very hot at the bottom but much cooler at the top. As the vaporized oil rises, it cools and condenses.
- Heavy fractions (containing large molecules) have a high boiling point and condense near the bottom of the column.
- Lighter fractions (containing small molecules) have a lower boiling point and condense further up the column.
Whats the thing abt boiling point
Smaller hydrocarbons have a lower boiling point, more volatile (evaporate quickly)
Easier to ignite, thus often used for fuels (demand is high)
Why? Because the intermolecular forces between large molecules are stronger than the intermolecular forces between small molecules.
More energy is needed to break the forces between large molecules, so the boiling point is higher!
What are the 3 types of hydrocarbons
Alkane - single bonds + saturated
Alkene - one double bond and the rest singles + unsaturated
Alkyne - one triple bond and the rest single + unsaturated
Whats the same of a hydrocarbon based on the no. of carbona?
Eth- 1
Meth- 2
Prop- 3
but- 4
pent- 5
hex- 6
hept- 7
oct- 8
non- 9
dec- 10
Why are ene + yne unsaturated?
Bc they have a double or triple bond iwth another carbon meaning that the H could bond with another element if it wants to
what chemical vs physical change
Physical Change changes the appearance or form of matter, not the kind of matter in the substance
Chemical change: changes the composition of the substances, with at least one new substance with new properties are formed
changes the chemical identity
what are the 5 types of chemical reaction?
Synthesis reaction
Decomposition reaction
Single displacement reaction
Double displacement reaction
Combustion reaction
what are some rules when predicting the product of a reaction
Cations always replace cations
Anions always replace anions.
You must use the criss-cross rule to ensure your formulas are correct!
What is the law of conservation of mass
The law of conservation of mass states that mass is conserved in a chemical reaction; the total mass of the products is always equal to the total mass of the reactants in a chemical reaction.
The idea that atoms are conserved (neither made nor destroyed) is believed to be true for all chemical reactions.
To test this, reactants will be placed in a flask where its contents will be measured before and after the chemical reaction.
Whats collisoin theory?
It states that for a reaction to happen, particles (atoms, ions, or molecules) must collide with each other under the right conditions.
What is needed to make collision theory happen
The particles have to collide in the right orientation (direction).
The particles have to collide with enough energy (activation energy).
Increasing the number of successful collisions between reactant particles will speed up a reaction
Increased temperature
Increased concentration of dissolved reactant particles (or increased pressure of gaseous reactants)
Increased surface area of solid reactants
Use of a catalyst
Whats activation energy
the minimum amount of energy required for reactant molecules to successfully collide and form products in a chemical reaction.
How does surface area effect rate of reaction
More surface area results in more collisions of the reactant molecules and an increased rate of the reaction.
If there is a large surface area, there is more surface for collisions to happen (more collisions per second)
For example: powdered sugar dissolves more quickly in water than a lump of sugar.
whats a catalyst
A catalyst is a substance that can alter the rate of a chemical reaction by lowering the activation energy.
A catalyst …
is not consumed in the reaction & doesn’t change the products
can provide a surface for reactions to take place on
Ensure reactant molecules are held at a favourable angle for collisions to occur (increasing likelihood of success)
are subjective in nature (i.e. certain reactions only)
What are the main differences between ionic and covalent compounds in relation to their conductivity?
Since covalent compounds are composed of neutral molecules, their electrical conductivity is generally quite poor, whether in the solid or liquid state. Ionic compounds do not conduct electricity in the solid state because of their rigid structure, but conduct well when either molten or dissolved into a solution.
What are the phase transitions?
solid - liquid = melting
liquid - gas = evaporation
gas - plasma = ionization
gas - liquid = condensation
liquid -solid = freezing
solid - gas = sublimation
gas - solid = depositition
plasma - gas = deionization
Whats the Four common physical properties of matter
Volume and Shape
Density
Compressibility
Thermal Expansion
Thermal Expansion is a measure of the change in volume (of a sample of matter) resulting from a temperature change
what are the 5 statements of kinetic molecular theory
- Matter is composed of tiny particles that have definite and characteristic sizes that do not change.
- The particles are in constant, random motion and therefore possess kinetic energy
- The particles interact with one another through attractions and repulsions, therefore possess potential energy (aka stored energy)
- The kinetic energy (velocity) of the particles increases as the temperature is increases
- The particles in a system transfer energy to each other through elastic collisions - kinetic energy remains constant, collisions bounce off one another and continue moving
whats kinetic energy
Kinetic Energy is energy that matter possesses because of particle motion.
An object that is in motion has the ability to transfer kinetic energy to another object upon collision with that object.
Whats thermal expansion
- as temperature increases, kinetic energy increases
- In Solids: as temperature increases, more vibrational motion occurs.
Therefore particles occupy larger volume and a slight expansion occurs
In Liquids: as temperature increases, particle velocity increases (rate and direction of an object’s movement) and more vibrational amplitudes (distance of movement from its original position to the extreme position) occur.
Therefore particles occupy larger volume.
In Gases: as temperature increases, particle velocity increases (rate and direction of an object’s movement).
Increased kinetic energy allows them to push back whatever barrier is confining them into a given volume, thus volume increases.
Therefore particles occupy larger volume.
Whats exothermic vs. endothermic
- Exothermic is a change of state in which heat energy is given off.
- example: freezing, condensation, deposition.
- This chemical reaction usually results in energy released as heat, so the surrounding get hotter.
For example: handwarmers - However, sometimes the energy is released as light instead of heat.
For example, glowsticks release light without increasing in temperature. - Endothermic is a change of state in which heat energy is absorbed.
example: melting, sublimation, evaporation. - Endothermic reactions absorb energy from the surroundings. This energy is usually absorbed as heat, so the surroundings get colder.
- Photosynthesis is an endothermic reaction because plant leaves absorb light energy.
- Thermal decomposition reactions are endothermic because they absorb energy when the chemicals are heated.
what is intermolecular force
Intermolecular forces are forces of attraction or repulsion which act between neighboring particles (atoms, molecules or ions)
