Reaction Rate + Organic Flashcards
What is a hydrocarbon
A molecule that contains carbon and hydrogen atoms only
Define a saturated hydrocarbon
Hydrocarbon with only single covalent bonds between carbon atoms
Why does one isomer have a higher melting point/boiling point
That isomer has a greater surface contact area. As a result, it will have stronger intermolecular dispersion forces, which means more energy is required to overcome them, and as a result a higher MP/BP
What are the requirements for geometric isomerisms
- Double bond between two carbons atoms (it is rigid so there is no free rotation about the carbon)
- Different groups on the carbon
Define homologous series
Groups of molecules that have the same functional groups, and as a result similar chemical properties. They also have the same general formula.
Define a fuctional group
The reacting part of a molecule responsible for the molecules chemical properties
What is meant by the term structural isomers
Same molecular formula, different structural formula as atoms are bonded in different order
Describe an addition reaction with bromine
It is a test for a double bond. Clear colourless gas bubbled through orange. solution. The solution turns colourless.
Requirements for addition reaction with hydrogen gas
Nickel catalyst, high temperature and high pressure
Property of reaction with hydrogen halides
Can produce isomeric produces. However, both the alkene and the reactant must both be non symmetrical, as if they can be placed in position x and y, or y or x, producing different products.
What are Arenes
Molecules that contain one ore more benzene rings, and only react in substitution reactions.
Requirement of substitution reaction of benzene
only takes place with a catalyst
Requirements for a reaction
- Particles must have sufficient energy (overcome activation energy)
- Collisions must occur
- Collisions must have the correct orientation
Difference between concentration and pressure
Concentration is used for solutions while solution is used for gas
Describe the effect of a catalyst in a reaction
A catalyst provides an alternative reaction pathway with lower activation energy. This increases the proportion of reactant particles particles with kinetic energy which matches or exceeds the activation energy, increasing the proportion of collisions that are successful, increasing the frequency of successful collisions. This increases the rate of reaction.
Describe the effect of increasing surface area.
Increasing the surface area provides an increased area for reactant particles to collide with, increasing the frequency of collisions, and as a result increases the frequency of successful collisions, increasing the rate of reaction.
Describe the effect of increase temperature
Increases the average kinetic energy of particles. This results in an increased velocity of particles, resulting in an increase in the frequency of collisions between reactant particles. Additionally, there is an increased proportion of collisions with sufficient kinetic energy to overcome activation energy leading to an increased proportion of collisions that are successful. These two factor leads to an increased frequency of successful collisions. As a result, there is an increased rate of reaction.
Describe the effect of increasing concentration.
Increases the number of reacting particles per volume, which increases the frequency of collisions. As a result, there is an increase in the frequency of successful collisions, increasing the rate of reaction.
Accuracy
How well measure/calculated value matches accepted value, increased with sound experiment process and increasing precision.
Validity
How well relevant controlled variables are maintained to ensure independent variable links directly to dependent variable without external factor influence. Increase validity by maintaining relevant controlled varables
Reliability
How close results are to each other
Increased by increasing the number of trails and reducing human error
Precisions
Precision is how close measured/calculated values are to one another. Increased using finely calibrated instruments and digital instruments.
Conclusion
Did results support hypothesis?
Refer to research and explain the trend
Evaluation
Talk about errors in measurement to do with procedure and equipment
Accuracy affected by systematic
Precision affected by random
if there is systematic error with equipment recalibrate
systematic
error of measurement that skews results
Describe the nature of bonding in alkanes, alkenes and benzene, using ideas of single and multiple bonds (π bonds), and delocalisation.
Sources
Alkanes contain only single bonds between carbon atoms. The carbons are sp3 hybridized and there is free rotation around the single bonds
Alkenes contain at least one carbon-carbon double bond. The atoms in the bond are sp2 hybridized and the double bond consists of one sigma and one pi bond.
The pi bond is formed by head on overlap of sp2 hybrid orbitals and the electrons are delocalized.
Benzene is a planar ring of six sp2 hybridized carbon atoms.
Each carbon forms three sigma bonds. The remaining p orbital on each carbon overlaps with neighboring p orbitals creating and delocalized pi bond system above and below the ring, where delocalized electrons are spread evenly around the ring.
Explain why trans-2,3-dichloro-2-ene(A) is a liquid when butane(B) is a gas
Boiling point of A is greater than the boiling point of B. This is because A has both dispersion and dipole-dipole forces whilst B has only dispersion. As a result, the cumulative strength of IMF of A is greater than B. Hence a greater amount of energy is required to overcome the IMF in A compared to B, hence a higher BP.