Unit 5 chemistry Flashcards
How do you convert from oc to K?
Add 273
What is enthalpy?
the total heat content of a system
what are the standard conditions needed for enthalpy?
pressure of 100kPa, temperature of 298K (250C) and for Reactants and products to be in physical states.
What is the symbol for standard conditions?
ɵ
What are the units for enthalpy change?
Joules per mole
What is meant by system?
a set of things working together as parts of a mechanism
What is meant by surroundings?
the things and conditions around a certain item.
What is the enthalpy change of formation definition?
When one mole of a substance is formed from its original elements in their standard state under standard conditions
What is the enthalpy change of hydration definition?
The energy released when one mole of gaseous ions are dissolved in water under standard conditions
What is the enthalpy change of combustion definition?
When one mole of a substance is burned completely in oxygen under standard conditions
What is the enthalpy change of reaction definition?
Energy change when reactants form products in molar quantities under standard conditions
When the reaction is exothermic, is the energy change positive or negative?
Negative
When the reaction is endothermic, is the energy change positive or negative?
Positive
What is a hydrocarbon?
A compound made up of just hydrogen and carbon atoms
What is the general formula for an alkane?
Cn H2n+2
What is the general formula for alkenes?
Cn H2n
What are the names of the first 6 alkanes?
Methane, Ethane, Propane, Butane, Pentane, Hexane
What are the prefixes for branched alkanes with a chain length of 1 - 4 carbons?
Methyl, Ethyl, Propyl, Butyl
What is a structural isomer?
A compound that has the same molecular formula but a different structural formula.
What is a cycloalkane?
a hydrocarbon with a molecule containing a ring of carbon atoms joined by single bonds.
Why does the boiling and melting point of alkanes increase with chain length?
- As the carbon chain gets longer, there are more electrons in a molecule.
- There are more stronger intermolecular forces between the molecules.
- it takes more energy to break these forces
What are the names of the first 6 alkenes?
- Ethene
- Propene
- Butene
- Pentene
- Hexene
What is a stereoisomer?
each of two or more compounds differing only in the spatial arrangement of their atoms.
What is a symmetrical alkene?
in whose molecule the doubly bonded carbons bear the same ligands.
How do you test for an alkene?
A simple test with bromine water
What is a saturated hydrocarbon?
that contain only single bonds between carbon atoms.
What is a unsaturated hydrocarbon?
that have double or triple covalent bonds between adjacent carbon atoms
Describe sigma bonds.
the strongest type of covalent chemical bond. They are formed by head-on overlapping between atomic orbitals.
Describe pi bonds.
Covalent chemical bonds where two lobes of an orbital overlap two lobes of an orbital on another atom and this overlap occurs laterally.
What is electron pair repulsion theory?
to predict the geometry of individual molecules from the number of electron pairs surrounding their central atoms.
What are the bond angles for 4 bonding electron pairs, 3 bonding electron pairs and 2 bonding electron pairs?
2- 180 degrees
3- 120 degrees
4- 109.5 degrees
Which bond is stronger: sigma or pi bonds?
Sigma bond
which bond is stronger: single or double bonds?
Double bond
What is the word equation for the combustion reaction (complete)?
Fuel + Oxygen → Carbon dioxide + water
What is the word equation for the combustion reaction (incomplete)?
Fuel + Oxygen → Carbon monoxide + water + carbon
Why is combustion of fuels important?
The energy that the reaction produces can be used to heat water, cook food, generate electricity or even power vehicles.
What are the conditions for halogenation?
Uv light and heat
What is homolytic fission.
chemical bond dissociation of a molecular bond by a process where each of the fragments gains one of the originally bonded electrons.
What is a free radical?
an uncharged molecule (typically highly reactive and short-lived) having an unpaired electron.
What are the three steps of a free radical substitution reaction and state what happens in each step.
- Initiation- creates a radical species.
- Propagation- Once a reactive free radical is generated, it can form new free radicals.
- Termination- two free radical species react with each other to form a stable, non-radical adduct.
What factors affect the standard enthalpy change of hydration?
- Charge on the ion
- Size of the ion
What is the equation for calculating the standard enthalpy of a reaction?
Sum of standard enthalpy of products- Sum of standard enthalpy of reactants
What is the equation for calculating the standard enthalpy of a formation?
Sum of standard enthalpy of elements- Sum of standard enthalpy of compound
What are the 5 stages of the bayer process?
- Crush the Bauxite
- Removal of any impurities
- filter out solid impurities
- Allow it to crystalise to Al (OH)3
- Heat it in a rotary kiln to form Alumia
What are the 2 stages of the Kroll process?
1- Titanium oxide, coke and chlorine are heated together at 900 degrees to form titanium chloride
2- Magnesium is used as a reducing agent to form titanium
What are the raw materials for the contact process?
Sulfur + air + water
In a diaphragm cell, what metal is the anode made out of?
Titanium
In a diaphragm cell, what metal is the cathode made out of?
Steel
In a diaphragm cell, what is produced at the cathode
brine containing sodium hydroxide + hydrogen gas
In a diaphragm cell, what is produced at the anode
Chlorine gas
In a membrane cell,what metal is the anode made out of?
titanium
In a membrane cell,what metal is the cathode made out of?
nickel
