AS: Unit 2 Flashcards
Define “ACTIVATION ENERGY”
the MINIMUM energy required for a reaction to start and for successful collision
Define “Mean Bond Energy”
the ENTHALPY needed to BREAK the COVALENT bond into gaseous atoms, AVERAGED OVER diff. molecules
State “Hess’s Law”
the enthalpy change in a reaction is INDEPENDENT of the ROUTE by which the CHEMICAL CHANGE takes place
Standard Enthalpy of COMBUSTION?
ENTHALPY CHANGE when 1 mole of a substance is COMPLETELY COMBUSTED in EXCESS OXYGEN under STANDARD CONDITIONS. All Reactants and Products in their STANDARD STATES
Define “Enthalpy Change”
the HEAT ENERGY transferred in a REACTION @ CONSTANT pressure
Define “Standard Enthalpy of FORMATION”
also, give the Unit
the ENTHALPY CHANGE when 1 mole of a substance is FORMED from its constituent ELEMENTS; all Reactants and Products in their STANDARD STATES
• kJmol -1 •
What does a Catalyst do?
⬆️ the rate of reaction
- without getting used up
- by by providing an alternative reaction pathway
- with a ⬇️ ACTIVATION ENERGY
Why does a CATALYST have NO EFFECT on the POSITION of the EQUILIBRIUM?
cos it SPEEDS up the rates of the FORWARD and BACKWARD reaction by the SAME AMOUNT
Define “CARBON NEUTRAL”
an activity that has NO NET ANNUAL CARBON emissions to the ATMOSPHERE
Advantages of RECYCLING METALS?
- Saves RAW ? materials, finite
- Saves energy ? recycling takes less energy than extracting metal
- Reduces waste ? sent to landfill
- Mining damages landscape and spoil heaps are UGLAAAAAAAY
Disadvantages of RECYCLING METALS:
- Collecting and sorting metals from waste is difficult and expensive ?
- PURITY ? of recycled metals VARY as there’s usually other metals and impurities mixed in
- RECYCLING METALS MAY NOT PRODUCE A CONSISTENT SUPPLY TO MEET DEMAND ?
General Equation for NUCLEOPHILIC SUBSTITUTION?
R-X + OH- ➡️ ROH + X-
Bromine water to test for ALKENES, what type of reaction is this?
ELECTROPHILIC ADDITION
forms dibromoalkane
Alkenes + WATER and a h2so4 CATALYST makes…?
ALCOHOL ?
ELECTROPHILIC ADDITION
How are POLYMERS formed?
Give reaction’s name
The DOUBLE = BONDS in ALKENES open up and JOIN TOGETHER ??
ADDITION POLYMERISATION
- poly(ethene)
