Change in measurable Change in time 0.2 – 0.05 = 0.15 0.15/20 = 0.0075mol l -1 s -1.
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Transcript of Change in measurable Change in time 0.2 – 0.05 = 0.15 0.15/20 = 0.0075mol l -1 s -1.
Draw a line to show the effect of an increase in temp
In some reactions - apart from heat energy, what other source of energy can be used to increase the number of particles over EA?
Draw a line to show the effect of an increase in temp
In some reactions - apart from heat energy, what other source of energy can be used to increase the number of particles over EA? Give them a hint “photosynthesis”. Answer : LIGHT ENERGY
Catalysts
• What types of catalysts do you get and explain what their names mean?
• Heterogeneous (different physical state)• Homogeneous (same physical state)
Catalysts• How do heterogeneous catalysts work?
• Reactant molecules adsorb onto the active site of the catalyst.
• Bonds between atoms within the reactant molecules weaken.
• New bonds form between atoms of the product.• Product desorbs from active site.• Active site free for new reactant molecules
Catalyst
Active site
Catalysts• What is the catalyst in a catalytic convertor?• What type of petrol must be used in a car fitted
with a catalytic convertor? Why?
• Transition metals (platinum, rhodium and palladium)
• Unleaded petrol, because the lead would poison the active sites on the catalyst.
• Poisoned active sites cannot adsorb new reactants
Ionisation energy decreases. The electron being removed is in an energy level further away from the nucleus AND there is a shielding effect from
the inner electrons.
The covalent radius decreases due to increased nuclear charge having a greater pull on the
electrons.
Name the types of bonding:electrostatic force of attraction between..
• positively charged ions and delocalised electrons
• positively charged nuclei and negatively charged shared electrons
• oppositely charged ions
Name the types of bonding:electrostatic force of attraction between.. • positively charged ions and delocalised
electrons– metallic
• positively charged nuclei and negatively charged shared electrons– covalent
• oppositely charged ions– ionic
Give examples of elements with
• Monatomic structure
• Covalent molecular structure
• Covalent network structure
• Metallic
Give examples of elements with
• Monatomic structure– He, Ar, Kr, Xe, Rn
• Covalent molecular structure– S, P and C (fullerene)
• Covalent network structure– B, C, Si (carbon – graphite and diamond)
• Metallic– Fe, Cu…any metal
• Why can metals and graphite conduct electricity?– Because they have delocalised electrons.
• Describe the structure of a fullerene.– A large spherical shaped carbon molecule
•Due to the presence of hydrogen bonds.•These relatively strong INTERMOLECULAR bonds mean molecules require more energy to become gaseous.•They arise between molecules which have H bonded to N,O and F
4 moles
1 mole of molecules X 5 = 5 moles of atoms
0.5 moles of molecules X 2 = 1 mole of atoms
1 mole of molecules X 4 = 4 moles of atoms
0.5 mole of atoms
Which one / ones will have the greatest volume?
4 moles
1 mole of molecules X 5 = 5 moles of atoms
0.5 moles of molecules X 2 = 1 mole of atoms
1 mole of molecules X 4 = 4 moles of atoms
0.5 mole of atoms
Which one / ones will have the greatest volume?
•Melting point increases.(Increased mass results in increased Van der Waals’ forces. Thus more energy is required for atoms to become gaseous.)
What type of bonds are present in these molecules?
What type of molecules are these?Which one could be used as a solvent for
hexane (a non polar molecule)?
CCl4 –non polar molecule(perfect symmetry)
CCl4 could be used as a solvent for hexane (a non polar molecule)?
CHCl4 –polar molecule(doesn’t have perfect symmetry)
ALL of the bonds are polar since the atoms all have different electronegativities.
• Van der Waals’ forces are a result of electrostatic attraction between temporary dipoles and induced dipoles caused by movement of electrons in atoms and molecules.