Random Mix (units 1 And 2) Flashcards
What are the three types of Van der Waals forces?
London Dispersion Forces
Hydrogen Bonding
Permanent-dipole interactions
What type of intermolecular interactions occur in Ammonia (NH3)
Hydrogen bonding
Why does the first ionisation energy decrease as a group is descended?
There are added electron shells which increase shielding and decrease attraction for electrons
Why are the intermolecular forces in carbon tetrachloride (CCl4) only London dispersion forces?
The molecule although containing polar bonds is symmetrical, hence its polarity cancels each other out.
Why does propan-1-ol have a lower boiling point than ethan1,2diol
Ethan1,2diol has two hydrogen bonds per molecule whilst propan-1-ol only has one
Which element would have the strongest metallic bonding; sodium, magnesium or calcium
Magnesium as it only has 3 electron shells (calcium has 4) and the outer shell contains 2 electrons per atom instead of the 1 in sodium (has greater nuclear charge)
In terms of collision theory, explain the effect of temperature on reaction rate
Greater proportion of reactant particles will have sufficient activation energy and the rate of collisions will increase due to particles moving faster
What effect does a catalyst have on a potential energy diagram?
Lowers the activation energy
In terms of bonds explain what is meant by an endothermic reaction
Product bonds can store more energy than reaction bonds
What does the activated complex look like for the following reaction
H2 + Cl2 -> 2HCl
H—-H
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Cl—Cl
What formula is used to calculate reaction rate
Change in conc/volume/mass
Over
Change in time
Name a compound in which the solid is less dense than the liquid
Water
A mixture of sodium sulphate and sodium phosphate contains 10 moles of sodium and 2 moles of phosphate ions. How many sulphate ions are present?
Na has a valency of 1, SO4 a valency of 2
2NaSO4 is sodium sulphate
The ratio is 2:1.
Na has a valency of 1, PO4 a valency of 3
3NaPO4 is sodium phosphate
Ratio is 3:1.
So if this has 2 moles of phosphate then there is 6 moles of sodium.
As there is 10 moles of sodium altogether then there is 4 moles of sodium in the sodium sulphate, meaning there is 2 moles of sulphate
Why is there a large jump between the second and third ionisation energies of of calcium?
The third electron is being removed from a very stable full electron she’ll arrangement
What is the equation for the 2nd ionisation enthalpy of Oxygen?
O+(g) —> O2+(g) + e
Name the reactants required to make ethylbutanoate
Ethanol and butanoic acid
Esters can be used as flavourings. What other use do esters have?
Solvents
What method is used to hydrolyse an ester?
Reflux
What type of reaction is used to make soap molecules?
Alkaline hydrolysis
What is the traditional name for propan-1,2,3-triol?
Glycerol
Which types of molecules have a tuning fork shape?
Fats and oils
What change in physical properties occur when a fat is dehydrogenated?
The melting point lowers and it turns into a liquid at room temperature (this is due to the formation of double bonds- making it more unsaturated)
What chemical process occurs in the manufacture of margarine
Hydrogenation
What is meant by hydrophobic
‘Water hating’
Amide link
C=O-N-H
What is the molecular formula of glycerol
C3H8O3
What part of a soap molecule is hydrophilic and hydrophobic
Ionic Hydrophilic head (dissolves in water, not oil)
Non polar hydrophobic tail (doesn’t dissolve in water, oil soluble)
What type of bonding holds alpha helixes together in proteins?
Hydrogen bonding
What is the pattern of oxidation in alcohols?
Primary and secondary alcohols can be oxidised
Tertiary cannot
Why is there a large jump in ionisation energy between the 2nd and third ionisation energies of magnesium?
The third electron is being removed from a very stable full electron arrangement
What is formed at the highest potential energy point in a reaction
Activated complex
Which factor is changed that allow particles to collide with greater energy?
Temperature
The relative rate of a reaction is found to be
0.002 s-1 How long was the reaction timed for ?
500 seconds
What is an activated complex?
An unstable intermediate structure formed by product bonds partially forming and reactant bonds partially breaking
What is eA used for
To form an activated complex
Why is energy absorbed in an end other,it reaction?
Because the products can store more energy than the reactants
What is the rate of reaction in the last 20 s before the reaction stops. Mass(g) 4 2 0.5 0.5 Time (s) 0 20 40 60
0.075gs-1
Which of the following could be a unit of measurement for a rate of reaction
0C\min, mg\0C, mg\hr
Mg/hr
What would prevent a collision by reactant particles which have the sufficient activation energy
Incorrect collision geometry
Explain the pattern of atomic size as a group is descended
Atomic size gets bigger as the number of shells increase decreasing attraction due to increased shielding effect
Explain the pattern of ionisation energy as a period is crossed
Ionisation energy increases as atomic number increases due to increasing attractive forces.
What is the intermolecular force of attraction found in oxygen gas
London dispersion forces
How are London dispersion forces caused
The transient displacement of moving electrons within the electron cloud causes slightly momentary dipoles
Why does phosphorous have a higher melting point than chlorine
Phosphorous is a larger molecule P4. Whilst Chlorine is diatomic. Hence larger London dispersion forces
