Chem P1 Flashcards
What is a standard solution?
A solution of known, accurate concentration.
What are the drawbacks/ issues with chlorinating drinking water
- Chlorine is toxic
- Forms halogenated hydrocarbons
- Forms carcinogens/ toxic compounds.
What is disproportionation?
A reaction where an ELEMENT is both oxidised and reduced.
Why does group 1/2 reactivity increase down the group
All normal points e.g. increased radius, shielding, decreased attraction etc.
Final point: therefore ionisation energy decreases!
How can gibbs free energy be written in a linear graph form?
Can be written in form y=mx+c
y= Delta G
m= - Delta S
x= Temp
c= Delta H
What always needs to be included in question on entropy change?
Talk about DISORDER- Higher in the products or the reactants?
When proposing a two step mechanism, which step needs to come first?
The SLOW step (RDS)
How do you calculate the “percentage dissociation” of a weak acid?
[H+]/[HA] x100
What do you need to watch out for when arrhenius equation is plotted on a graph?
Units/ scale e.g. ( x10^-3)
What is the general form of a two step mechanism?
Slow: Reactants in rate equation –> Intermediate
Fast: Intermediate + Reactants not in rate equation –> Products.
What’s the answer when asked what block an element is in
Example: Sodium
Answer: The block AND the subshell which the highest energy electron is in.
E.g. Sodium is in S block, it’s highest energy electron is in 3S2
How does pH of Grp 2 Hydroxides change as you go DOWN group 2
The pH Increases (becomes more alkali)
State (again) and explain the change in pH of metal hydroxides down Grp 2
pH increases (becomes more alkali) because :
* They become more soluble as you go down the group.
* This is explained by decrease in lattice enthalpy of the hydroxide salt, and increase in coordination number of the metal ion.
How does Oxygen bind to haemoglobin?
O2 gas can bind with Fe2+ ion found in the middle of haem groups.
This forms oxyhaemoglobin
What can also bind to haemoglobin?
Carbon dioxide (CO2) and Carbon monoxide (CO)
What happens when CO is breathed in?
Ligand substitution reaction takes place O2 in Hb is replaced by CO
Why is CO Dangerous?
CO binds very strongly with Hb, more strongly than O2 so prevents O2 from binding.
Bond is so strong that it is irreversible.
Too high levels of carboxyhaemoglobin can lead to death.
In a titration, why may just a small concentration be used?
So that the titre volume increases, which leads to a lower percentage uncertainty.
What is the difference of BPs between HBr and HI a result of and why?
Stronger Induced dipole-dipole interactions (London forces), due to a difference in size and so a difference in no. of electrons.
What do you need to remember to do when Making up a 250cm^3 standard solution.
- When you are transferring solution from beaker to volumetric flask, ensure to rinse the sides of the beaker into the flask so no solution remains in the beaker.
- When you are making the solution up to the 250cm^3 mark, invert several times to ensure solution is thorougly mixed.
What is the structure of cisplatin
When given a reaction equation and a value of k with units, how can you work out the overall order of the reaction?
Using the units of k to work it out. (work backwards)
What is “weighted mean mass”
The mean mass taking into account the relative abundance of the isotopes
When trying to work out the order of reaction with respect to a reactant, why may a large excess of the other reactant be used?
- To keep the concentration of the other reactant constant.
- So the reaction is 0 order wrt the other reactant
- To ensure equilibrium is far to the right
Benefit of using chlorine in water treatment
Kills bacteria/ microorganisms
What happens when HCl is added to AgNO3(aq)?
White precipitate forms
What is the structure of silicon
Giant covalent lattice
Does not contain intermolecular forces
Why is second ionisation of an element greater than first ionisation energy?
- When first electron is removed, cation forms
- Second electron removed from cation, greater nuclear attraction between cation and outer electrons
In exothermic reaction, with fewer gas mol on RHS. Why is it difficult to predict how the changes affect the amount of product formed?
Increased temp, increased pressure:
Temp shifts Eq left, Pressure right.
It is difficult to determine the relative contributions of the two opposing factors
Why do strong acids react quicker than weak acids?
- In strong acids, there is greater [H+]–> therefore more frequent collisions, therefore faster rate of reaction.
Monobasic acid
One mole of acid dissociates to form one mole of H+
Colour change at end point of MnO4-/Mn2+ titration.
Colourless –> Pale purple
What colour is methyl orange at end point
Orange
What colour is methyl orange when acid
Red
What colour is methyl orange when conjugate base
Yellow
What pH range does methyl orange work over
Acidic- roughly 3-4 pH
Colour change of phenolphthalein
Colourless- pink
