Paper 1 past paper questions Flashcards
Describe the structure and bonding in magnesium
There is a giant lattice of cations with electrostatic forces of attraction between cations with delocalised electrons
What’s is the formula for reacting magnesium with steam
Mg(s) + H2O(g) → MgO(s) + H2(g)
What’s are some observations for reacting steam with magnesium
A white flame and a grey powder is formed
What’s the least soluble group 2 metal and what is it used for
- Ba(SO4)
- Barium meals for x rays
What is electron impact
The sample being analysed is vaporised and then high energy electrons are fired at it. This usually knocks off one electron from each particle forming a 1+ ion
What atoms can be separated with electrolysis
Atoms above carbon in the reactivity series
What atoms aren’t separated with electrolysis
Atoms below carbon but above hydrogen in the reactivity series as they can be displaced by carbon instead
What are native metals
Metals below hydrogen in the reactivity series and found in their pure metallic form
What is the test for reactivity for metals
- Look at the covered in oil
- Observe them in air as some react with oxygen
- observe in cold water as some will react with cold water
- observe in hot water as some will react with hot water
Define relative atomic mass
The average mass of an atom compared to 1/12 of a carbon 12 atom
What the reason for adding chlorine to drinking water and a disadvantage
Adding chlorine to water kills bacteria but chlorine can be toxic
Na+ and F- have the same electron configuration. Explain why a fluoride ion is larger than a sodium ion.
Fluorine has a lower nuclear charge so the attraction to the outer shell of electron is weaker so the atomic radius is larger
Why do ionic compounds have high melting points
Because there is a giant ionic lattice with strong electrostatic forces of attraction between the oppositely charged ion so a lot of energy is required to break them
how do the results for the flame testa arrise
- electrons are promoted to a higher energy level
- they return to a lower energy shell
- the release energy at different frequency whick we can see as visible light
A student plans to titrate botanic acid solution with a solution of ethyl amine explain why this titration couldn’t be done using an indicator
This is a weak acid and weak base titration so the pH change is too gradual
Why is Electronspray ionisation is used instead of Elton impact for the ionisation of protein
The protein doesn’t break up
How are ions detected in TOF mass spectrometry and how is relative abundance of ions determined
Ions hit the detector where they gain an electron which generates a current
Current is proportional to the abundance
State one advantage of using methanol rather than hydrogen in fuel cells in use for cars
Methanol is a liquid so can be easily stored and transported
State why fuel cells don’t need to be electrically recharged
There is a continuous supply of reactants
What bonds in EDTA form coordinate bonds
4 of the O- ions and 2 N atoms
State why the concentration of aluminium sulfate solution can’t be determined by calorimetry
Colourless solution/ cant absorb visible light
Why is the enthalpy of hydration of fluoride ions more negative than the enthalpy of hydration of chlorine ions
Fluoride ions have a higher charge density because the ion is smaller
Stronger attraction to the electron
what would happen to the EMF if the surface area of the platinum electrode increases
The EMF won’t change
what is the equation for sulfur and water
SO2 +H2O → H2SOH4
reaction between phosphorus and excess oxygen
P4 +SO4 → P4O10
2 features of a reaction in a dynamic reaction
- forward and reverse reactions proceed at the same rate
- concentration of products and reactions are the same
Why is this the enthalpy of hydration for Ca2+ less exothermic that the value for Mg2+
Ca2+ has a lower charge to size ratio that Mg2+
Weak attraction to water
Explain in terms of crystal structure why silicon(IV) oxide has a higher melting point that phosphorus(V) oxide
Silicon oxide is a giant covalent structure
Strong covalent bonds need a lot of energy to overcome
Phosphorus oxide is a simple covalent structure with weak van der waals forces
Give the formula of a hydroxide of an element in period 3 used in medicine
Mg(OH)2
Why does [H2O] no show up in Kw expressions
H2O is constant
Why is water neutral at 50 degrees
Dissociation of each water molecule gives one H+ ion and OH- ions
[H+] = [OH-]
Why is the entropy for carbon dioxide greater than that for carbon
CO2 is a gas and more disordered
Suggest why two cobalt(III) complex ions have different electrode potentials
They have different ligands
Why would the emf value differ between the same half cells
It’s calculated under non standard conditions
why do isotopes have the same chemical properties
because the have the same electronic configuration
why is an indicator not added to a titration involving KMO4
KMOO4 is self indicating
what is the defentition of mean bond enthalpy
it the energy change required to break 1 mole of gaseuos bonds
how can a buffer solution be made from solutions of potassium hydroxide and ehtanoic acid
add enough KOH to the enthanoic acid so the acid is partially neutralised
KOH + CH3COOH → CH3COOK + H2O
CH3COO- can react with any added acid (H+ ions)
exaplain why solutions contain [CuCl4]2- ions are yellow
white light is absorbed only yellow light is transmitted
whats the function of a porus separator
act as a salt bridge
why are the EMF valuves if the acidic and alkaline oxygen fuel cekks are the same
they have the same overall reaction
Suggest why sodium oxide forms alkaline solutions when it reacts with water
Sodium oxide contains O2- ions which react with water to form OH- ions
Suggest why a reaction would have an enthalpy change of 0
Same number of broods broken as formed that have similar values for enthalpy
the pH of magnesium hydroxide compared to calcium hydroxide
magnesium hydroxide would be more acidic becasue magnesium hydroide is less soluable
the crystal structure of silicon dioxide and sulphur trioxide
giant covalent structure
simple molecule (macromolecule)
explain why silicon dioxide has a higher melting point than sulphur trioxide
there’s covalent bonds in silicon dioxide and there’s van der Waals forces in sulphur trioxide and covalent bonds are stronger than van der Waals forces so more energy is required to overcome them
reaction for sulphur trioxide and potassium hydroxide
SO3 + OH- → HSO4-
excess magnesium oxide and phosphoric acid
3MgO + 2H3PO4 → Mg3(PO4)2 + 3H2O
explain why colorimetry cant be used to determine the concentration of certain solution
the central metal ion has a full 3d subshell so it would be colourless
test for to distinguish between MgCl2 and AlCl3
reagent: NaOH or a group 1 hydroxide
observation with MgCl2: white ppt
observation with AlCl3: white ppt which dissolves in excess NaOH
or
reagent: group 1 carbonate
observation with MgCl2: white ppt
observation with AlCl3: white ppt and effervescence
definition of enthalpy change
the heat change at constant pressure
definition for enthalpy of hydration
the enthalpy change when one mole of gaseous ions is dissolved in water to give one mole of aqueous ions
what affects the enthalpy of hydration value
at atom with a higher charge size ratio would have a weaker attraction to the delta negative O in water
why do Zn2+ ions don’t catalyse reactions
because the don’t have a variable oxidation state
