CHEMISTRY THEORY Flashcards
Name the substance used to remove sulfur dioxide in flue gas desulfurisation.
calcium oxide- lime slurry
why increasing the temperature increases the rate of the reaction.
Explain, in terms of collision theory, why the rate of reaction increases if powdered zinc is used.
M1 kinetic energy of particles increases
M2 frequency of collisions between particles increases
M3 higher percentage / proportion / fraction of collisions / particles have energy greater than / equal to activation energy
- greater surface area (of zinc). frequency of collisions between (zinc and acid) particles increase
State the meaning of the Roman numeral (II) in the name copper(II) oxide.
the oxidation number of copper is +2
Propanoic acid reacts with aqueous sodium carbonate to form a salt.
(i) Suggest the name of the salt formed.
……………………………………………………………………………………………………………………… [1]
(ii) Suggest the formula of the anion in this salt
sodium propanoate
CH3CH2COO–
isotopes
different atoms of the same element with the same number of protons
different number of neutrons
Explain, in terms of bonding, why sodium oxide has a high melting point.
positive ions and negative ions
strong attraction / strong bonds
The rate of reaction is highest at the start of the reaction. The rate decreases and eventually
becomes zero.
Explain why the rate of reaction is highest at the start of the reaction
then why rate becomes zero
concentration of hydrogen peroxide is highest at the start / particles of hydrogen peroxide are closest together at the start 1 OR
collision frequency is highest at the start
all of it has reacted
electrolysis
electrolyte
breakdown by the passage of electricity of an ionic compound in molten or aqueous (state)
ionic compound in molten or aqueous state that conducts electricity
State one advantage of using hydrogen–oxygen fuel cells instead of petrol in vehicle engines.
no carbon dioxide evolved or more efficient
cryolite use
solvent
lowers the operating temperature
increases conductivity
carbon reacts with oxygen
is a reducing agent in the blast furnace
is the main impurity in iron ore
carbon monoxide
silicon(IV) oxide
(a) Name the ester formed when butanoic acid, CH3CH2CH2COOH, reacts with ethanol, CH3CH2OH.
empirical formula of it
ethyl butanoate
C3H6O
(water is also a product)
When solid magnesium fluoride is dissolved in water it forms a solution that conducts electricity. State one other change that can be made to solid magnesium fluoride to allow it to conduct electricity
melting
The electrolysis of aqueous copper(II) sulfate is repeated using copper electrodes.
State what happens to the anode.
anode dissolves
State one disadvantage, other than cost, of using hydrogen–oxygen fuel cells to power cars compared to using petrol.
needs high pressure to store hydrogen
State two observations that indicate the copper(II) carbonate is in excess.
undissolved solid
effervescence stops on addition of more copper(II) carbonate
has aqueous ions which form a white precipitate when added to aqueous silver ions
is added to molten iron to remove impurities in the steel making process
chlorine
oxygen
Explain how nitrogen dioxide is formed in car engines.
Name the two non‑toxic gases formed. in a catalytic converter
nitrogen (from air) and oxygen (from air) react react due to high temperatures of engine
carbon dioxide and nitrogen
Determine the value of ‘n’ in butyl propanoate.
7
(iii) State how the student decides that a suitable number of results have been obtained. titration
at least two results are within 0.2 cm3 or less
Suggest what is observed when the solution is saturated
Describe how crystals are produced from a hot saturated solution.
Suggest why more crystals of magnesium sulfate appear on cooling
crystals form on glass rod withdrawn from solution or microscopic slide
cool the solution
solubility (of MgSO4 / solid) decreases (as temperature decreases)
Describe one other difference in the physical properties of Group I elements and transition
elements.
lower melting point, lower density, less strong
Suggest what is meant by the term saturated solution.
Describe how you would make a sample of limewater starting with solid calcium hydroxide
a solution that can dissolve no more solute at a given temperature
add excess (solid) calcium hydroxide (to water) filter
State the type of reaction that occurs during reaction 3. ethene to ethanol
(iii) State the reagents and conditions needed for reaction 3
alkene to alkane conversion conditions
addition
steam, catalyst, 60 atm, 300 degree celsius
hydrogen
catalyst
high temperature
Explain, in terms of attractive forces between particles, why LiCl is a solid at room temperature but NCl 3 is a liquid with a relatively low boiling point.
ionic bonds in LiCl
attraction between molecules in NCl3
weaker attraction (between particles) in NCl3
Write a chemical equation for the reaction between one molecule of hydrazine, and
one molecule of water.
N2H4 + H2O ⇌ N2H5+ + OH–
why nitrogen has a low melting
point.
weak force(s) of attraction between molecules
State two general characteristics, other than the same general formula, of all homologous series.
same general formula
same/ similar chemical properties or reactions
(contain) the same functional group
(consecutive members) differ by CH2
physical properties vary in predictable manner / show trends / gradually change
has the highest rate of diffusion at room temperature in period 2
neon
diatomic- n and o, f
State the effect, if any, on the position of the equilibrium when the following changes are made. haber
temperature is reduced
pressure is reduced
(position of) equilibrium moves to right-hand side
reaction is exothermic
(position of) equilibrium moves to left-hand side
more (gaseous) moles on left hand side
structural isomer
same (molecular) formula different structural formula
graphite structure
layers
hexagon(al) (rings of carbon)
aluminium no reaction
amphoteric
unreactive coating of aluminium oxide
neutralises both acids AND alkalis
Name the black solid that is produced when concentrated sulfuric acid is added to sugar,
C12H22O11.
carbon
endothermic and exothermic
endothermic- energy released when bonds form is less than energy absorbed to break bonds
exo- energy released when bonds form is greater than energy absorbed to break bonds
-bond making releases energy and bond breaking requires energy
exo- products are at lower energy than reactants
Identify the two functional groups present in the monomers used to produce synthetic polyamides.
carboxylic acid and amine
Describe why these gases diffuse.
random motion of molecules/particles
lead iodide using lead nitrate and sodium iodide. precipitation process
zinc carbonate plus sulfuric acid salt prep
(add) water (to both salts) (1)
dissolve both salts / make solutions (1)
filter (lead(II) iodide)(1)
wash (residue of lead(II) iodide) with water AND dry e.g. with filter paper / description of washing and drying (1)
Pb(NO3)2 + 2 NaI → 2NaNO3 + PbI2 ORPb2+ +2I– →PbI2(1)
- add zinc carbonate to sulfuric acid until
* it stops dissolving OR
* no more effervescence (1)
filter (zinc carbonate) (1)
evaporation of filtrate to form dry crystals (1) ZnCO3 + H2SO4 → ZnSO4 + CO2 + H2O CO2
iron extraction-
enters blast furnace
leaves blast furnace
uses of coke in blast furnace
air
calcium silicate
.(coke)
releases heat (when it reacts with oxygen or reacts in air) OR (acts as a) fuel OR increases temperature (in the furnace) / heats (the furnace) OR source of energy
- (coke or carbon monoxide) reduces iron oxide
OR is a reducing agent
OR converts iron oxide to iron / removes oxygen from iron oxide - (coke)
reacts with oxygen to form carbon monoxide OR reacts with carbon dioxide to form carbon monoxide
iron extraction- everything that enters BF
everything that leaves BF
Name two substances that react together, in the blast furnace, to produce this high temperature.
(v) Name two waste gases that leave the blast furnace
coke, iron ore- hematite, limestone , air
slag calcium silicate, molten iron
reaction between coke and oxygen
carbon dioxide and nitrogen
Suggest why copper, rather than other transition elements, is used for wires which conduct electricity
unreactive
20.0cm3 of dilute sulfuric acid neutralises 25.0cm3 of 1.00mol/dm3
aqueous sodium hydroxide.
At the end of the titration the conical flask contains aqueous sodium sulfate with the dissolved indicator as an impurity.
(b) Describe how to prepare a pure sample of sodium sulfate crystals from the original solutions
of dilute sulfuric acid and aqueous sodium hydroxide of the same concentrations.
M1 repeat without indicator using same volumes OR remove indicator by adding charcoal or carbon and filtering (1)
M2 evaporate / heat/warm/ boilleave in hot place (1)
M3 until most of the water is gone / some water left / saturation(point) / crystallisation (point) / evaporate some of the water (1)
M4 cool/ eave to crystallise(1)
M5 description of drying (1)
magnesium is added to aqueous lead(II) nitrate. ionic equation
Mg + Pb2+ => Mg2+ + Pb
Give two advantages of manufacturing ethanol by fermentation compared to manufacturing ethanol from ethene.
carbohydrates are renewable
fossil fuels are non-renewable
lower temperature- lower energy
lower pressure
hydration is equilibrium meaning lower yield
purer product
faster reaction
continuous process
ionic bond
What does the term condensation mean when used to describe this type of polymer?
oppositely charged ions
ions are attracted
water is a product when polymer is made
Part of the definition of relative atomic mass is ‘the average mass of naturally occurring atoms of an element’.
Some relative atomic masses are not whole numbers.
Element Y has only two different types of atom, 69Y and 71Y.
The ratio of atoms present in element Y is shown.
69Y: 71Y = 3:2
● Calculate the relative atomic mass of element Y to one decimal place.
69.8
What is meant by the term unsaturated?
What is the name given to the reactive part of any organic molecule?
not all (C-C) bonds are single
functional group
Ethanol is manufactured by two different processes.
For each process, name the organic reactant and state the type of reaction.
organic reactant .
type of reaction
sugar- fermentation
ethene-hydration
What can be done to solid magnesium fluoride to make it conduct electricity?
heat until molten or dissolve in water (1)
moving ions / mobile ions (1)
why magnesium fluoride has a
high melting point.
Explain, using your knowledge of structure and bonding, why carbonyl fluoride has a low melting point.
forces of attraction between oppositely charged ions / ionic bonds (1)
strong / need a lot of energy to break / weaken
forces of attraction between molecules (1) weak / need a small of energy to break / weake
what happens to rate of reaction as time increases
rate decreases, concentration of acid decreases, particles further apart / less particles per unit volume (1) fewer collisions per unit time / lower collision frequency
reaction stops because all hydrogen peroxide is used up/reacted
(i) State why these two isotopes of chlorine have the same chemical properties.
same number of electrons.
same electronic configuration. 2 marks
Explain how sacrificial protection prevents rusting.
metal more reactive than iron/higher in reactivity series
corrodes/oxidises/reacts in preference to iron
acts as a barrier which prevents contact between iron and water or air/oxygen
Explain, in terms of particles, why brass is harder than pure zinc.
exists as layers (1)
(alloy) contains different sized (copper) atoms (1)
makes it more difficult for layers (of atoms) to slide over each slip/shift other (1)
(iii) Describe what should be done during step 3 to ensure there is a maximum yield of crystals. sodium carbonate and HCl
rinse the residue with distilled water to ensure all sodium chloride is collected
fractional distillation of air process
M1 air is made into a liquid
M2 (allow air to) boil or evaporate
M3 condense the vapours / collect the vapours in order (of evaporation
Complete the chemical equation to show HClO3 behaving as an acid in water.
HClO3 + H2O =>
ClO3- + H3O+
Steps 1–5 were done correctly but the mass of crystals obtained was less than the maximum mass. copper sulfate
some copper(II) sulfate remains in solution / some copper(II) sulfate does not form crystals
OR
some of the crystals decomposed
OR
some crystals lost in transfer
State and explain the effect, if any, of removing water from the mixture on the amount of ester at equilibrium.
more ester- equilibrium shifts to right to replace water lost
(b) Describe how to do a flame test on a sample of a salt.
(compound / salt) on wooden splint or (nichrome / platinum) wire (1) into (roaring) Bunsen flame
Aqueous silver nitrate produces a yellow precipitate with both iodide ions and carbonate ions.
When testing an unknown solution for iodide ions, the aqueous silver nitrate is acidified. Explain why the aqueous silver nitrate is acidified
(nitric) acid reacts with / removes carbonate ions
fermentation
C6H12O6 → 2CO2 + 2C2H5OH (1)
any three from-
* anaerobic
* 30 °C
* yeast
* glucose aqueous
fractional distillation (of aqueous ethanol)
which element has a relative atomic mass that shows it has at least two isotopes.
chlorine
Suggest why the green precipitate turns red-brown at the surface.
- it (iron(II) hydroxide) is oxidised
- to form iron(III) (hydroxide) / (oxide)
- by (iron(II) hydroxide reacting with) air / oxygen
