CHEMISTRY THEORY Flashcards

1
Q

Name the substance used to remove sulfur dioxide in flue gas desulfurisation.

A

calcium oxide- lime slurry

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2
Q

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.

A

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

  1. greater surface area (of zinc). frequency of collisions between (zinc and acid) particles increase
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3
Q

State the meaning of the Roman numeral (II) in the name copper(II) oxide.

A

the oxidation number of copper is +2

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4
Q

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

A

sodium propanoate
CH3CH2COO–

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5
Q

isotopes

A

different atoms of the same element with the same number of protons

different number of neutrons

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6
Q

Explain, in terms of bonding, why sodium oxide has a high melting point.

A

positive ions and negative ions

strong attraction / strong bonds

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7
Q

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

A

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

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8
Q

electrolysis

electrolyte

A

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

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9
Q

State one advantage of using hydrogen–oxygen fuel cells instead of petrol in vehicle engines.

A

no carbon dioxide evolved or more efficient

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9
Q

cryolite use

A

solvent
lowers the operating temperature
increases conductivity
carbon reacts with oxygen

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9
Q

is a reducing agent in the blast furnace

is the main impurity in iron ore

A

carbon monoxide
silicon(IV) oxide

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10
Q

(a) Name the ester formed when butanoic acid, CH3CH2CH2COOH, reacts with ethanol, CH3CH2OH.

empirical formula of it

A

ethyl butanoate

C3H6O

(water is also a product)

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11
Q

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

A

melting

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12
Q

The electrolysis of aqueous copper(II) sulfate is repeated using copper electrodes.
State what happens to the anode.

A

anode dissolves

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13
Q

State one disadvantage, other than cost, of using hydrogen–oxygen fuel cells to power cars compared to using petrol.

A

needs high pressure to store hydrogen

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14
Q

State two observations that indicate the copper(II) carbonate is in excess.

A

undissolved solid

effervescence stops on addition of more copper(II) carbonate

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15
Q

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

A

chlorine

oxygen

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16
Q

Explain how nitrogen dioxide is formed in car engines.

Name the two non‑toxic gases formed. in a catalytic converter

A

nitrogen (from air) and oxygen (from air) react react due to high temperatures of engine

carbon dioxide and nitrogen

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17
Q

Determine the value of ‘n’ in butyl propanoate.

A

7

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18
Q

(iii) State how the student decides that a suitable number of results have been obtained. titration

A

at least two results are within 0.2 cm3 or less

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19
Q

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

A

crystals form on glass rod withdrawn from solution or microscopic slide

cool the solution

solubility (of MgSO4 / solid) decreases (as temperature decreases)

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20
Q

Describe one other difference in the physical properties of Group I elements and transition
elements.

A

lower melting point, lower density, less strong

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21
Q

Suggest what is meant by the term saturated solution.

Describe how you would make a sample of limewater starting with solid calcium hydroxide

A

a solution that can dissolve no more solute at a given temperature

add excess (solid) calcium hydroxide (to water) filter

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22
Q

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

A

addition

steam, catalyst, 60 atm, 300 degree celsius

hydrogen
catalyst
high temperature

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23
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
24
Write a chemical equation for the reaction between one molecule of hydrazine, and one molecule of water.
N2H4 + H2O ⇌ N2H5+ + OH–
24
why nitrogen has a low melting point.
weak force(s) of attraction between molecules
25
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
26
has the highest rate of diffusion at room temperature in period 2
neon diatomic- n and o, f
27
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
28
structural isomer
same (molecular) formula different structural formula
28
graphite structure
layers hexagon(al) (rings of carbon)
29
aluminium no reaction amphoteric
unreactive coating of aluminium oxide neutralises both acids AND alkalis
30
Name the black solid that is produced when concentrated sulfuric acid is added to sugar, C12H22O11.
carbon
31
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
32
Identify the two functional groups present in the monomers used to produce synthetic polyamides.
carboxylic acid and amine
33
Describe why these gases diffuse.
random motion of molecules/particles
34
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) 2. 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
35
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
36
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
37
Suggest why copper, rather than other transition elements, is used for wires which conduct electricity
unreactive
38
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)
38
magnesium is added to aqueous lead(II) nitrate. ionic equation
Mg + Pb2+ => Mg2+ + Pb
39
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
40
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
41
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
42
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
43
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
44
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)
45
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
46
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
47
(i) State why these two isotopes of chlorine have the same chemical properties.
same number of electrons. same electronic configuration. 2 marks
48
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
49
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)
50
(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
51
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
52
Complete the chemical equation to show HClO3 behaving as an acid in water. HClO3 + H2O =>
ClO3- + H3O+
53
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
54
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
55
(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
56
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
57
fermentation
C6H12O6 → 2CO2 + 2C2H5OH (1) any three from- * anaerobic * 30 °C * yeast * glucose aqueous fractional distillation (of aqueous ethanol)
58
which element has a relative atomic mass that shows it has at least two isotopes.
chlorine
59
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