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AQA A-Level Chemistry - Practical’s Questions and Answers (1) Why do we use a white tile? To see indicator colour change better. (1) Why is a conical flask used? Can be swirled without losing any solution. (1) Why is swirling necessary? To ensure that solutions mix and so react completely. (1) Why does rinsing the flask with water not affect the end point? Water does not react ---> doesn't affect number of moles present. (Other 1) Outline how to carry out...

A level chemistry paper 2 Questions and Answers Silver nitrate+ nitric acid + chloride ions White precipitate Silver nitrate+ nitric acid + bromide ions Cream precipitate Silver nitrate+ nitric acid + iodide ions Yellow precipitate Substances that decolorise bromine water Alkenes Electrophiles Electron pair acceptors, attracted to electrons e.g H+ NaF and NaCl Produces misty fumes with conc sulphuric acid NaBr Produces misty and orange/brown fume...

Chemistry 9701 A-Level Questions and Answers Natures of amino acids polar, non-polar, electrically-charged Properties of amino acids white crystalline solids, high melting point, soluble in H2O Effect of pH on enzyme activity increases then decreases above the optimum pH Why does the enzyme activity decrease above optimum pH? the active site is changed due to the ionic bonds Describe the effect of substrate concentration on enzyme activity increases then const...

A-Level Chemistry Atomic structures and isotopes Questions and Answers State what is meant by the term isotopes? Atoms of the same element with different numbers of neutrons. Isotopes of specific element (carbon) have the same chemical properties. Explain why. Same number of electrons in the outer shell. What is the difference between the atomic structures of any given isotopes? You just talk about the number of neutrons present on the isotope. 2) For example, one isotope has...

Excel A level chemistry paper 1 topics Questions and Answers Atoms Made up of 3 subatomic particles - electrons, neutrons and protons Electrons - Subatomic particle - Charge of -1 - Arranged in orbitals - Relative mass of 0.0005 - negligible Nucleus - Where most of the mass of the atom is contained - Made up of protons and neutrons - Diameter is much smaller than that of whole atom Neutrons - Subatomic particle - No charge - Relative mass of 1 - Contained in nuc...

A-Level Chemistry Ion Charges Questions and Answers hyrdogren H+ sodium Na+ silver Ag+ potassium K+ lithium Li+ ammonium NH4+ barium Ba+2 calcium Ca+2 copper(II) Cu+2 magnesium Mg+2 zinc Zn+2 lead Pb+2 iron(II) Fe+2 iron(III) Fe+3 aluminium Al+3 chloride Cl- bromide Br- fluoride F- iodide I- hydroxide OH- nitrate NO3- oxide O-2 ...

AQA A-Level Chemistry - Group 2 Questions and Answers Explain the trend in atomic radius down group 2 Increases down group. Explain the trend in 1st ionisation energy down group 2 -Decreases down group. -More shielding, weaker attraction as nucleus and outer e- further apart. - Easier to remove outer e- (less energy). Explain the trend in melting points down group 2 -Generally decrease down group (not Mg). -Larger ions, distance between + metal nuclei and delocalised e- is g...

OCR A-level Chemistry Reaction Conditions and Reagents Questions and Answers Haloalkane > Nitrile NaCN or KCN (CN-) and ethanol Alkane > Haloalkane Halogen and UV light Haloalkane > Amide NH3 and ethanol Nitrile > Amine H2 and Ni catalyst Haloalkane > Alcohol NaOH Alcohol > Haloalkane Sodium halide and H2SO4 Alkene > Alcohol H2O as steam and H3PO4 Alcohol > Alkene Conc. H2SO4 or H3PO4 and heat Secondary Alco...

AQA A-Level Chemistry Amount of Substance Questions and Answers What is the relative atomic mass? the ratio of the average mass of one atom of an element to one twelfth of the mass of an atom of carbon-12 (Oxford Languages). How do you work out the relative atomic mass? Why is carbon-12 so significant? Carbon-12's atomic mass could be measured particularly accurately compared to the other elements on the periodic table. Historically, chemists and physicists used oxygen to ...

OCR A-level Chemistry - Paper 3 Questions and Answers Why does HF have a higher boiling point than CH4? -Boiling point increases as electronegativity increases -HF has hydrogen bonding, CH4 has London forces How do you prepare a standard solution? -Weigh out correct mass of solid -Dissolve in distilled water -Transfer to a 250cm^3 volumetric flask -Wash beaker with distilled water -Add washings to the volumetric flask -Make up to 250cm^3 with distilled water -Invert to ensure mi...

Transition metals OCR A Level Chemistry Questions and Answers Which 2 transition metals do not have a fully filled 4s orbital? Chromium and copper What advantage does a fully or half filled shell give a transition metal and why? Makes more stable What is the definition of a transition element? D-block element which form at least one ion with a partially filled d orbital Which 2 elements in the d block do not qualify as transition metals and why? Zinc and scandium. Their...

Common exam questions A level chemistry unit 3 Questions and Answers What is meant by an unsaturated hydrocarbon? one which contains one or more carbon-carbon double bonds What is meant by the term hydrocarbon? a molecule that contains the elements hydrogen and carbon only Recall the reagents and conditions needed to produce ethanol from bromoethane. aqueous NaOH reflux Name the organic product and mechanism when 2-bromopropane reacts with ethanolic KOH. prop-1-ene el...

Tests for Ions- A-Level Chemistry Questions and Answers What is used to test for carbonates? Hydrochloric acid How do you know if the test result is positive for carbonates? Bubbles of CO2 released- tested with limewater How do you test for sulphates? Add dilute HCl and barium chloride solution How do you know if the test result is positive for sulphates? White precipitate formed of barium sulphate How do you test for halides? Add nitric acid and then silver nit...

A-level AQA Chemistry Transition Metals Questions and Answers Transition Metal Metal that can form one or more stable ions with a partially filled d sub-level. Scandium isn't a TM because... Has an empty d-shell when Sc3+ Zinc isn't a TM because... Has a full d-shell when Zn2+ Which 2 TM have 1 electron in 4s sub-level to give stability? Chromium and Copper Which sub levels electrons fill up first and empty first? 4s What physical properties do they...

AQA A LEVEL CHEMISTRY PAPER 1 Question and Answers TOF steps 1) ionisation 2) acceleration 3) ion drift 4) detection 5) analysis Electron impact Sample vaporised and electron gun fires high energy electrons at it which knock off 1 electron from each particle, making them 1+ ions NB- can knock off more than one e or break molecular ion electrospray ionization Sample dissolved in volatile solvent then injected through needle to give fine mist which is attached to positive en...

Practical’s Chemistry AQA A-level Questions and Answers Required Practical 1 - titration and making a standard solution Making a standard solution 1. weigh the required mass of solid using a sample bottle on a 2 dp balance. 2. transfer the solid into a beaker using distilled water to wash it out- preventing any solid remaining in the sample bottle. 3. reweigh the sample bottle and work out the difference. 4. Add 100cm3 of distilled water to the beaker to dissolve the solid (small...

OCR A Level Chemistry Transition metal colours [Cu(H2O)6]2+ Pale blue Solution [Fe(H2O)6]2+ Pale green solution [Fe(H2O)6]3+ Yellow Solution [Mn(H2O)6]2+ Pale Pink Solution [Cr(H2O)6]3+ Pale Purple Solution Cu(OH)2 Pale Blue PPT Fe(OH)2 Green PPT which darkens on standing Fe(OH)3 Orange Brown PPT Mn(OH)2 Light brown PPT which darkens on standing Cr(OH)3 Grey-green PPT [Cr(OH)6]3- Dark green solution Cr2O7 2-...

AQA A-Level Chemistry - Amount of Substance Questions and Answers Relative Atomic Mass The average mass of an atom of an element, compared to that of the mass of 1/12th of the average mass of an atom of carbon-12 Relative Molecular Mass The average mass of one molecule compared to 1/12th of the mass of one atom of carbon-12 Avogadro Constant The number of particles in one mole of an atom: 6.022 x 10^23 Solvent A liquid that can have a substance dissolved into it ...

AQA A Level Chemistry- Inorganic chemistry Questions and Answers Periodic table Table that provides chemists with a structural organisation of the known chemical elements that can be used to deduce physical and chemical properties Atomic radius across Period 3 Decreases First ionisation energy across Period 3 Increases Exceptions: Drops at Al and S Melting points across Period 3 Increases from Na to Si Decreases from Si to Ar Small rise at S Explain why the me...

AQA A level - Organic Chemistry Questions and Answers Organic compounds Compounds that contain a chain of carbon atoms Number of electrons in carbons outer shell 4 so can form 4 covalent bonds Carbon-Carbon bonds are... non-polar and relatively strong Empirical formula the simplest whole number ratio of atoms of each element in a compound molecular formula a formula that tells us the actual number of atoms of each different element in a compound structura...