OCR A LEVEL CHEMISTRY Study guides, Class notes & Summaries

Isotopes Different atomic forms of the same element. Atoms with the same number of protons but a different number of neutrons Relative atomic mass The mean mass of an atom of an element, compared to 1/12th of the mass of an atom of carbon-12 Concentration= Number of moles ÷ Volume One mole 6.02×10^23 Number of moles= mass ÷ molar mass r.t.p 25 ºC 100 kPa (1 atm)

acidA species that is a proton donor. activation energyThe minimum amount of kinetic energy that particles need to have in order to react when they collide addition polymerA very long molecular chain formed by repeated addition reactions of many unsaturated alkene molecules (monomers). addition polymerisationThe process in which unsaturated alkene molecules (monomers) add on to a growing polymer chain one at a time to form a very long saturated molecular chain (the addition polymer). ...

OCR A level Chemistry Mark Scheme latest updated The chemist finds the value of Kp is greater when the experiment is repeated at a different temperature. Explain whether the temperature is higher or lower in the second experiment (2) - answers-

OCR A-level Chemistry Elaborated Enthalpy change of hydration - The enthalpy change when one mole of gaseous ions are dissolved in water to give one mole of aqueous ions Enthalpy change of solution - The enthalpy change when one mole of ionic substance dissolves in water to make a solution of infinite concentration 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 wi...

OCR A LEVEL CHEMISTRY ORGANIC SYNTHESIS WITH COMPLETE SOLUTIONS alkene undergoes what type of polymerisation - CORRECT-addition  polymerisation Alkene to alcohol - CORRECT -Electrophilic addition  conc (phosphoric) acid catalyst  steam Haloalkane to nitrile - CORRECT -nucleophilic substitution ethanolic NaCN or KCN heat Haloalkane to primary amine (also makes NH4X) - CORRECT -Nucleophilic  substitution  Excess ethanolic NH3 with no further substitution HEAT under PRESSURE ac...

Test for carbonates - correct answer - add dilute HCL - it makes carbon dioxide test for carbon dioxide by bubbling it through lime water Test for ammonium ions - correct answer -add sodium hydroxide -warm the mixture -hover damp red litmus paper over it , if it turns blue the ions are present Test for sulphate ionz (SO4 2-) - correct answer - add dilute HCL - then add BaCl2 - BaSO4 is made which is insoluble in water so a white precipitate will be formed Test for Halides (Cl-,...

OCR A LEVEL CHEMISTRY EXAM QUESTIONS AND CORRECT DETAILED ANSWERS LATEST VERSION UPDATE (2024) ALREADY GRADED A+

Define Transition element Correct Answer A d-block element that can form at least one stable ion with an incomplete d sub-shell Why aren't scandium and Zinc transition elements? Correct Answer Cannot form stable ions with an incomplete d-sub shell. Sc 3+ has an empty d-sub shell and Zn 2+ has a full d sub shell. Name the oxidation states and coloured ions for Manganese Correct Answer MnO4 - (purple) MnO4 2- (green) Mn 2+ (pale pink) Name the oxidation state and coloured ions for Tita...

What is Avagadro's constant? Correct Answer 6.02 x 10^23 number of particles in a mol Define empirical formula Correct Answer The simplest whole number ratio of atoms of each element present in a compound Define molecular formula Correct Answer The number and type of atoms of each element in a molecule What is water of crystallisation? Correct Answer Water molecules that are bonded into a crystalline structure of a compound What is the ideal gas equation? What are the units of each ...