Zadanie 1a
Outline why the first ionization energies of all the elements in the table are positive, whereas the first electron affinities of most of them are negative.
Chemistry HL Paper 3, May 2023, TZ1
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Dodaj cały arkusz do zestawuZadanie 1b
Explain the decrease in first ionization energy from magnesium to aluminium.
Zadanie 1c
The first electron affinity of magnesium is positive. Sketch the 3s and 3p orbital filling diagram of the species formed when one electron is added to a gaseous magnesium atom.
- Materiał graficzny
Zadanie 1d
Suggest one reason why the first electron affinity of magnesium is positive.
Zadanie 1e
Suggest reasons why argon has the largest first ionization energy and the largest positive first electron affinity of the elements in period 3. Largest first ionization energy: Largest positive first electron affinity:
Zadanie 1f
Suggest whether the first electron affinity of xenon is greater or smaller than that of argon, and give one reason for your answer.
Zadanie 2a
(i) Identify the oxidation state of metal S in SSO4. (ii) Deduce the order of reactivity of the five metals, from the most reactive to the least reactive.
Zadanie 2b
Sketch the voltaic cell that would produce the greatest cell potential (EMF) using the metals and solutions in this experiment. On your diagram label the metal and the solution in each half-cell, the anode, the cathode, the salt bridge and the direction of…
Zadanie 2c
A steel bolt is to be coated with a thin layer of a metal by electroplating, using an aqueous solution of a salt of the coating metal as the electrolyte. Deduce one metal that could be deposited on the bolt with high efficiency. Use section 19 of the data…
Zadanie 3a
Iron is extracted in a blast furnace by reducing iron(III) oxide with carbon monoxide. Fe2O3(s) + 3 CO(g) → 2 Fe(s) + 3 CO2(g) Calculate the percentage atom economy for the production of iron by this reaction. Use section 1 of the data booklet.
Zadanie 3c
Poly(chloroethene) is made from the monomer CH2=CHCl by addition polymerization. Nylon-6,6 is made from the monomers H2N(CH2)6NH2 and HOOC(CH2)4COOH by condensation polymerization. Distinguish between these two types of polymerization by…
Zadanie 4a
Brass is an alloy of copper and zinc. Explain why brass is harder and stronger, but a poorer conductor of electricity, than pure copper.
Zadanie 4b
The concentration of copper(II) ions in a sample of pond water is determined with a colorimeter. The absorbance of standard solutions of known concentration is measured and a calibration curve is plotted. Sketch the typical shape of the calibration curve on…
- Materiał graficzny
Zadanie 7a
Glucose, C6H12O6, is oxidized in the body by respiration to carbon dioxide and water. The standard enthalpy of combustion of glucose is −2803 kJ mol−1. Determine the energy, in kJ, released by the complete oxidation of 12.5 g of glucose.
Zadanie 7b
Sucrose, C12H22O11, and the triglyceride glyceryl tripalmitate, C51H98O6, can both be completely oxidized in the body to carbon dioxide and water. Write balanced equations for the complete oxidation of each compound. C12H22O11:…
Zadanie 8a
Determine the identity of the amino acid in spot B by calculating its RF value from the chromatogram.
- Materiał graficzny
Zadanie 8b
Spot X is known to be either glutamine or isoleucine. The structures of the two amino acids are shown. Predict, with reference to the structures, which amino acid is more likely to be in spot X. Use the RF values in the table.
- Materiał graficzny
Zadanie 10a
4-Nitrophenol is used as an acid-base indicator. It exists as two forms, X and Y, which differ in colour. Explain which form, X or Y, predominates at pH 11.
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Zadanie 13a
A direct ethanol fuel cell has an acidic electrolyte. At the anode, ethanol is oxidized to carbon dioxide gas. At the cathode, oxygen is reduced to water. Write equations for the half-reaction at the anode and the half-reaction at the cathode, and the overall…
Zadanie 14b
Outline what happens to a molecule of methane, a greenhouse gas, when it absorbs infrared radiation.
Zadanie 14c
The global warming potential (GWP) of a gas compares the heat it absorbs with the heat absorbed by an equal mass of carbon dioxide. The GWP of the refrigerant C2H2F4 is approximately 1300. Estimate the heat absorbed by one mole of C2H2F4 relative…
Zadanie 17a
Calcium carbonate and magnesium hydroxide are two antacids. Write an equation for the reaction of each antacid with excess hydrochloric acid in the stomach. Calcium carbonate: Magnesium hydroxide:
Zadanie 17b
One antacid tablet contains 1.50 g of calcium carbonate and a second tablet contains 1.50 g of magnesium hydroxide. Show by calculation that the tablet of magnesium hydroxide would neutralize more hydrochloric acid than the tablet of calcium carbonate.
Zadanie 19a
Ephedrine is a decongestant found in some cold remedies. Its structure is shown. Deduce which two carbon atoms in a molecule of ephedrine are chiral. For each of them, state the four different atoms or groups bonded to it.
- Materiał graficzny
Zadanie 21a
A laboratory tests a urine sample for steroid drugs. Before the compounds in the extract are identified, they must be separated from one another. State a technique that can be used to separate the compounds.
Zadanie 21b
A forensic laboratory identifies a solvent by mass spectrometry. The mass spectrum of a sample of pentan-3-one, CH3CH2COCH2CH3, Mr 86, is shown. Explain how the peaks at m/z 86 and m/z 57 support the identification of the compound as…
- Materiał graficzny
Zadanie 21c
A detector tube for propan-2-ol vapour in workplace air contains orange dichromate ions, which turn green as they are reduced to chromium(III) ions. Cr2O72−(aq) + 14 H+(aq) + 6 e− → 2 Cr3+(aq) + 7 H2O(l) Deduce the half-equation for the oxidation of…