AQA GCSE 2023 questions revision well elaborated

Describe the plum pudding model of the atom - ANSWERSA ball of positive charge with randomly embedded negatively charged electrons in it. Atom contains electrons, protons and neutrons. Write the three particles in order - ANSWERSron n on Predict outer shells of tennessine - ANSWERSNumber of outer shells: 7 Reason: it is in group 7 Why tennessine was not accepted as a new element by other scientists until 2015 - ANSWERSTime needed for peer review Plan a method to obtain pure dry crystals of zinc chloride from zinc carbonate and a dilute acid - ANSWERS1. Add zinc carbonate to conical flask containing hydrochloric acid. 2. Keep adding solid until in excess. 3. Filter the mixture to remove excess zinc carbonate. 4. Heat the zinc carbonate mixture to crystallisation point using an electric heater or water bath. 5. Leave solution to crystallise. 6. Pat formed crystals dry with filter paper Two other substances that can be reacted with dilute acid to form zinc chloride - ANSWERS1. Zinc carbonate. 2. Zinc hydroxide 3. Zinc oxide 4. Zinc Explain why methane and poly (ethene) exist in different states at room temperature - ANSWERSMethane consists of much smaller molecules therefore it has weaker intermolecular forces needing less energy to overcome, therefore the boiling point is lower and remains in gaseous state. However poly(ethene) consists of larger molecules and has stronger intermolecular forces requiring higher energy to overcome. Therefore, the boiling point of poly(ethene) is much higher and it remains in solid state. What is meant by a weak acid? - ANSWERSThe acid only partially ionises, does not fully dissociate in an aqueous solution Name an indicator that can be used in titration. Give the colour change of indicator when acid from burette is added to alkali in flask - ANSWERSName of indicator: phenolpthalein Colour change: pink - colourless Or Name of indicator: damp litmus paper Colour change: blue to red Give formula of ion which makes a solution alkaline - ANSWERSOH- A solution of hydrochloric acid has a pH of 4.5 has a concentration of H+ ions of 3.16 * 10-5 mol/dm3 What is concentration of H+ ions in a solution of hydrochloric acid with pH 2.5? - ANSWERSConcentration of H+ ions = 3.16 * 10-3 How metals conduct electricity? - ANSWERSMetals have delocalised electrons which carry electrical charge throughout the structure of the metal Why do alloys not conduct electricity as well as pure metals? - ANSWERSIn alloys, different sized atoms distort the layers so movement of delocalised electrons is restricted Complete the half equation for reaction occurring at negative electrode. Al3+ + e- - Al - ANSWERSAl3+ + 3e- - Al Cryolite contains Na+ ions as well as Al3+ ions. Suggest one why reason why sodium is not a product of electrolysis - ANSWERSSodium is more reactive than aluminium. Explain how oxygen was produced from water during electrolysis of aqueous solution. - ANSWERSWater molecules break down to produce hydroxide and hydrogen ions. OH- ions are attracted to positive electrode where OH- ions are oxidised to produce oxygen molecules How student can change the apparatus to compare the volume of two gases more accurately - ANSWERSChange: use measuring cylinders instead of test tubes Reason: there is a scale on the measuring cylinder Explain why argon does not form compounds - ANSWERSArgon atoms have a stable electronic configuration so they can't transfer electrons Two observations when barium reacts with hydrochloric acid - ANSWERS1. Vigorous bubbling 2. Barium disappears Nanoparticles of titanium dioxide are used instead of fine particles of titanium dioxide for self coating windows - ANSWERS1. They have higher surface area to volume ration. 2. There is less material required for the same effect. Balanced symbol equation for barium and hydrochloric acid - ANSWERSBa + 2HCL - BaCl2 + H2 Predict whether tellerium reacts with metals - ANSWERSYes, tellerium is on the right side of the periodic table therefore it is a non metal which can react with metals so it can gain electrons