[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"doc-detail-207960-en":3,"doc-seo-207960-105":30,"detail-sidebar-cat-0-en-105":89},{"code":4,"msg":5,"data":6},0,"success",{"doc_id":7,"user_id":8,"nickname":9,"user_avatar":10,"doc_module":4,"category_id":11,"category_name":12,"doc_title":13,"doc_description":14,"doc_content":15,"file_id":16,"file_url":17,"file_type":18,"file_size":19,"view_count":4,"is_deleted":4,"is_public":20,"is_downloadable":20,"audit_status":20,"page_count":21,"language":22,"language_code":23,"site_id":24,"html_lang":23,"table_of_contents":25,"faqs":26,"seo_title":27,"seo_description":14,"update_tm":28,"read_time":29},207960,687207017582,"Ethan Miller","https://ap-avatar.wpscdn.com/davatar_994ba38a5ba835b3df7d355c54d3ed8d",4,"Exam","AQA GCSE Chemistry (Separate Science) Unit 4 - Chemical Changes","Learn key ideas for GCSE Chemistry Unit 4 on chemical changes, covering the reactivity series and how metals displace others in reactions. Study acid reactivity with metals, alkalis, metal oxides, and carbonates using general equations, plus naming of salts and pH behaviour in aqueous solutions. Explore redox concepts (higher tier), metal reactions with dilute acids and water, and electrolysis principles including electrodes, ions, half equations, and molten ionic compounds.","| AQA GCSE Chemistry (Separate Science) Unit 4: Chemical Changes |  |  |  |  |  |  |\n| --- | --- | --- | --- | --- | --- | --- |\n| The Reactivity Series |  |  | Reactions of Acids |  | Reactions with Bases |  |\n| Here’s a mnemonic to the order.\u003Cbr>purple (potassium) slime (sodium)\u003Cbr>can (calcium)\u003Cbr>make (magnesium) a (aluminium)\u003Cbr>careless (carbon) zebra (zinc)\u003Cbr>insane (iron)\u003Cbr>try (tin)\u003Cbr>learning (lead)\u003Cbr>how (hydrogen) camels (copper) surprise (silver) gorillas (gold)\u003Cbr>The reactivity series is | help you learn\u003Cbr>carbon\u003Cbr>hydrogen | | The general formula for the reaction between an acid and a metal is:\u003Cbr>acid + metal  salt + hydrogen\u003Cbr>For example: hydrochloric acid + sodium  sodium chloride + hydrogen\u003Cbr>2HCl + 2Na  2NaCl + H₂\u003Cbr>When an acid reacts with an alkali, a neutralisation reaction takes place and a salt and water are produced.\u003Cbr>The general formula for this kind of reaction is acid + alkali  salt + water hydrochloric acid + sodium hydroxide  sodium chloride + water\u003Cbr>HCl + NaOH  NaCl + H₂O |  | The general formula for the reaction between an acid and a metal oxide is:\u003Cbr>acid + metal oxide  salt + water\u003Cbr>sulfuric acid + copper oxide  copper sulfate + water H₂SO₄ + CuO  CuSO₄ + H₂O\u003Cbr>Reactions with Carbonates\u003Cbr>The general formula for the reaction between an acid and a carbonate is:\u003Cbr>acid + carbonate  salt + water + carbon dioxide\u003Cbr>hydrochloric acid + calcium carbonate  calcium chloride + water + carbon dioxide\u003Cbr>pH Scale\u003Cbr>\u003Cbr>In aqueous solutions, acids produce H+ ions and alkalis produce OH-ions.\u003Cbr>Neutral solutions are pH7 and are neither acids nor alkalis.\u003Cbr>For example, in neutralisation reactions, hydrogen ions from an acid react with hydroxide ions from an alkali to produce water:\u003Cbr>H+ + OH-  H₂O |  |\n|  |  |  | Naming Salts\u003Cbr>The first part comes from the metal in the metal carbonate, oxide or hydroxide. The second part of the name comes from the acid that was used to make it.\u003Cbr>For example, sodium chloride. | Acid Used Salt Produced hydrochloric chloride nitric nitrate sulfuric sulfate |  |  |\n|  | a league table for metals. The more reactive metals are |  |  |  |  |  |\n| near the top of the table with the least reactive near the bottom. In chemical reactions, a more reactive metal will displace a less reactive metal.\u003Cbr>Reactions of Metals with Water\u003Cbr>Metals, when reacted with water, produce a metal hydroxide and hydrogen. lithium + water  lithium hydroxide + hydrogen\u003Cbr>2Li + 2H₂O  2LiOH + H₂\u003Cbr>The more reactive a metal is the faster the reaction. |  |  |  |  |  |  |\n|  |  |  | Redox Reactions (Higher Tier Only)\u003Cbr>When metals react with acids, they undergo a redox reaction. A redox reaction occurs when both oxidation and reduction take place at the same time.\u003Cbr>For example:\u003Cbr>2H+ + Ca  Ca²+ + H₂\u003Cbr>The ionic equation can be further split into two half equations. Ca  Ca²+ + 2e\u003Cbr>Oxidation is loss of electrons.\u003Cbr>2H+ + 2e-  H₂\u003Cbr>Reduction is gaining of electrons. |  |  |  |\n| Reactions of Metals with Dilute Acid |  |  |  |  |  |  |\n| Metals, when reacted with acids, produce a salt and hydrogen.\u003Cbr>Sodium + hydrochloric acid  sodium chloride + hydrogen\u003Cbr>2Na + 2HCl  2NaCl + H₂\u003Cbr>Metals that are below hydrogen in the reactivity series do not react with dilute acids. |  |  |  |  |  |  |\n|  |  |  |  |  |  |  |\n\nPage 1 of 3 visit [twinkl.com](twinkl.com)  \n\n| AQA GCSE Chemistry (Separate Science) Unit 4: Chemical Changes |  |  |  |  |  |\n| --- | --- | --- | --- | --- | --- |\n| Making Soluble Salts |  | Strong and Weak Acids (Higher Tier Only) | During the process of electrolysis, opposites attract. The positively-charged ions will be attracted toward the negative electrode. The negatively-charged ions will be attracted towards the positive electrode.\u003Cbr>When ions reach the electrodes, the charges are lost and they become elements.\u003Cbr>The positive electrode is called the anode.\u003Cbr>The negative electrode is called the cathode. | Electrolysis of Molten Ionic Compounds – L","cbCaiteeDCpW1ksa","https://ap.wps.com/l/cbCaiteeDCpW1ksa","pdf",345338,1,3,"English","en",105,"# The Reactivity Series\n## Reactions of Acids\n## Reactions with Bases\n# Reactions of Metals\n## Metals with Water\n## Metals with Dilute Acid\n# Redox Reactions (Higher Tier)\n# pH Scale\n# Naming Salts\n# Making Soluble Salts\n# Strong and Weak Acids (Higher Tier)\n# Electrolysis\n## Electrolysis of Molten Ionic Compounds – Lead Bromide","[{\"question\":\"What does the reactivity series tell you about metal displacement reactions?\",\"answer\":\"More reactive metals are higher in the reactivity series and can displace less reactive metals in reactions.\"},{\"question\":\"What are the general products when an acid reacts with a metal, an alkali, a metal oxide, or a carbonate?\",\"answer\":\"Acid + metal gives a salt and hydrogen; acid + alkali gives a salt and water (neutralisation); acid + metal oxide gives a salt and water; acid + carbonate gives a salt, water, and carbon dioxide.\"},{\"question\":\"How does electrolysis of molten lead bromide work at the electrodes?\",\"answer\":\"In molten ionic compounds, ions move and carry charge. Lead ions are attracted to the cathode and gain electrons (reduction), while bromide ions are attracted to the anode and lose electrons (oxidation).\"}]","AQA GCSE Chemistry (Separate Science) Unit 4 - Chemical Changes | PDF",1788601920,8,{"code":4,"msg":31,"data":32},"ok",{"site_id":24,"language":23,"slug":33,"title":13,"keywords":34,"description":14,"schema_data":35,"social_meta":84,"head_meta":86,"extra_data":88,"updated_unix":28},"aqa-gcse-chemistry-separate-science-unit-4-chemical-changes","",{"@graph":36,"@context":83},[37,52,66],{"@type":38,"itemListElement":39},"BreadcrumbList",[40,44,48,50],{"item":41,"name":42,"@type":43,"position":20},"https://docshare.wps.com","Home","ListItem",{"item":45,"name":46,"@type":43,"position":47},"https://docshare.wps.com/document/","Document",2,{"item":49,"name":12,"@type":43,"position":21},"https://docshare.wps.com/document/exam/",{"item":51,"name":13,"@type":43,"position":11},"https://docshare.wps.com/document/aqa-gcse-chemistry-separate-science-unit-4-chemical-changes/207960/",{"url":51,"name":13,"@type":53,"author":54,"headline":13,"publisher":56,"fileFormat":59,"inLanguage":23,"description":14,"dateModified":60,"datePublished":60,"encodingFormat":59,"isAccessibleForFree":61,"interactionStatistic":62},"DigitalDocument",{"name":9,"@type":55},"Person",{"url":41,"name":57,"@type":58},"DocShare","Organization","application/pdf","2026-09-05",true,{"@type":63,"interactionType":64,"userInteractionCount":4},"InteractionCounter",{"@type":65},"ViewAction",{"@type":67,"mainEntity":68},"FAQPage",[69,75,79],{"name":70,"@type":71,"acceptedAnswer":72},"What does the reactivity series tell you about metal displacement reactions?","Question",{"text":73,"@type":74},"More reactive metals are higher in the reactivity series and can displace less reactive metals in reactions.","Answer",{"name":76,"@type":71,"acceptedAnswer":77},"What are the general products when an acid reacts with a metal, an alkali, a metal oxide, or a carbonate?",{"text":78,"@type":74},"Acid + metal gives a salt and hydrogen; acid + alkali gives a salt and water (neutralisation); acid + metal oxide gives a salt and water; acid + carbonate gives a salt, water, and carbon dioxide.",{"name":80,"@type":71,"acceptedAnswer":81},"How does electrolysis of molten lead bromide work at the electrodes?",{"text":82,"@type":74},"In molten ionic compounds, ions move and carry charge. Lead ions are attracted to the cathode and gain electrons (reduction), while bromide ions are attracted to the anode and lose electrons (oxidation).","https://schema.org",{"og:url":51,"og:type":85,"og:title":13,"og:site_name":57,"og:description":14},"article",{"robots":87,"canonical":51},"index,follow",{"doc_id":7,"site_id":24},{"code":4,"msg":5,"data":90},[91,95,99,102,107,112,117,121,126,129,133],{"id":20,"doc_module":4,"doc_module_name":46,"category_name":92,"show_sort_weight":93,"slug":94},"Story & Novel",90,"story-novel",{"id":47,"doc_module":4,"doc_module_name":46,"category_name":96,"show_sort_weight":97,"slug":98},"Literature",80,"literature",{"id":11,"doc_module":4,"doc_module_name":46,"category_name":12,"show_sort_weight":100,"slug":101},70,"exam",{"id":103,"doc_module":4,"doc_module_name":46,"category_name":104,"show_sort_weight":105,"slug":106},5,"Comic",60,"comic",{"id":108,"doc_module":4,"doc_module_name":46,"category_name":109,"show_sort_weight":110,"slug":111},6,"Technology",50,"technology",{"id":113,"doc_module":4,"doc_module_name":46,"category_name":114,"show_sort_weight":115,"slug":116},7,"Healthcare",40,"healthcare",{"id":29,"doc_module":4,"doc_module_name":46,"category_name":118,"show_sort_weight":119,"slug":120},"Research & Report",30,"research-report",{"id":122,"doc_module":4,"doc_module_name":46,"category_name":123,"show_sort_weight":124,"slug":125},9,"Religion & Spirituality",20,"religion-spirituality",{"id":124,"doc_module":4,"doc_module_name":46,"category_name":127,"show_sort_weight":124,"slug":128},"World Cup","world-cup",{"id":130,"doc_module":4,"doc_module_name":46,"category_name":131,"show_sort_weight":130,"slug":132},10,"Lifestyle","lifestyle",{"id":134,"doc_module":4,"doc_module_name":46,"category_name":135,"show_sort_weight":103,"slug":136},19,"General","general"]