CHEM GCSE PAPER 1 AQA

• The reactivity series is the relative ability of metals to displace other metals from their compounds
• Metal displacement reactions are when one metal reacts with another metal's compound, forming its own compound and releasing hydrogen gas.
• In an acid-base reaction, acids release H+ ions (protons) into water, while bases accept these protons to form new substances called salts and water.
• Acids can be identified by turning blue litmus paper red or white vinegar turning red cabbage purple
• In an electrolysis cell, electricity passes through molten salt or a solution containing dissolved ionic substances (electrolytes). The positive ions move towards the negative electrode (cathode) and the negative ions move towards the positive electrode (anode)
• Bases turn red litmus paper blue or white vinegar turns red cabbage pink
• Electrolysis can be used to extract pure metals from their ores by passing electric current through molten ore or aqueous solutions of salts
• Aluminium is extracted using Bayer process which involves heating bauxite with caustic soda to form aluminium oxide, then electrolysing it at high temperature to produce aluminium
• Alkalis/bases have more OH- ions than H+ ions, turning litmus paper blue or red litmus paper green.
• Stronger acids produce more H+ ions than weaker ones
• Neutralisation occurs when an acid and alkali react together, producing salt and water only.
• Weak acids only partially dissociate in solution
• The reactivity series is a way of ranking elements based on how easily they lose electrons to become positively charged ions
• Elements at the top of the reactivity series are more reactive than those lower down
• Copper is extracted using smelting where copper sulfate is heated with carbon to remove oxygen and leave behind pure copper
• The reactivity series shows how easily elements are able to displace other elements from their compounds when they are placed in water
• An alloy is a mixture of two or more elements that has different properties than any of the pure elements alone
• Alloys have specific uses such as steel being strong and hard, brass being corrosion resistant, and aluminum being lightweight
• Reactivity increases as we go up the group and across the period
• Acid + metal carbonate → Salt + water + CO2
• Neutralisation reactions occur when acids react with bases to form water and a salt
• Metal hydroxides react with acids to form salts and water
• The pH scale measures how acidic or alkaline something is on a scale of 0 - 14
• Metal + acid → Salt + hydrogen gas
• Acid + Alkali → Salt + Water
• Stronger acids are stronger reducing agents as they donate electrons easily
• Salt + dilute acid → Acid + metal hydroxide
• Reactivity increases down group 1 as there are fewer shells so it's easier for them to lose their outer electron