GCSE›Edexcel GCSE Chemistry›Mind mapsAcidsEdexcel GCSE Chemistry: Mind mapStudy pack PDFAlso for this subtopic:Revision notesFlashcardsSubtopic testCover factsAcids and pHAcids release HX+\ce{H+}HX+ ions in solutionAlkalis release OHX−\ce{OH-}OHX− ionspH 7 neutral, below 7 acidicLitmus: red in acid, blue in alkaliPhenolphthalein: colourless in acid, pink in alkaliStrength (Higher)Strong acid fully dissociates into ionsWeak acid only partially dissociatesDilute or concentrated = amount dissolvedTen times more H+ gives pH down 1ReactionsAcid + metal → salt + hydrogenAcid + oxide or hydroxide → salt + waterAcid + carbonate → salt + water + CO2Neutralisation: HX++OHX−→HX2O\ce{H+ + OH- -> H2O}HX++OHX−HX2OAcidsacids, bases and saltsH+OH-pHGas testsHydrogen: lit splint gives squeaky popCarbon dioxide turns limewater cloudyMaking saltsInsoluble base: add excess, then filterSoluble alkali: use titrationInsoluble salt: mix solutions, filter the precipitateNa, K, NH4 salts and nitrates always solubleChlorides soluble except silver and leadExam tipsConcentrated does not mean strongCopper sulfate practical: excess copper oxide, filter