[{"data":1,"prerenderedAt":140},["ShallowReactive",2],{"cheatsheet-predicting-and-balancing-chemical-reactions":3},{"sheet":4},{"sheetSlug":5,"topicSlugs":6,"primaryTopic":7,"title":8,"subtitle":9,"sections":10},"predicting-and-balancing-chemical-reactions",[5],5,"Predicting & Balancing Reactions","Balancing, the five reaction families, product prediction, the activity series, and when there is no reaction.",[11,23,32,65,73,81,89,97,105,123,131],{"heading":12,"kind":13,"items":14},"Balancing basics","rules",[15],{"ref":16,"mode":19,"provenance":20,"text":21,"source_hash":22},{"type":17,"topic":7,"id":18,"field":17},"rule","PBR-R001","transform","original","Atoms are conserved: same count of each element on both sides. Balance with coefficients, never by changing subscripts (that changes the substance).","b92c14a0c2f18a5d1106be122d51f9715d385070ec8ae17f82c2000a974ab649",{"heading":24,"kind":25,"items":26},"Balancing by inspection","steps",[27],{"ref":28,"mode":19,"provenance":20,"text":30,"source_hash":31},{"type":17,"topic":7,"id":29,"field":17},"PBR-R002","Start with the most complex species; balance elements in the fewest formulas first; do O and H last; clear fractions by multiplying through; reduce to smallest whole numbers.","7599b3d75755c3c2774c31c7d10f204c1c191ef425efb8d6def1ae4d0c520ee0",{"heading":33,"kind":34,"columns":35,"items":39},"The five reaction families","data",[36,37,38],"Family","Pattern","Example",[40],{"ref":41,"mode":19,"provenance":20,"rows":43,"source_hash":64},{"type":17,"topic":7,"id":42,"field":17},"PBR-R004",[44,48,52,56,60],[45,46,47],"Synthesis","A + B → AB","2Mg + O₂ → 2MgO",[49,50,51],"Decomposition","AB → A + B","2HgO → 2Hg + O₂",[53,54,55],"Single replacement","A + BC → AC + B","Zn + 2HCl → ZnCl₂ + H₂",[57,58,59],"Double replacement","AB + CD → AD + CB","AgNO₃ + NaCl → AgCl + NaNO₃",[61,62,63],"Combustion","fuel + O₂ → oxides","CH₄ + 2O₂ → CO₂ + 2H₂O","9e6d15d07352c3b1cb49d4eafa1632163bb95b4e12f3fea712a4517fe2afaf5e",{"heading":66,"kind":25,"items":67},"Combustion routine (C, H, O fuels)",[68],{"ref":69,"mode":19,"provenance":20,"text":71,"source_hash":72},{"type":17,"topic":7,"id":70,"field":17},"PBR-R011","Products CO₂ + H₂O. Balance C, then H (sets H₂O), then O (adjust O₂, often fractional), then multiply through to clear fractions and reduce.","f81eb9c328280ecdf5f8b0af3c3d7bc5379bc40f3dbabaf87e519efe38f69637",{"heading":74,"kind":34,"items":75},"Activity series",[76],{"ref":77,"mode":19,"provenance":20,"text":79,"source_hash":80},{"type":17,"topic":7,"id":78,"field":17},"PBR-R012","Metals (most → least active): Li > K > Ca > Na > Mg > Al > Mn > Zn > Fe > Ni > Sn > Pb > H > Cu > Ag > Au. A metal displaces one below it; metals above H displace H₂ from acids. Halogens: F > Cl > Br > I.","4cb11326ae500460378b53561e558bd516d28b5e25257db9374fb4c4827bfb65",{"heading":82,"kind":13,"items":83},"Single-replacement products",[84],{"ref":85,"mode":19,"provenance":20,"text":87,"source_hash":88},{"type":17,"topic":7,"id":86,"field":17},"PBR-R013","A + BX → AX + B (A above B): Zn + CuSO₄ → ZnSO₄ + Cu. Metal + acid → salt + H₂ (metal takes its low charge, Fe → Fe²⁺). Halogen + halide: Cl₂ + 2NaBr → 2NaCl + Br₂.","f3b23818cbb25aea29c15f1599100cd5361e5f50375bebf50b26a70e2d89404b",{"heading":90,"kind":13,"items":91},"Metal + nonmetal → salt",[92],{"ref":93,"mode":19,"provenance":20,"text":95,"source_hash":96},{"type":17,"topic":7,"id":94,"field":17},"PBR-R005","Cation from group (1→+1, 2→+2, 13→+3), anion from group (15→−3, 16→−2, 17→−1); balance charges. 2Na + Cl₂ → 2NaCl; 3Mg + N₂ → Mg₃N₂.","1ce98e07abed362da081694c8d9e9fedd2f4b27bbeda61b4ce6d3e253adbdf23",{"heading":98,"kind":13,"items":99},"Active metal + water",[100],{"ref":101,"mode":19,"provenance":20,"text":103,"source_hash":104},{"type":17,"topic":7,"id":102,"field":17},"PBR-R006","Group 1: 2M + 2H₂O → 2MOH + H₂ (all, cold water). Group 2 varies: Be none; Mg very slow in cold water, readily with steam (→ MgO + H₂); Ca, Sr, Ba: M + 2H₂O → M(OH)₂ + H₂. Al passivated by its oxide layer.","28881af8e4ee150d934689f01d51c14d92ccfac29c6c2e2ac1931d3e56cb24f1",{"heading":106,"kind":13,"items":107},"Oxides",[108,113,118],{"ref":109,"mode":19,"provenance":20,"text":111,"source_hash":112},{"type":17,"topic":7,"id":110,"field":17},"PBR-R008","Soluble (active-metal) oxide + H₂O → hydroxide: Na₂O + H₂O → 2NaOH; CaO + H₂O → Ca(OH)₂ (most metal oxides are insoluble and don't react). Most nonmetal oxides + H₂O → oxoacid, oxidation state preserved: SO₂ + H₂O → H₂SO₃; SO₃ + H₂O → H₂SO₄; CO₂ + H₂O → H₂CO₃.","8577af6bae86921309695f70790d015570822436d17b5d32a159a47079999801",{"ref":114,"mode":19,"provenance":20,"text":116,"source_hash":117},{"type":17,"topic":7,"id":115,"field":17},"PBR-R009","Metal oxide + acid → salt + H₂O. Nonmetal oxide + base → salt (+ H₂O): CO₂ + 2NaOH → Na₂CO₃ + H₂O.","d0f162e5b9df3807c310b63e6aeaf4cfb706afe1d4c84616d326bf302b104dcc",{"ref":119,"mode":19,"provenance":20,"text":121,"source_hash":122},{"type":17,"topic":7,"id":120,"field":17},"PBR-R007","Nonmetal + O₂ → oxide (default combustion): C → CO₂ (CO if O₂ limited), S → SO₂, P₄ → P₄O₁₀.","2face3a6feb8cf02e9d8a3d9a4953f4e6d9b7acec7848b215a882a088ce2244e",{"heading":124,"kind":13,"items":125},"Thermal decomposition",[126],{"ref":127,"mode":19,"provenance":20,"text":129,"source_hash":130},{"type":17,"topic":7,"id":128,"field":17},"PBR-R010","Δ signals: carbonate → oxide + CO₂ (CaCO₃ → CaO + CO₂); bicarbonate → carbonate + CO₂ + H₂O; heavy hydroxide → oxide + H₂O; chlorate → chloride + O₂ (2KClO₃ → 2KCl + 3O₂).","73ff69b4bf84306443c818f34c6b9de5b38b43889dbbf4c0eeb57be0223f5614",{"heading":132,"kind":133,"items":134},"When to write 'no reaction'","pitfalls",[135],{"ref":136,"mode":19,"provenance":20,"text":138,"source_hash":139},{"type":17,"topic":7,"id":137,"field":17},"PBR-R014","No reaction when a single-replacement element is below its target, a halide meets a weaker halogen, or no family pattern fits. The test is whether a pattern applies, not whether a change is visible.","018b0919eb52e2f420f83528f7bfd3029ccbc0b588151ed361da3ec21d58b648",1787246033530]