Kimia

• Molekul atom relatif suatu unsur diperlukan untuk menentukan massa molekul relatif suatu senyawa
• Massa molekul relatif (Mr) dinyatakan dengan menjumlahkan massa atom relatif atom-atom unsur pembentuk senyawa
• Persamaan umum gas:

  • P V = nRT
  • Contoh soal:
  • Hitung volum 5 mol gas pada tekanan 152 mm Hg dan temperatur 27 0 C!
  • V = 615 L
• Atom Karlson has 4 valence electrons, allowing it to form 4 covalent bonds
• Atom Karlson can form single, double, or triple bonds with other Karlson atoms
• Bonds between carbon atoms can form linear, branched, or cyclic chains
• Hydrocarbons can be Aliphatic or Cyclic
• Hydrocarbons are relatively small in size, making them easily surrounded by other atoms
• Isomers can be formed
• Primary Carbon Atom: Carbon atom that bonds with only one other carbon atom
• Secondary Carbon Atom: Carbon atom that bonds with two other carbon atoms
• Tertiary Carbon Atom: Carbon atom that bonds with three other carbon atoms
• Quaternary Carbon Atom: Carbon atom that bonds with four other carbon atoms
• Alkanes: Saturated hydrocarbons
• Naming Alkanes: Follow the longest chain rule, assign the lowest number to the alkyl group
• Branching: Determine the main chain, write the longest chain first, then the branch number, alkyl group name
• If there are multiple alkyl groups of the same type, use di, tri, tetra, etc.
• When there are two equal-length chains, choose the main chain with the most branches
• Physical properties of Alkanes: Melting and boiling points increase with the number of carbon atoms
• Alkanes with branched chains have lower boiling points than straight-chain alkanes with the same molecular weight
• Alkanes with branched chains have a boiling point 1°C lower than alkanes with straight chains
• Unsaturated hydrocarbons have double or triple bonds
• Perfect combustion reaction with excess oxygen: Hydrocarbon + Oxygen → Carbon Dioxide + Water
• Incomplete combustion reaction with insufficient oxygen: Hydrocarbon + Oxygen → Carbon Monoxide + Water
• Cracking of alkanes results in smaller alkane molecules, alkene molecules, and hydrogen molecules
• Alkenes with more than one double bond end in -diene for two double bonds and -triene for three double bonds
• Substitution reaction by halogen: Hydrocarbon + Cl2 (UV light) → Chloroalkane + HCl
• Uses of alkanes:

  • Fuel for household, vehicles, and industries
  • Raw material for petrochemical industries
• Naming of alkenes with branched chains follows the same rules as naming alkanes
• Addition reaction: Main chain with double bond reacts with hydrogen to form alkane
• Addition reaction: Main chain with double bond reacts with halogen to form haloalkane
• Addition reaction: Main chain with double bond reacts with hydrogen halide to form haloalkane
• Symmetric alkenes produce one haloalkane
• Unsymmetric alkenes produce two haloalkanes, following Markovnikov's rule
• Polymerization reaction: Formation of compounds with repeated -C-C- units
• Reaksi Polimerisasi:

  • Pembentukan senyawa yang lebih besar dari beberapa molekul yang lebih kecil
  • Contoh: Reaksi polimerisasi etena membentuk polietena
• Reaksi Oksidasi Oleh KMnO4:

  • Menghasilkan alkohol bervalensi 3
  • Contoh: Reaksi oksidasi etena menghasilkan etanadiol
• Sifat-sifat Alkuna:

  • Bersifat nonpolar sehingga dapat larut dalam pelarut nonpolar
  • Titik leleh dan titik didih alkuna bertambah seiring dengan pertambahan jumlah atom karbon
  • Kerapatan semakin besar seiring dengan penambahan jumlah atom karbon
• Kegunaan Alkuna:

  • Digunakan pada pengelasan dan pemotongan logam
• Isomerisasi:

  • Ada isomerisasi struktur dan isomerisasi optik
  • Isomerisasi struktur terjadi karena perbedaan kerangka karbon
  • Isomerisasi optik terjadi karena perbedaan cara memutar bidang cahaya