B. Chemical Reaction Equation B. Persamaan Reaksi Kimia

Teaching Learning Objectivers The student can explain signification chemical reaction equation. The student can getting over with balance simple the chemical reaction equation. The student can getting over wih the balance the chemical reaction equation with matematical equation method.

A substance is called having chemical changes when it transforms into novel substance with defferent properties form its nature. This change is also called as chemical reaction. The chemical reaction happened is indicated with flocculation, gas forming, color change, or heat transfer.

The chemical reaction equation menggambarkan reaksi yang terdiri atas rumus kimia zat yang bereaksi dan zat hasil reaksi disertai koefisien masing-masing zat yang dibatasi tanda panah Zat yang bereaksi (reaktan) ditulis disebelah kiri anak panah sedangkan zat hasil (produk) ditulis disebelah kanan anak panah. Koefisien reaksi adalah angka yang ditempatkan di depan rumus molekul senyawa .

Persamaan reaksi kimia yang lengkap terdapat koefisien reaksi dan wujud zat. Example Mg(s) + O2(g) MgO(s) 1 atom Mg 2 atom O 1 atom Mg + 1 atom O Mg + O2 2 MgO 1 atom Mg 2 atom O 2 atom Mg + 2 atom O 2 Mg + O2 2MgO 2 atom Mg 2 atom O 2 atom Mg + 2 atom O

Na(s) + O2(g) Na2O(s) Na + O2 2Na2O 4Na + O2 2Na2O 1 atom Na 2 atom O

Balancing the chemical equation with mathematical equation method Example KMnO4(aq) + HCl(aq) KCl(aq) + MnCl2(aq) + H2O(l) + Cl2(g) Every reaction coeffisient of substances should be alphabetically aKMnO4(aq) + bHCl(aq) cKCl(aq) + dMnCl2(aq) + eH2O(l) +f Cl2(g) Then, change into mathematical equation form.

aKMnO4(aq) + bHCl(aq) cKCl(aq) + dMnCl2(aq) + eH2O(l) + fCl2 To equalize K atom : a = c (1) To equalize Mn atom : a = d (2) To equalize O atom : 4a = e (3) To equalize H atom : b = 2e (4) To equalize Cl atom : b = c + 2d + 2f (5) For instance : a=1 (1) a=c c=1 (2) a=d d=1 (3)4a=e (4) b=2e (5) b= c + 2d + 2f 8 – 3 = 2f 2f = 5 4x1=e b=2 x 4 8 = 1 + 2x1+ 2f f = 5/2 e = 4 b= 8 8 = 1 + 2 + 2f

X 2 aKMnO4(aq)+bHCl(aq) cKCl(aq)+dMnCl2(aq)+eH2O(l)+fCl2 1 8 5/2 1 4 1 2KMnO4(aq)+16HCl(aq) 2KCl(aq)+2MnCl2(aq)+8H2O(l)+5Cl2

Tentukan koefisien persamaan reaksi di bawah ini. N2 + H2 NH3 S + O2 SO3 SO2 + O2 SO3 H3PO4 + Ca(OH)2 Ca3(PO4)2 + H2O Al + H2SO4 Al2(SO4)3 + H2 P2O5 + Al(OH)3 AlPO4 + H2O NaOH + Cl2 NaCl + NaOCl2 + H2O