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ข้อคิดเห็นจากผู้ทรงคุณวุฒิจะแสดงในกรอบสีเขียว ส่วนข้อคิดเห็นหรือความเห็นจากผู้อื่นจะแสดงในกรอบปกติ
ข้อคิดเห็นที่
1: 1. NaCl or NaNO3 Dissolve the solid in water . Test with AgNO3 Solution NaCl (aq) + AgNO3 (aq) --- > AgCl ( white precipitate ) + NaNO3 (aq) NaNO3 (aq) + AgNO3 (aq) --- > No Reaction 2. CaSO4 or CaCO3 Test with HCl Solution CaSO4 (s) + 2 HCl (aq) --- > No reaction ; CaSO4 will slightly dissolve in the HCl Solution CaCO3 (s) + 2 HCl (aq) --- > CaCl2 (aq) + H2O + CO2 ( gas ) ___ Dissolution of Solid with Evolution of Gas 3. Mg(OH)2 or MgSO4 Test for solubility in water Mg(OH)2 is insoluble in water ; MgSO4 is soluble in water 4. Na2HPO4 or NaHCO3 Test with HCl Solution Na2HPO4 (s) + HCl (aq) --- > Dissolution of Solid ; No gas generated 2 NaHCO3 (s) + 2 HCl (aq) --- > 2 NaCl (aq) + H2O + CO2 ( gas ) ___ Dissolution of Solid with Evolution of Gas 5. NH4NO3 or KNO3 Test with NaOH Solution NH4NO3 (s) + NaOH (aq) --- > NaNO3 (aq) + NH3 ( gas which can turn moist Red litmus paper to Blue ) KNO3 (s) + NaOH (aq) --- > No reaction ; KNO3 will just dissolve 6. Zn(C2H3O2)2 or Zn(NO3)2 Adding dilute sulfuric acid Zn(C2H3O2)2 (s) + H2SO4 (aq) --- > ZnSO4 (aq) + 2 CH3COOH (aq) __ Vinegar odor Or test for Nitrate ( as oxidizing agent ) Zn(NO3)2 (s) + H2SO4 (aq) + KI (aq) --- > ZnSO4 (aq) + NO (g) + I2 ( aq ; brown color ) ____ equation not balanced 2 NO (g) + O2 --- > 2 NO2 ( Reddish-Brown Gas ) 7. ZnSO4 or MgSO4 Test with NaOH solution ZnSO4 >> Gel-Like Precipitate ; soluble in excess NaOH ZnSO4 (aq) + 2 NaOH (aq) --- > Zn(OH)2 (s) + 2 Na^+ (aq) + SO4^2- (aq) Zn(OH)2 (s) + 2 NaOH (aq) --- > Zn(OH)4^2- (aq) + 2 Na^+ (aq) MgSO4 >> Gel-Like Precipitate ; insoluble in excess NaOH MgSO4 (aq) + 2 NaOH (aq) --- > Mg(OH)2 (s) + 2 Na^+ (aq) + SO4^2- (aq) 8. CaCl2 or FeSO4 Dissolve the solid in water . Test with BaCl2 solution CaCl2 (aq) + BaCl2 (aq ) >> no reaction FeSO4 (aq) + BaCl2 (aq) --- > BaSO4 (s) + Fe^2+ (aq) + 2 Cl^- (aq) White Precipitate of BaSO4 ; insoluble in HCl [ Actually , CaCl2 is a white solid ; FeSO4 is a green solid . You can differentiate by just visual inspection ] 9. Zn(C2H3O2)2 or NH4C2H3O2 Dissolve the solid in water . Test with NaOH solution Zn(C2H3O2)2 (aq) + 2 NaOH (aq) --- > Zn(OH)2 (s) + 2 Na^+ (aq) + 2 C2H3O2^- (aq) Zn(OH)2 (s) + 2 NaOH (aq) --- > Zn(OH)4^2- (aq) + 2 Na^+ (aq) [ Zn(OH)2 precipitates and then dissolves in Excess NaOH NH4C2H3O2 (aq) + NaOH (aq) --- > NaC2H3O2 (aq) + NH3 ( gas which can turn moist Red litmus paper to Blue ) 10. CoCl2 or KBr Dissolve the solid in water . Test with concentrate HCl solution Co(H2O)6^2+ ( aq ; faint pink ) + 4 Cl^- (aq) --- > CoCl4^2- ( aq ; Blue Color ) + 6 H2O KBr (aq) + HCl (aq) --- > No reaction 11. KCl or KI Dissolve the solid in water . Test with CuSO4 solution CuSO4 (aq) + KCl (aq) --- > No reaction CuSO4 (aq) + 2 KI (aq) --- > CuI (s) + K2SO4 (aq) + I2 ( aq ; brown solution ) CuI is Copper (I) iodide 12. Na2SO3 or Na2SO4 Dissolve the solid in water . Test with Iodine solution Na2SO3 (aq) + I2 ( aq ; brown solution ) + H2O --- > Na2SO4 (aq) + 2 HI (aq) ___ Colorless Solution Na2SO4 (aq) + I2 ( aq ; brown solution ) --- > No reaction 13. NaCl or AlCl3.6H2O Dissolve the solid in water . Test with NaOH solution NaCl >> No reaction AlCl3 >> Gel-Like Precipitate ; soluble in excess NaOH AlCl3 (aq) + 3 NaOH (aq) --- > Al(OH)3 (s) + 3 Na^+ (aq) + 3 Cl^- (aq) Al(OH)3 (s) + NaOH (aq) --- > Al(OH)4^- (aq) + Na^+ (aq) 14. NaHSO4 or Na2SO4 Dissolve the solid in water . Add “ Methyl Orange Indicator Solution “ NaHSO4 (aq) is acidic solution >> Red Color Solution Na2SO4 (aq) is neutral solution >> Yellow Color Solution โดย: Real Chemist [5 ก.พ. 2559 01:38] |
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