Chemistry
Mention the colour changes observed when the following indicators are added to acids:
(i) Alkaline phenolphthalein solution.
(ii) Methyl orange solution
(iii) Neutral litmus solution
Acids Bases Salts
Answer
(i) Pink solution becomes colourless.
(ii) Orange solution changes to pink colour.
(iii) Purple solution changes to red colour.
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Related Questions
BASES — Ions present in bases a. Alkali — dissociates yielding hydroxyl ions 16. Sodium hydroxide NaOH [aq.] ⇌ …………… + …………… 17. Ammonium hydroxide NH4OH [aq.] ⇌ …………… + …………… b. Classification 18. Monoacidic base [Acidity = 1 ] KOH [aq.] ⇌ …………… + …………… 19. Diacidic base [Acidity = 2] Cu(OH)2 [aq.] ⇌ …………… + …………… c. Preparation of bases 20. From metals Na + O2 ⟶ …………… 21. From metallic oxides and metals K2O + H2O ⟶ …………… K + H2O ⟶ …………… + …………… 22.From salts AlCl3 + NaOH ⟶ …………… + …………… ↓ FeSO4 + NaOH ⟶ …………… + …………… ↓ 23. By thermal decomposition ZnCO3 ⟶ …………… + …………… [g] Pb(NO3)2 ⟶ …………… + ……………[g] + ………….. [g] c. Properties of bases 24. Neutralizes acids PbO + HNO3 ⟶ …………… + …………… Fe(OH)2 + HCl ⟶ …………… + …………… Reaction with 25. Metallic salt solution CuCl2 + NaOH ⟶ …………… + …………… ↓ FeCl3 + NaOH ⟶ …………… + …………… ↓ 26. Ammonium salts NH4Cl + NaOH ⟶ …………… + …………… + …………… [g] NH4Cl + Ca(OH)2 ⟶ …………… + …………… + …………… [g] SALTS — Ions present in salts 27a. Normal salt [formation] NaOH [excess] + H2SO4 ⟶ …………… + H2O 27b. Acid salt [formation] NaOH [insufficient] + H2SO4 ⟶ …………… + H2O Preparation of salts — General methods Direct combination — Synthesis 28. Iron and Chloride — salt iron [III] Chloride Fe + Cl2 ⟶ …………… 29. Zinc and sulphur — salt zinc sulphide Zn + S ⟶ …………… Displacement — Action of dilute acid on active metals 30. Iron — salt iron [II] sulphate Fe + H2SO4 ⟶ …………… + …………… [g] 31. Zinc — salt zinc sulphate Zn + H2SO4 ⟶ …………… + …………… [g] 32. Magnesium — salt magnesium chloride Mg + HCl ⟶ …………… + …………… [g] Precipitation — by double decomposition of two salt solutions 33. Lead nitrate and sodium chloride Pb(NO3)2 + NaCl ⟶ …………… + …………… ↓ 34. Calcium chloride and sodium carbonate CaCl2 + Na2CO3 ⟶ …………… + …………… ↓ Neutralization — Action of dilute acid on insoluble base 35. Oxide — salt copper sulphate CuO + H2SO4 ⟶ …………… + …………… 36. Hydroxide — salt copper sulphate Cu(OH)2 + H2SO4 ⟶ …………… + …………… Neutralization — [Titration] Action of dilute acid on an alkali 37. Hydroxide — salt sodium chloride NaOH + HCl ⟶ …………… + …………… 38. Hydroxide — salt ammonium chloride NH4OH + HCl ⟶ …………… + …………… Action of dilute acid on carbonate & bicarbonate 39. Carbonate — salt lead nitrate PbCO3 + HNO3 ⟶ …………… + …………… + …………… [g] 40. Carbonate — salt copper chloride CuCO3 + HCl ⟶ …………… + …………… + …………… [g] 41. Bicarbonate — salt potassium sulphate KHCO3 + H2SO4 ⟶ …………… + …………… + …………… [g] Which of the following hydroxides is not an alkali — [Choose from the choices A, B, C and D]
(A) ammonium hydroxide
(B) calcium hydroxide
(C) copper hydroxide
(D) sodium hydroxide
Complete the blanks from the list given:
Ammonia, Ammonium, Carbonate, Carbon dioxide, Hydrogen, Hydronium, Hydroxide, Precipitate, Salt, Water.
A solution X turns blue litmus red, so it must contain (i) …………… ions; another solution Y turns red litmus blue and therefore, must contain (ii) …………… ions. When solutions X and Y are mixed together the products will be a (iii) …………… and (iv) …………… . If a piece of magnesium were put into solution X, (v) …………… gas would be evolved.