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
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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.