What solution would form a precipitate when mixed with NaOH?
Mg(NO3)2 alkali earth metals tend to form insoluble hydroxides and oxides.
A solution of NaBr will form a precipitate when mixed with which of the following?
The answer is a) Pb(NO3)2 This is because in reacting NaBr with Pb(NO3)2, the following double displacement reaction occurs: NaBr + Pb(NO3)2 -----> NaNO3 + PbBr2 Based on predetermined 'Solubility Rules', we know that Pb does not 'mix' with Br, which means it will form a solid, or 'precipitate' in reacting. All the other possible compounds do, and thus are said to be 'soluble' with one another. Lead nitrate is the only correct answer.
Which of the following solutions will form a precipitate when added to (NH4)2S?
Joshua is almost right. Ag₂S is very insoluble and will precipitate, (Ksp =1.0 x 10⁻⁴⁹). However, the Ksp for CaS is not so small, Ksp =8 x 10⁻⁶. At first, it seems like this is pretty small, but that ignores something important. The NH₄⁺ ion is more acidic than HS⁻; its pKa is 14 - pKb for NH₃ (pKb = 4.75) For H₂S, pKa₁ = 7.04, pKa₂ = 11.96 For NH₄⁺ pKa = 9.25 Write out some equations from this information: S²⁻ + H₃O⁺ ⇌ HS⁻ + H₂O ====> K = 1/Ka₂ = 10¹¹˙⁹⁶ NH₄⁺ + H₂O ⇌ NH₃ + H₃O⁺ ====> Ka = 10⁻⁹˙²¹ ––––––––––––––––––––––––––––––––––––––... S²⁻ + NH₄⁺ ⇌ NH₃ + HS⁻ ==> Keq = K•Ka = 10²˙⁷¹ = 512 In words, the NH₄⁺ ion protonates most of the S²⁻ when you dissolve (NH₄)₂S to make an aqueous solution. That suppesses the sulfide concentration enough that CaS won't precipitate out unless the Ca²⁺ gets fairly high. (That's how pH is used to control sulfide concentration in qualitative analysis ion separation schemes - in acidic solution the sulfide concentration is quite low and only the most insoluble sulfide salts precipitate out. There's a 2:1 excess of NH₄⁺ ion compared to S²⁻ so in (NH₄)₂S you have the acidic NH₄⁺ ion, and there are enough available protons to convert most of the S²⁻ into HS⁻.)
Which of the following (aq) solutions would perform a precipitate when mixed with NaOH?
e. Mg(NO3)2. The precipitate would be Mg(OH)2. That's why you have to shake a bottle of milk of magnesia (Mg(OH)2) since the Mg(OH)2 tends to settle out, even though it is somewhat suspended.
Which of the following aqueous solutions would form a precipitate when mixed with NaOH?
A
How do I determine whether a precipitate will form when mixing two solutions?
You have to look at all possible combinations of the ions present, and see whether any of those combinations result in an insoluble compound. If so, that compound will precipitate out of solution. For example, if you mix silver nitrate solution with sodium chloride solution, the possible combinations are: sodium chloride sodium nitrate silver chloride silver nitrate Of these possible combinations, silver chloride is an insoluble compound. The other three are all soluble in water. Therefore if you mix these two solutions, white silver chloride will precipitate out of the solution.
Which of the following aqueous solutions should form a precipitate with aqueous Fe(NO3)3?
K2SO4 would because Fe2(SO4)3 is a blue precipitate.
Would you expect to observe a precipitate from the reaction of calcium chloride with silver nitrate?
Yes, because silver chloride is insoluble in water. 2AgNO3+CaCl2->2AgCl+Ca(NO3)2. In the very beggining of the reaction, when there are Ag+, NO3-, Ca+ and Cl- ions dissolved in water, you should ask yourself if there is any salt that can form from these ions that would not be soluble in water. If the answer is yes, that salt will precipitate out of the solution.