SOLUBILITY RULES, GAS FORMATION AND QUALITATIVE ANALYSIS OF IONSA Recitation and Review in Chemistry 3PSHS-CVC

QUESTION NO. 1

Which of the following is insoluble?a. Hg(NO3)2

b. HgBr2

c. Hg(OH)2

d. HgSO4

Answer: c. Hg(OH)2

QUESTION NO. 2

Which of the following does not belong to the group?a. Pb(NO3)2

b. PbCO3

c. Pb3(PO4)2

d. PbSAnswer: a. Pb(NO3)2 - soluble

QUESTION NO. 3

Which of the following mixtures will produce a gas?a. H2SO4 (aq) + Ca(OH)2 (aq)b. Na2CO3 (aq) + HCl (aq)c. NH4Cl (aq) + HNO3 (aq)d. Na2SO4 (aq) + HClO4 (aq)Answer: b. Na2CO3 (aq) + 2 HCl (aq) → NaCl (aq) + CO2 (g) + H2O (l)

QUESTION NO. 4

Which of the following mixtures will result to a precipitate upon mixing?a. HBr (aq) + Hg(NO3)2 (aq)b. Na2CO3 (aq) + KI (aq)c. NH4Cl (aq) + SrCl2 (aq)d. Na2SO4 (aq) + AgNO3 (aq)Answer: d. Na2SO4 (aq) + 2AgNO3 (aq) → 2NaNO3 (aq) + Ag2SO4 (s)

QUESTION NO. 6

Predict the stable products (including their phases) of the reaction between (NH4)2SO4 (aq) and Mg(OH)2 (aq).

Answer: NH3 (g) + H2O (l)

QUESTION NO. 7

What cation is responsible for the color of this solution?

Answer: Chromium (III) or Cr3+

QUESTION NO. 8

What cation is responsible for the color of this solution?

Answer: Nickel (II) or Ni2+

QUESTION NO. 9

What cation is responsible for the color of this solution?

Answer: Cupric, Copper (II) or Cu2+

QUESTION NO. 10

What anion is responsible for the color of this solution?

Answer: Dichromate or Cr2O72-

QUESTION NO. 11

What hydroxide precipitate is formed as depicted in the figure on the right?

Answer: Co(OH)2 (s)

QUESTION NO. 12

When NaOH is added to an orange colored cation solution, a precipitate is formed as depicted in the figure on the right. What precipitate is it?

Answer: Fe(OH)3 (s)

QUESTION NO. 13

What cation is responsible for the color of this flame?

Answer: Sodium or Na+

QUESTION NO. 14

What cation is responsible for the color of this flame?

Answer: Potassium or K+

QUESTION NO. 15

What cation is responsible for the color of this flame?

Answer: Strontium or Sr2+

QUESTION NO. 17

Co2+ is responsible for the color of the right flame. What cation is responsible for the color of the flame onthe left?

Answer: Copper (II) or Cu2+

Co2+?

QUESTION NO. 18

What cation is responsible for the color of the middle flame in the picture below?

Answer: Calcium (II) orCa2+

Sr2+ Na+?

QUESTION NO. 16

When an unknown solution forms a precipitate with HCl which dissolves with excess NH3, what cation is surely present in the solution?

Answer: Silver (I) or Ag+

QUESTION NO. 18

When NaSCN or NH4SCN was added to an unknown solution, the result is shown on the picture. What cation is surely present in the unknown solution?

Answer: Ferric or Fe3+

QUESTION NO. 19

The picture below depicts the confirmatory test for a certain cation. HCl was initially added forming the white ppt. Then when NH3 was added to the ppt., it turned black.What is the cation responsiblefor these results?Answer: Mercury (I) or Hg2

2+

QUESTION NO. 20The addition of NaOH to an unknown cation resulted to a light green precipitate as depicted in the figure on the right? What cation is surely present in the solution?

Answer: Ni2+

QUESTION NO. 21

Which hydroxide precipitate is soluble upon the addition of excess NaOH?

a. Cr(OH)3

b. Fe(OH)3

c. Co(OH)3

d. Ni(OH)3

Answer: H+ from a strong acid

QUESTION NO. 22An unknown cation solution was tested with HCl and no ppt formed. When either acidic H2S or basic (NH4)2S were added, still NVRs were observed. The addition of Na2CO3 resulted to the formation of a ppt. The solution yielded a colorless flame. With excess NaOH, the result is depicted by the picture shown. Thus…Groups I to III cations are surely absent in the solution. True of False?Answer: True

QUESTION NO. 23An unknown cation solution was tested with HCl and no ppt formed. When either acidic H2S or basic (NH4)2S were added, still NVRs were observed. The addition of Na2CO3 resulted to the formation of a ppt. The solution yielded a colorless flame. With excess NaOH, the result is depicted by the picture shown. Thus…A Group IV (Barium or carbonate grp.) is surely present in the solution.Answer: True

QUESTION NO. 24An unknown cation solution was tested with HCl and no ppt formed. When either acidic H2S or basic (NH4)2S were added, still NVRs were observed. The addition of Na2CO3 resulted to the formation of a ppt. The solution yielded a colorless flame. With excess NaOH, the result is depicted by the picture shown. Thus…A Group V cation (soluble group)is surely absent in the solution.True or False? Answer: False

QUESTION NO. 25An unknown cation solution was tested with HCl and no ppt formed. When either acidic H2S or basic (NH4)2S were added, still NVRs were observed. The addition of Na2CO3 resulted to the formation of a ppt. The solution yielded a colorless flame. With excess NaOH, the result is depicted by the picture shown. Thus…NH4

+ is surely present in the sol’n.True or False?Answer: True

QUESTION NO. 26An unknown cation solution was tested with HCl and no ppt formed. When either acidic H2S or basic (NH4)2S were added, still NVRs were observed. The addition of Na2CO3 resulted to the formation of a ppt. The solution yielded a colorless flame. With excess NaOH, the result is depicted by the picture shown. Thus…K+ is surely present in the solution.True or False?Answer: False

QUESTION NO. 27An unknown anion solution was tested concentrated H2SO4 and a gas was produce. When AgNO3 was added into the solution a yellow precipitate was produced.Thus…Chromate or CrO4

2- is surely present in the solution.True or False?

Answer: False

QUESTION NO. 28An unknown anion solution was tested concentrated H2SO4 and a gas was produce. When AgNO3 was added into the solution a yellow precipitate was produced.Thus…I- is surely present in the solution.True or False?

Answer: True

QUESTION NO. 29What reagent is required to bring about the following chemical change?

Answer: H+ from a strong acid

?

QUESTION NO. 30

Answer: dimethylglyoxime or DMG

?excess

NH3NH3

What reagent is required to bring about the result of the last step in the confirmatory test for Ni2+?

QUESTION NO. 31What score did your group get in the recitation (quiz bee)?

Please write it on your slates.

God bless you on the quiz tomorrow.