Solubility rules:
Solubility rules are sets of rules predicting the solubility combinations of different cations and anions and on mixing with each other.
(aq) represents soluble combinations
(s) represents insoluble combinations
(d) represents decomposition (complex reactions)
Density of water Sample Questions:
Question 1: Based on the solubility rules, which one of the following compounds should be insoluble in water?
a) Na2So4
b) CuSO4
c) BaSO4
d) MgSO4
Answer: Option c) BaSO4
Explanation: Among the given options, BaSO4 insoluble in water. Most sulfate salts are soluble. Na2So4 ,CuSO4 , MgSO4 are all soluble in water.
Question 2: Which one of the following salts are mostly insoluble in water?
a) Nitrates
b) Sulfates
c) Carbonates
d) Halides
Answer: Option c) Carbonates
Explanation: Carbonates are frequently insoluble in water. Nitrates, sulfates, halides all are mostly soluble in water.
Question 3: Which of the following salt is slightly soluble in water?
a) Chromates
b) Hydroxide
c) Sulfate
d) Nitrate
Answer: Option b) Hydroxide
Explanation: Most hydroxides are insoluble in water, But some like calcium hydroxide and barium hydroxide are slightly soluble.
Question 4: Which of the following are always soluble in water?
a) Alkali metals
b) Fluorides
c) Sulfates
d) Chromates
Answer: Option a) Alkali metals
Explanation: Salts containing Group 1 elements also known as alkali metals (Li+, Na+, K+, Cs+, Rb+) are soluble in water. Rest of the mentioned salts have exceptions.
Question 5: Which of these substances is likely to form a precipitate?
a) Nacl
b) AgBr
Answer: Option b) AgBr
Explanation: Bromides are usually soluble but salts of silver are mostly insoluble. AgBr is insoluble and forms precipitate.
Question 6: There will be precipitates formed in the following reaction
2NaOH + K2CrO4 → KOH+Na2CrO4
a) True
b) False
Answer: Option b) False
Explanation: KOH is hydroxide of alkali metal potassium. Salts of alkali metals are soluble and hence KOH is soluble. also is a salt of alkali metal Na and hence it is soluble too. Both the products are soluble. Therefore, no precipitate will be formed in this reaction
Question 7: Which of the following salts is insoluble in water?
a) Sodium phosphate
b) Barium hydroxide
c) Magnesium carbonate
d) Potassium nitrate
Answer: Option c) Magnesium carbonate
Explanation: Carbonate salts are usually insoluble in water with few exceptions like when carbonate is paired with an alkali metal. Magnesium carbonate is considered an insoluble salt.
Question 8: Which of the following statements is incorrect according to solubility rules?
a) Ammonium salts are considered soluble
b) Salts containing a nitrate ion are considered soluble
c) Phosphate salts are generally considered soluble
d) Ionic compounds with halogens are generally soluble
Answer: Option c) Phosphate salts are generally considered soluble
Explanation: According to solubility rules the salts containing alkali metals, nitrate ions, ammonium ions are considered soluble. Phosphates, on the other hand, are generally considered insoluble, unless it is paired with an alkali metal or ammonium ion.
Question 9: Substances for which pure water would not be an efficient solvent are?
a) Those that have high charge densities
b) Those that have large dipole moments
c) Those with evenly dispersed electrons
d) Those that tend to form hydrogen bonds
Answer: Option c) Those with evenly dispersed electrons
Explanation: Water is a polar molecule, it dissolves substances having electrostatic charge due to electronic arrangement. Evenly dispersed electrons means a nonpolar molecule which will not dissolve in water.
Question 10: Which of the following molecules is insoluble?
a) Mg(NO3)2
b) AgCl
c) KBr
d) AgNO3
Answer: AgCl
Explanation: According to solubility rules, alkali metal salts and ammonium salts are soluble, all nitrates, acetates, and perchlorates are soluble and mercury, lead, and silver salts are insoluble.
Therefore, AgCl is insoluble.
Frequently Asked Questions
What are solubility rules?
Following are the solubility rules for ionic solids-
Salts containing Group 1 elements (Li+,Na+,K+,Cs+,Rb+)are soluble .
Salts containing nitrate ion (NO3-) are mostly soluble.
Salts containing Cl-, Br-, I-are generally soluble. However, halide salts of Ag+,Pb+,(Hg2)2+. Thus, AgCl, PbBr2, Hg2Cl2are insoluble.
Most silver salts are insoluble. AgNO3,Ag(C2H3O2) are exceptions.
Most sulfate salts are soluble, with few exceptions CaSO4, BaSO4,PbSO4,AgSO4,SrSO4 .
Most hydroxide salts are only slightly soluble, like the hydroxide salts of Group 2 elements (Ca, Sr, and Ba). But, The hydroxide salts of Group 1 elements are soluble.
Hydroxide salts of transition metals and Al3+ are insoluble. Thus, Fe(OH)3,Al(OH)2, Co(OH)2are not soluble.
Most of the sulfides of transition metals are highly insoluble.
Carbonates are frequently insoluble.
Chromates are frequently insoluble. Examples include PbCrO4and BaCrO4
Phosphates like Ca3(PO4)2and Ag3PO4 are frequently insoluble.
Fluorides such as BaF2, MgF2and PbF2 are frequently insoluble.
Based on the solubility rules, which one of the following compounds should be insoluble in water?
a) Na2So4
b) CuSO4
c) BaSO4
d) MgSO4
Among the given options, BaSO4is insoluble in water. Most sulfate salts are soluble, but their are some exceptions like CaSO4, BaSO4,PbSO4,AgSO4,SrSO4 .
How to remember the solubility rules?
There are different ways to remember the solubility rules. One such way is using the pattern NAG SAG. Each letter represents soluble molecules.
N: Nitrates (NO3-)
A: Acetates (CH3COO-)
G: Group 1 alkali metals (Li+, Na+, etc)
S: Sulfates (SO4-2)
A: Ammonium ions (NH4+)
G: Group 17 nonmetals (F-, Cl-, Br-, I-, etc.)
Write PMS to represent the first exception. P stands for Pb+2 (lead). M stands for Mercury (Hg2+2). S stands for Silver (Ag+). These three ions are never soluble with sulfate group and group 17 nonmetals.
Write Castro Bear to represent the second exception. Castro Bear stands for Calcium (Ca+2), Strontium (Sr+2), and Barium (Ba+2). These three ions are not soluble with sulfates.
How do you use a solubility chart?
Solubility chart is a chart with a list of ions, representing what will be produced on combinations of different cations with anions and the solubility of the ions on mixing with each other.
Using a solubility chart the combination result of two different ions can be predicted.
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