Solubility Guidelines for Compounds in Aqueous Solutions

Transcription

1 Solubility Guidelines for Compounds in Aqueous Solutions It is very important that you know these guidelines and how to apply them in reactions. 1) Common inorganic acids and low-molecularweight organic acids are water soluble. 2) All common compounds of the Group IA metal ions and the ammonium ion are water soluble. Li, Na, K, Rb, Cs, and NH NH 4

2 Aqueous Solutions: An Introduction 3) Common nitrates, acetates, chlorates, and perchlorates are water soluble. NO - 3, CH 3 COO -, ClO - 3, and ClO - 4 4) Common chlorides are water soluble. Exceptions AgCl, Hg 2 Cl 2,& PbCl 2 Common bromides and iodides behave similarly to chlorides. Common fluorides are water soluble. Exceptions MgF, CaF 2 2, SrF 2, BaF 2, and PbF 2

3 Aqueous Solutions: An Introduction 5) Common sulfates are water soluble. Exceptions PbSO, BaSO 4 4, & HgSO 4 Moderately soluble CaSO, SrSO 4 4,& Ag 2SO 4 6) Common metal hydroxides are water insoluble. Exceptions LiOH, NaOH,, KOH, RbOH & CsOH Common bromides and iodides behave similarly to chlorides. Common fluorides are water soluble. Exceptions MgF 2, CaF 2, SrF 2, BaF 2, and PbF 2

4 Aqueous Solutions: An Introduction 7) Common carbonates, phosphates, and arsenates are water insoluble. CO 3, PO 3-4, & AsO AsO 4 3- Exceptions- IA metals and NH Moderately soluble MgCO 3 NH 4 plus Ca to Ba 8) Common sulfides are water insoluble. Exceptions IA metals and NH NH 4 plus IIA metals

5 Ionic Equations There are three ways to write reactions in aqueous solutions. 1. Molecular equation Show all reactants & products in molecular or ionic form Zn (s) CuSO 4(aq) ZnSO 4(aq) 2. Total ionic equation Show the ions and molecules as they exist in solution Zn (s) Cu 2 SO Zn 2 SO Cu ( aq) 4( aq) ( aq) 4( aq) (s) (s) Cu

6 Ionic Equations 3. Net ionic equation Shows ions that participate in reaction and removes spectator ions. Spectator ions do not participate in the reaction. Spectator ions in < > s. Zn (s) Cu 2 SO Zn 2 SO ( aq) 4( aq) ( aq) 4( aq) (s) Cu Zn (s) Cu 2 Zn 2 Cu ( aq) ( aq) (s)

7 Molecular equation 2 HCl Na SO 2 NaCl H O (aq) 2 3(aq) (aq) 2 SO ( l) 2( g) Total ionic reaction 2 H 1 2 Cl 1-2 Na 1 ( aq) ( aq) ( aq) 3( aq) 2 Na Net ionic reaction 1 1 SO 2 Cl 1- H O SO ( aq) ( aq) 2 ( l) 2( g) 2 H SO H O ( aq) 3( aq) 2 ( l) 2( g) SO

8 Molecular equation Ca(OH) 2 2 HNO Ca(NO (aq) 3(aq) 3) 2 H 2(aq) 2O( l) Total ionic equation Ca 2 2 OH - 2 H 2 NO - Ca ( aq) ( aq) ( aq) 3( aq) ( aq) 3( aq) 2 ( l) Net ionic equation 2 OH - OH ( aq ) ( aq ) - 2 H or better H H 2 2 H O ( aq ) ( aq ) 2 ( l ) 2 2 NO O ( l ) - 2 H O

9 Molecular equation Ca(NO 3) K 2(aq) 2CO 2 KNO CaCO 3(aq) 3(aq) 3(s) Total ionic reaction Ca 2 2 NO - 2 K ( aq) 3( aq) ( aq) 3( aq) Net ionic reaction Ca 2 CO 2 K CO 2 NO - CaCO ( aq) 3( aq) 3( s) CaCO ( aq) 3( aq) 3(s)

10 Molecular equation 3CaCl ( ) 4 2(s) 2 2 Na (aq) 3PO 6 NaCl 4(aq) (aq) Ca3 PO Total ionic reaction 3Ca 2 6Cl 1-6 Na 1 ( aq) ( aq) ( aq) 4( aq) 6 Na Net ionic reaction Ca 2 PO 2 PO 6Cl 1-3- Ca PO ( ) ( aq) ( aq) 3 4 2() s Ca PO ( ) ( aq ) 4( aq ) 3 4 2() s

11 Oxidation Numbers Guidelines for assigning oxidation numbers. 1. The oxidation number of any free, uncombined element is zero. 2. The oxidation number of an element in a simple (monatomic) ion is the charge on the ion. 3. In the formula for any compound, the sum of the oxidation numbers of all elements in the compound is zero. 4. In a polyatomic ion, the sum of the oxidation numbers of the constituent elements is equal to the charge on the ion.

12 Oxidation Numbers 5. Fluorine has an oxidation number of 1 in its compounds. 6. Hydrogen, H, has an oxidation number of 1 unless it is combined with metals, where it has the oxidation number -1. Examples LiH, BaH 2 7. Oxygen usually has the oxidation number -2. Exceptions: In peroxides O has oxidation number of 1. Examples - H 2 O 2, CaO 2, Na 2 O 2 In OF 2 : O has oxidation number of 2.

13 Oxidation Numbers 8. Use the periodic table to help with assigning oxidation numbers of other elements. a. IA metals have oxidation numbers of 1. b. IIA metals have oxidation numbers of 2. c. IIIA metals have oxidation numbers of 3. There are a few rare exceptions. d. VA elements have oxidation numbers of 3 in binary compounds with H, metals or NH 4. e. VIA elements below O have oxidation numbers of 2 in binary compounds with H, metals or NH 4.

14 Assign oxidation numbers to the element specified in each group of compounds N in NaNO 3 Sn in K 2 Sn(OH) 6 P in H 3 PO 4 S in SO 3 Cr in Cr 2 O 7

15 Assign oxidation numbers to the element specified in each group of compounds N in NH 3 O in Na 2 O 2 Fe N in N 2 O 4

16 Assign oxidation numbers to the element specified in each group of compounds P in H 4 P 2 O 7 Hg in Hg 2 Cl 2 Li in LiH S in S 4 O 6