SCH 3U

Unit: Chemical Reactions

Solubility (pg. 136)

·  A solution is homogeneous (looks the same throughout) mixture of a solute dissolved in a solvent. For example, when the solute, sodium chloride, dissolves in the solvent, water, a solution is formed.

·  When a solute forms a solution with water as the solvent, we call it an “aqueous” solution and indicate this with the (aq) designation for physical state. For example, the solution of sodium chloride and water described above is written as NaCl(aq).

·  Every solute has its own solubility in a given solvent. This means that each solute has a maximum quantity that will dissolve in a given solvent under a given set of conditions. We can get a qualitative idea about whether or not a precipitate of the solute could form by using a solubility table like the one in Table 1 page 137 (reproduced below). To determine the solubility of a compound using this table, find the anion in the compound along the top of the table first. Then find the appropriate cation. When you have identified both the anion and the cation, read across the table to the left to determine whether the substance has a high solubility or a low solubility. Those substances with low solubility will not dissolve very well in water at SATP (Standard Ambient Temperature and Pressure; 20oC and 100 kPa.)

Table 1: Solubility of Ionic Compounds in Water at SATP

(or use Table 1 page 137, Nelson)

ANIONS
Cl1-, Br1-, I1- / S2- / OH1- / SO42- / CO32-, PO43-, SO32- / C2H3O21- / NO31-
C
A
T
I
O
N
S / High Solubility (aq)
≥0.1 / Most / Group 1, NH41+ and Group 2 / Group 1, NH41+, Sr2+, Ba2+, Tl1+ / Most / Group 1, NH41+ / Most / All
All Group 1 compounds, including acids, and all ammonium cmpds. are assumed to have high solubility in water.
Low Solubility (s)
≤0.1 at / Ag1+, Pb2+, Tl1+, Hg22+, Hg1+
Cu1+ / Most / Most / Ag1+, Pb2+, Ca2+,
Ba2+, Sr2+, Ra2+ / Most / Ag1+ / none

Practice

Do page 138 #1, 2, 3

Double Displacement (Metathesis) Reactions (pg. 136 – 144, Nelson)

·  follow the general format: AB + CD à AD + CB where A and C are cations and B and D are anions (Recall that the cation is always written first in the formula for an ionic compound.)

·  A double displacement reaction is likely to proceed if one of the following occurs:
a) one of the products is a precipitate (a new, low solubility solid formed during the chemical
reaction that, eventually, settles to the bottom of the reaction container)
In order to determine whether or not a precipitate may form, it is necessary to use a
solubility table like Table 1 on page 137 to help determine the likely physical state of each
product.
example: CaCl2(aq) + Na2CO3(aq) à CaCO3(s) + 2 NaCl(aq)

b) one of the products is a gas (The gases most likely to form are H2S, CO2, SO2, NH3 .)
example: Na2S(a) + 2 HCl(aq) à 2 NaCl(aq) + H2S(g)

[Note: We will not see too many examples of this type of double displacement reaction in
grade 11 chemistry.]

c) the reactants are an acid (containing H1+(aq)) and a base (containing OH1-(aq)) which
undergo a neutralization reaction to produce a salt (a metal cation and an anion) and liquid
water
example: Mg(OH)2(aq) + 2 HCl(aq) à MgCl2(aq) + 2 H2O(l)

base acid salt water

Practice
1. Each of the chemical equations below is presented as a double displacement reaction. Predict whether or not each reaction will proceed as written. If is likely to proceed, complete a balanced equation for the reaction. Be sure to show the physical states of all reactants and products. If the reaction will not proceed, write NR (no reaction) to the right of the arrow.
a)  CuSO4(aq) + NaNO3(aq) à d) aqueous silver nitrate + aqueous magnesium chloride à
b)  (NH4)2CO3(aq) + CaCl2(aq) à e) aqueous iron(II) sulfate + aqueous sodium acetate à
c)  NaOH(aq) + HCl(aq) à f) aqueous sulfuric acid + aqueous potassium hydroxide à
2.  Do #7. 10, 11 page 142.


The following has been written for the McGraw – Hill book.


SCH 3U

Unit 2: Chemical Reactions

Unit Test Study Guide

We are aiming to have a unit test on chemical reactions on Wednesday 9 November 2011.
Note the date change – this is to accommodate students who want extra time. (They can begin before lunch ends and write into the period.) Note also, that we will begin working on Unit 3 before the unit test next week occurs.

1.  Be sure you are familiar with the following terms.

Synthesis / Decomposition / Combustion
- incomplete and complete / Single displacement
Double displacement / Activity series / Solublility table / Word equation
Skeleton equation / Balanced chemical equation / Solute / Solvent
Solubility / Acid-base neutralization reaction / Precipitate / Acidic, basic

2.  Be sure you can do the following tasks.
a) Recognize synthesis, decomposition, combustion (incomplete and complete), single
displacement and double displacement reactions.
b) Predict the products (if given the reactants) of chemical reactions that may be synthesis,
decomposition, combustion (incomplete and complete), single displacement or double
displacement (including acid-base neutralization reactions)
b) Balance chemical equations.
c) Write a word equation, skeleton equation and/or a balanced chemical equation from a
description of a chemical reaction that include physical states of reactants and products.
d) Use an activity series to predict whether or not a given single displacement reaction will
occur.
e) Use a solubility table to predict whether or not a given ionic compound is soluble and/or
whether or not a double displacement reaction is a possibility.
f) Explain the difference between complete and incomplete combustion reactions.
g) Predict the chemical reactions that result in the formation of acids and bases from metal
oxides and non-metal oxides (e.g. Calcium oxide reacts with water to produce a basic
solution and carbon dioxide gas reacts with water to produce an acidic solution.)

3.  Practice Problems for Review

Reaction Type / Questions to Try
Synthesis / Page 209 – 213 #12; pages 214 – 215 #1, 13
Decomposition / Page 209 – 213 #13, 14
Combustion / Page 209 – 211 #3, 7, 24
Single displacement / Page 209 – 211 #4, 5, 6, 20, 30; pages 214 – 215 #4, 21, 22, 23
Double displacement / Page 209 #2, 8, 9, 31, 32, 33, 34, 43; pages 214 -215 #10, 14
General / Page 209 - 213 #1, 11, 16, 17, 18, 19, 25, 26, 27, 28, 29, 42, 54
Pages 214 – 215 #3, 5, 7, 9, 11, 12, 15, 17, 18, 19, 20

4.  General Review of the Five Types of Reactions Studied in this Unit (Nelson)

Page 146 #3, 4, 5, 6

5.  Table 1: Solubility of Ionic Compounds in Water at SATP

(page 137 in text)

Anions
Cl1-, Br1-, I1- / S2- / OH1- / SO42- / CO32-, PO43-, SO32- / C2H3O21- / NO31-
C
A
T
I
O
N
S / High Solubility (aq)
≥0.1 / Most / Group 1, NH41+ and Group 2 / Group 1, NH41+, Sr2+, Ba2+, Tl1+ / Most / Group 1, NH41+ / Most / All
All Group 1 compounds, including acids, and all ammonium cmpds. are assumed to have high solubility in water.
Low Solubility (s)
≤0.1 at / Ag1+, Pb2+, Tl1+, Hg22+, Hg1+
Cu1+ / Most / Most / Ag1+, Pb2+, Ca2+,
Ba2+, Sr2+, Ra2+ / Most / Ag1+ / none

Activity Series for Metals

Activity Series for Halogens

Halogen / Reactivity
fluorine / Most reactive

Least reactive
chlorine
bromine
iodine