Ch.16 - Aqueous Equilibrium WorksheetSee all chapters
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Ch.1 - Intro to General Chemistry
Ch.2 - Atoms & Elements
Ch.3 - Chemical Reactions
BONUS: Lab Techniques and Procedures
BONUS: Mathematical Operations and Functions
Ch.4 - Chemical Quantities & Aqueous Reactions
Ch.5 - Gases
Ch.6 - Thermochemistry
Ch.7 - Quantum Mechanics
Ch.8 - Periodic Properties of the Elements
Ch.9 - Bonding & Molecular Structure
Ch.10 - Molecular Shapes & Valence Bond Theory
Ch.11 - Liquids, Solids & Intermolecular Forces
Ch.12 - Solutions
Ch.13 - Chemical Kinetics
Ch.14 - Chemical Equilibrium
Ch.15 - Acid and Base Equilibrium
Ch.16 - Aqueous Equilibrium
Ch. 17 - Chemical Thermodynamics
Ch.18 - Electrochemistry
Ch.19 - Nuclear Chemistry
Ch.20 - Organic Chemistry
Ch.22 - Chemistry of the Nonmetals
Ch.23 - Transition Metals and Coordination Compounds

Solution: In which solution(s) will a precipitate form? I. 0.00090 g of Na 2CrO 4 (molar mass = 162.0 g/mol) is added to 225 mL of 0.00019 M AgNO 3. Ksp Ag 2CrO 4 = 1.1 x 10 -12 II. 0.100L of 0.0015 M MgCl 2 and 0.200L of 0.012 M NaF. Ksp MgF 2 = 3.7 x 10 -8 a. I - no; II - nob. I - yes; II - noc. I - no; II - yesd. I - yes; II - yes

Problem

In which solution(s) will a precipitate form? 

I. 0.00090 g of Na 2CrO 4 (molar mass = 162.0 g/mol) is added to 225 mL of 0.00019 M AgNO 3. Ksp Ag 2CrO 4 = 1.1 x 10 -12 

II. 0.100L of 0.0015 M MgCl 2 and 0.200L of 0.012 M NaF. Ksp MgF 2 = 3.7 x 10 -8 

a. I - no; II - no

b. I - yes; II - no

c. I - no; II - yes

d. I - yes; II - yes

Solution

We’re being asked to determine which precipitate will form given in the given solutions for MgF2 and Ag2CrO4


For this, we need to compare the reaction quotient (Q) vs. the solubility product constant (Ksp). Recall that when:

• Q > Ksp: the solution is supersaturated and a precipitate will form. Reactants are favored.

• Q = Ksp: the solution is at equilibrium and no precipitate will form.

• Q < Ksp: the solution is unsaturated and no precipitate will form. Products are favored.


In this case, we need to follow each step:

Step 1. Setup the reaction quotient expression

Step 2. Determine the concentrations of each species involved in the precipitation

Step 3. Calculate for Q

Step 4. Compare it to Ksp

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