170 likes | 306 Views
Chapter 4. Reactions In Aqueous Solutions. A homogeneous mixture of two or more substances. When we dissolve a substance in a liquid, The substance is the solute and the liquid is the solvent. What is a solution?. When the solvent is water, The solution is an aqueous solution.
E N D
Chapter 4 Reactions In Aqueous Solutions
A homogeneous mixture of two or more substances • When we dissolve a substance in a liquid, • The substance is the solute • and the liquid is the solvent. What is a solution? • When the solvent is water, • The solution is an aqueous solution
Examples of Aqueous Solutions A Cup of Coffee: Coffee + Sugar + Water Sea Water: Salt + other solutes + Water
Concentration The general term concentrationrefers to the quantity of solute in a standard quantity of solution.
Molar Concentration • Molar concentration, or molarity(M), is defined as the moles of solute dissolved in one liter (cubic decimeter) of solution.
An Example Calculation of molarity from number of moles of Solute and volume of the solution A sample of 0.0341 mol iron(III) chloride, FeCl3, was dissolved in water to give 25.0 mL of solution. What is the molarity of the solution?
An Example Calculation of mass of the solute from molarity and volume of the solution How many grams of NaCl are required to prepare 500 ml of 0.2M aqueous solution?
n = M ×V ni = M i×Vi nf = Mf×Vf Diluting Solutions Upon addition of water to a solution (dilution), the number of moles of a given substance remains constant ni = nf
An Example Preparation of dilute solutions from concentrated stock solutions For a 12M stock solution of HCl, how many ml of this solution gives 500 ml of 1.00 M solution?
Solution Stoichiometery An Example How many ml of 3.00 M HCl are required to react with 30.00 g of Zn(s)?
1 mol 2 mole 1 mol 1 mol Answer ? (mole) V 30.00 g 0.4588 moles 0.9176 moles
H2O Type of Solution Types of Solutions What happens on the microscopic level when a compound is dissolved in water? Nature of the compound Molecular Compound Ionic Compound
Ionic Compounds A model of a portion of sodium chloride crystal What Happens when sodium chloride is dissolved in water?
NaCl Na+ + Cl- Dissociation of ionic compounds in water make their solutions good conductors to electricity (electrolytes)
Methanol molecular compound dissolves in water but does not dissociate to ions (nonelectrolytes)
Acetic Acid completely dissolves but partially dissociates in water CH3COOH + H2O H3O+ + CH3COO- Weak Electrolytes Produce small number of ions in aqueous solutions