Reactions in Aqueous Solutions

Aqueous Solutions aqueous solutions -solute dissolved in water nonelectrolytes - aqueous solutions do not conduct electricity C 2 H 5 OH - ethanol

Aqueous Solutions C 6 H 12 O 6 - glucose (blood sugar)

Aqueous Solutions C 12 H 22 O 11 - sucrose (table sugar)

Molecular compounds in water (e.g., CH 3 OH): no ions are formed. If there are no ions in solution, there is nothing to transport electric charge. Properties of Aqueous Solution

Ionic Compounds in Water Ions dissociate in water. In solution, each ion is surrounded by water molecules. Transport of ions through solution causes flow of current. Properties of Aqueous Solution

Strong electrolytes: completely dissociate in solution. For example: Weak electrolytes: produce a small concentration of ions when they dissolve. These ions exist in equilibrium with the unionized substance. For example: Properties of Aqueous Solution

strong electrolytes - extremely good conductors of electricity HCl, HNO 3, etc. strong soluble acids strong soluble acids NaOH, KOH, etc. strong soluble bases NaCl, KBr, etc. soluble ionic salts ionize in water essentially 100%

Properties of Aqueous Solution weak electrolytes CH 3 COOH, (COOH) 2 weak acids NH 3, Fe(OH) 3 weak bases some soluble covalent salts ionize in water much less than 100%

Strong and Weak Acids acids generate H + in aqueous solutions strong acids ionize 100% in water

Strong and Weak Acids acids generate H + in aqueous solutions strong acids ionize 100% in water

Strong and Weak Acids entire list of strong water soluble acids HCl - hydrochloric acid HBr - hydrobromic acid HI - hydroiodic acid HNO 3 - nitric acid H 2 SO 4 - sulfuric acid HClO 3 - chloric acid HClO 4 - perchloric acid

Strong and Weak Acids weak acids ionize less than 100% in water 10% or less! some common weak acids HF - hydrofluoric acid CH 3 COOH - acetic acid (vinegar) H 2 CO 3 - carbonic acid (soda water) H 2 SO 3 - sulfurous acid HNO 2 - nitrous acid H 3 PO 4 - phosphoric acid

Strong and Weak Acids weak acids ionize as reversible or equilibrium reactions CH 3 COOH acetic acid why they ionize less than 100%

Strong Soluble Bases bases produce OH - ions in solution strong soluble bases ionize 100% in water

Strong Soluble Bases entire list of strong soluble bases LiOH - lithium hydroxide NaOH - sodium hydroxide KOH - potassium hydroxide RbOH - rubidium hydroxide CsOH - cesium hydroxide Ca(OH) 2 - calcium hydroxide Sr (OH) 2 - strontium hydroxide Ba (OH) 2 - barium hydroxide

Insoluble Bases ionic but insoluble in water not very basic Cu(OH) 2 - copper (II) hydroxide Fe(OH) 2 - iron (II) hydroxide Fe(OH) 3 - iron (III) hydroxide Zn(OH) 2 - zinc (II) hydroxide Mg(OH) 2 - magnesium hydroxide

Weak Bases covalent compounds that ionize slightly in water NH 3 - ammonia is most common

Solubility Rules strong acids completely water soluble strong bases completely water soluble soluble ionic salts Solubility Rules found on my website or in the book

Dissociation = pre-formed ions in solid move apart in solution. Ionization = neutral substance forms ions in solution. Acid = substances that ionizes to form H + in solution (e.g. HCl, HNO 3, CH 3 CO 2 H, lemon, lime, vitamin C). Bases = substances that react with the H + ions formed by acids (e.g. NH 3, Drano™, Milk of Magnesia™). Acids, Bases, and Salts

Reactions in Aqueous Solutions molecular equations all reactants & products in molecular or ionic form total ionic equation ions as they exist in solution

Reactions in Aqueous Solutions net ionic equation shows ions that participate in reaction and removes spectator ions spectator ions do not participate in the reaction

Exchange or Metathesis reactions involve swapping ions in solution: AX + BY  AY + BX. Exchange reactions will lead to a change in solution if one of three things occurs: an insoluble solid is formed (precipitate), weak or nonelectrolytes are formed, or an insoluble gas is formed. Displacement Reactions

Precipitation Reactions form an insoluble compound crystals molecular equation

Precipitation Reactions form an insoluble compound crystals molecular equation total ionic reaction

Precipitation Reactions total ionic reaction

Precipitation Reactions total ionic reaction net ionic reaction

Precipitation Reactions net ionic reaction

Neutralization occurs when a solution of an acid and a base are mixed: HCl(aq) + NaOH(aq)  H 2 O(l) + NaCl(aq) Notice we form a salt (NaCl) and water. Salt = ionic compound whose cation comes from a base and anion from an acid. Neutralization between acid and metal hydroxide produces water and a salt. Acids, Bases, and Salts

Acid-Base Reactions acid + base salt + water recall the acids and bases from before molecular equation

Acid-Base Reactions acid + base salt + water recall the acids and bases from before molecular equation total ionic equation

Acid-Base Reactions total ionic equation net ionic equation

Acid-Base Reactions net ionic equation

Acid-Base Reactions molecular equation

Acid-Base Reactions molecular equation total ionic equation

Acid-Base Reactions total ionic equation net ionic equation

Acid-Base Reactions net ionic equation

Solution = solute dissolved in solvent. Solute: present in smallest amount. Solute: present in smallest amount. Water as solvent = aqueous solutions. Water as solvent = aqueous solutions. Change concentration by using different amounts of solute and solvent. Change concentration by using different amounts of solute and solvent. Molarity: Moles of solute per liter of solution. If we know: molarity and liters of solution, we can calculate moles (and mass) of solute. If we know: molarity and liters of solution, we can calculate moles (and mass) of solute. Solution Composition

Molarity: Moles of solute per liter of solution. Solution Composition

Concentration of Solutions solution - one substance dissolved in another, commonly one is a liquid solution - one substance dissolved in another, commonly one is a liquid concentration - amount of solute dissolved in a solvent concentration - amount of solute dissolved in a solvent “sweet tea”“sweet tea” mixed drinksmixed drinks units of concentration units of concentration

Molarity (Molar Concentration) molarity = mol solute/L of solution = M molarity = mol solute/L of solution = M Calculate the molarity of a solution that contains 12.5 g of sulfuric acid in 1.75 L of solution. Calculate the molarity of a solution that contains 12.5 g of sulfuric acid in 1.75 L of solution.

Molarity (Molar Concentration) molarity = mol solute/L of solution = M molarity = mol solute/L of solution = M Calculate the molarity of a solution that contains 12.5 g of sulfuric acid in 1.75 L of solution. Calculate the molarity of a solution that contains 12.5 g of sulfuric acid in 1.75 L of solution.

Molarity (Molar Concentration) Determine the mass of calcium nitrate required to prepare 3.50 L of M Ca(NO 3 ) 2. Determine the mass of calcium nitrate required to prepare 3.50 L of M Ca(NO 3 ) 2.

Molarity (Molar Concentration) Determine the mass of calcium nitrate required to prepare 3.50 L of M Ca(NO 3 ) 2. Determine the mass of calcium nitrate required to prepare 3.50 L of M Ca(NO 3 ) 2.

Dilution of Solutions take a concentrated solution and add water to it take a concentrated solution and add water to it make tea “less sweet”make tea “less sweet” number of moles of solute remains constant number of moles of solute remains constant M 1 V 1 = M 2 V 2 works because # of moles is constant M 1 V 1 = M 2 V 2 works because # of moles is constant If 10 mL of 12 M HCl is added to enough water to give 100 mL of solution, what is concentration of solution? If 10 mL of 12 M HCl is added to enough water to give 100 mL of solution, what is concentration of solution?

Dilution of Solutions take a concentrated solution and add water to it take a concentrated solution and add water to it make tea “less sweet”make tea “less sweet” number of moles of solute remains constant number of moles of solute remains constant M 1 V 1 = M 2 V 2 works because # of moles is constant M 1 V 1 = M 2 V 2 works because # of moles is constant If 10 mL of 12 M HCl is added to enough water to give 100 mL of solution, what is concentration of solution? If 10 mL of 12 M HCl is added to enough water to give 100 mL of solution, what is concentration of solution? (10 mL)(12 M) = M 2 (100 mL) M 2 = 1.2 M HCl

Dilution of Solutions What volume of 18.0 M sulfuric acid is required to make 2.50 L of a 2.40 M sulfuric acid solution? What volume of 18.0 M sulfuric acid is required to make 2.50 L of a 2.40 M sulfuric acid solution?

Dilution of Solutions What volume of 18.0 M sulfuric acid is required to make 2.50 L of a 2.40 M sulfuric acid solution? What volume of 18.0 M sulfuric acid is required to make 2.50 L of a 2.40 M sulfuric acid solution?

Stoichiometry with Solutions There are two different types of units: laboratory units (macroscopic units: measure in lab); chemical units (microscopic units: relate to moles). Always convert the laboratory units into chemical units first. Grams are converted to moles using molar mass. Volume or molarity are converted into moles using M = mol/L. Use the stoichiometric coefficients to move between reactants and product.

Stoichiometry with Solutions

What volume of M BaCl 2 is required to completely react with 4.32 g of Na 2 SO 4 ? What volume of M BaCl 2 is required to completely react with 4.32 g of Na 2 SO 4 ?

Stoichiometry with Solutions What volume of M NaOH will react with 50.0 mL 0f M aluminum nitrate? What mass of aluminum hydroxide precipitates? What volume of M NaOH will react with 50.0 mL 0f M aluminum nitrate? What mass of aluminum hydroxide precipitates? Al(NO 3 ) NaOH  Al(OH) NaNO 3

Stoichiometry with Solutions What volume of M NaOH will react with 50.0 mL 0f M aluminum nitrate? What mass of aluminum hydroxide precipitates? What volume of M NaOH will react with 50.0 mL 0f M aluminum nitrate? What mass of aluminum hydroxide precipitates? Al(NO 3 ) NaOH  Al(OH) NaNO 3

Stoichiometry in Solution What mass of Al(OH) 3 precipitates in (a)? What mass of Al(OH) 3 precipitates in (a)?

Stoichiometry in Solution What mass of Al(OH) 3 precipitates in (a)? What mass of Al(OH) 3 precipitates in (a)?

Titrations

Suppose we know the molarity of a NaOH solution and we want to find the molarity of an HCl solution. We know: molarity of NaOH, volume of HCl. What do we want? Molarity of HCl. What do we do? Take a known volume of the HCl solution, measure the mL of NaOH required to react completely with the HCl.

Titrations What do we get? Volume of NaOH. We know molarity of the NaOH, we can calculate moles of NaOH. Next step? We also know HCl + NaOH  NaCl + H 2 O. Therefore, we know moles of HCl. Can we finish? Knowing mol(HCl) and volume of HCl (20.0 mL above), we can calculate the molarity.

Titrations What is the molarity of a KOH solution if 38.7 mL of KOH solution is required to react with 43.2 mL of M HCl? What is the molarity of a KOH solution if 38.7 mL of KOH solution is required to react with 43.2 mL of M HCl?

Titrations What is the molarity of a barium hydroxide solution if 44.1 mL of M HCl is required to react with 38.3 mL of the Ba(OH) 2 solution? What is the molarity of a barium hydroxide solution if 44.1 mL of M HCl is required to react with 38.3 mL of the Ba(OH) 2 solution?

Titrations What is the molarity of a barium hydroxide solution if 44.1 mL of M HCl is required to react with 38.3 mL of the Ba(OH) 2 solution? What is the molarity of a barium hydroxide solution if 44.1 mL of M HCl is required to react with 38.3 mL of the Ba(OH) 2 solution?

Titrations What is the molarity of a barium hydroxide solution if 44.1 mL of M HCl is required to react with 38.3 mL of the Ba(OH) 2 solution? What is the molarity of a barium hydroxide solution if 44.1 mL of M HCl is required to react with 38.3 mL of the Ba(OH) 2 solution?

Synthesis Question Nylon is made by the reaction of hexamethylene diammine Nylon is made by the reaction of hexamethylene diammine with adipic acid

Synthesis Question in a 1 to 1 mole ratio. The structure of nylon is: in a 1 to 1 mole ratio. The structure of nylon is: where the value of n is typically 450,000. On a daily basis, a DuPont factory makes 1.5 million pounds of nylon. How many pounds of hexamethylene diamine and adipic acid must they have available in the plant each day?

Group Activity Manganese dioxide, potassium hydroxide and oxygen react in the following fashion: Manganese dioxide, potassium hydroxide and oxygen react in the following fashion: A mixture of g of MnO 2, 26.6 L of M KOH, and g of O 2 is allowed to react as shown above. After the reaction is finished, g of K 2 MnO 4 is separated from the reaction mixture. What is the per cent yield of this reaction?