Acids and Metals Acids react with certain metals to produce hydrogen gas and the metal salt. metal acid metal salt hydrogen gas Magnesium reacts rapidly with acid and forms a salt of magnesium and H2 gas.

Acids and Carbonates Acids react with carbonates or bicarbonates (hydrogen carbonate), to produce carbon dioxide gas, water, and an ionic compound (salt). The acid reacts with CO32− to produce carbonic acid, H2CO3, which breaks down rapidly to CO2 and H2O. metal acid carbon dioxide metal salt water

Acid Rain Acid rain is a term given to precipitation, such as rain, snow, hail, or fog, that has a pH of 5.6 or less. is formed when sulfur impurities from coal and oil react with water and oxygen gas to form H2SO4. degrades marble statues and limestone structures. interferes with photosynthesis, killing plants and trees.

Acid Rain A marble statue in Washington Square Park has been eroded by acid rain. Acid rain has severely damaged forests in Eastern Europe.

Learning Check Write the products and the balanced chemical equation for each of the following reactions of acids.

Solution Write the products and the balanced chemical equation for each of the following reactions of acids.

Neutralization Reactions Neutralization is the reaction of an acid, such as HCl and a base, such as NaOH. acid base salt water The net ionic equation shows that H+ combines with OH− to form H2O, leaving the ions Na+ and Cl- in solution Crossing out spectator ions we get

Guide to Balancing an Equation for Neutralization

Balancing Neutralization Reactions Write the balanced equation for the neutralization of magnesium hydroxide and nitric acid. Step 1 Write the reactants and products. Step 2 Balance the H in the acid with the OH in the base.

Balancing Neutralization Reactions Write the balanced equation for the neutralization of magnesium hydroxide and nitric acid. Step 3 Balance the H2O with the H and OH. Step 4 Write the salt from the remaining ions.

Learning Check Write the balanced equation for the reaction of the base KOH with the strong acid, H2SO4.

Solution Write the balanced equation for the reaction of the base KOH with the strong acid, H2SO4. Step 1 Write the reactants and products. Step 2 Balance the H in the acid with the OH in the base.

Solution Write the balanced equation for the reaction of the base KOH with the strong acid, H2SO4. Step 3 Balance the H2O with the H and OH. Step 4 Write the salt from the remaining ions.

Learning Check Select the correct group of coefficients for the following neutralization equations. 1. A. 1, 3, 3, 1 B. 3, 1, 1, 1 C. 3, 1, 1, 3 2. A. 3, 2, 2, 2 B. 3, 2, 1, 6 C. 2, 3, 1, 6

Solution Select the correct group of coefficients for the following neutralization equations. 1. Answer is C. 3, 1, 1, 3. 2. Answer is B. 3, 2, 1, 6.

Acid–Base Titration Titration is a laboratory procedure often used to determine the molarity of an acid. uses a base, such as NaOH, to neutralize a measured volume of an acid. Base (NaOH) Acid solution

Indicator An indicator is added to the acid in the flask. causes the solution to change color when the acid is neutralized.

End Point of Titration At the end point, moles of OH− equal moles of H3O+ in the acid, and the indicator has a faint, permanent pink color.

Concentration of the Acid From the measured volume of the NaOH solution at the end point and its molarity, we calculate the number of moles of NaOH used, the moles of acid in the flask, and the concentration of the acid.

Guide to Calculations for an Acid–Base Titration

Calculating Molarity from a Titration with a Base What is the molarity of an HCl solution if 18.5 mL of a 0.225 M NaOH are required to neutralize 10.0 mL HCl? Analyze the Problem.

Calculating Molarity from a Titration with a Base What is the molarity of an HCl solution if 18.5 mL of a 0.225 M NaOH are required to neutralize 10.0 mL HCl? Step 1 Write the balanced equation for the neutralization. Step 2 Write a plan to calculate molarity or volume. liters molarity moles mole–mole moles divide molarity of NaOH NaOH NaOH factor HCl by liters

Calculating Molarity from a Titration with a Base What is the molarity of an HCl solution if 18.5 mL of a 0.225 M NaOH are required to neutralize 10.0 mL HCl? Step 3 State equalities and conversion factors. 1 L NaOH and 0.225 mole NaOH 0.225 mole NaOH 1 L NaOH 1 mole of NaOH = 1 mole of HCl 1 mole NaOH and 1 mole HCl 1 mole HCl 1 mole NaOH

Calculating Molarity from a Titration with a Base What is the molarity of an HCl solution if 18.5 mL of a 0.225 M NaOH are required to neutralize 10.0 mL HCl? Step 4 Set up the problem to calculate the needed quantity. 0.0185 L NaOH x 0.225 mole NaOH x 1 mole HCl 1 L NaOH 1 mole NaOH = 0.00416 mole HCl = 0.416 M HCl 0.0100 L HCl

Learning Check Calculate the volume in liters of 2.00 M H2SO4 required to neutralize 50.0 mL (0.0500 L) of 1.00 M KOH. A. 0.0125 L B. 0.0500 L C. 0.0200 L

Solution Calculate the volume in liters of 2.00 M H2SO4 required to neutralize 50.0 mL (0.0500 L) of 1.00 M KOH. H2SO4(aq) + 2KOH(aq) K2SO4(aq) + 2H2O(l) Step 1 Write the balanced equation for the neutralization. Step 2 Write a plan to calculate molarity or volume. liters molarity moles mole–mole moles molarity liters of KOH KOH KOH factor H2SO4 H2SO4 H2SO4

Solution Calculate the volume in liters of 2.00 M H2SO4 required to neutralize 50.0 mL (0.0500 L) of 1.00 M KOH. Step 3 State equalities and conversion factors. 1 L KOH and 1.00 mole KOH 1.00 mole KOH 1 L KOH 2 moles of KOH = 1 mole of H2SO4 2 moles KOH and 1 mole H2SO4 1 mole H2SO4 2 moles KOH

Solution Calculate the volume in liters of 2.00 M H2SO4 required to neutralize 50.0 mL (0.0500 L) of 1.00 M KOH. Step 3 State equalities and conversion factors. 1 L of H2SO4 = 2.00 moles of H2SO4 1 L H2SO4 and 2.00 moles H2SO4 2.00 moles H2SO4 1 L H2SO4

Solution Calculate the volume in liters of 2.00 M H2SO4 required to neutralize 50.0 mL (0.0500 L) of 1.00 M KOH. Step 4 Set up the problem to calculate the needed quantity. 0.0500 L KOH x 1.00 mole KOH x 1 mole H2SO4 1 L KOH 2 moles KOH x 1 L H2SO4 = 0.0125 L H2SO4 2.00 moles H2SO4 Answer is A.