Unit 8 Part 4: Reactions of Acids And Bases

Reactions of Acids & Bases

Neutralization Reactions

• Neutralization Reactions occur when an acid and a base combine to form a salt and water

  • Acid + Base → Salt + Water

  • Continues until both reactants are used up

• Amounts needed can be calculated using the mole ratios in a balanced equation

  • Can also calculate the concentrations of acids and bases used

Neutralization Reaction Sample Problem 1

Salt Solutions and Salt Hydrolysis

• Salt Hydrolysis is the process by which the ions in a salt accept or donate hydrogen ions to water

  • Affected by the strength of the acid and base reacting

    • Weak acids and bases partially ionize, and are highly reversible in their reactions

    • Strong acids and bases completely ionize

Titrations

• Titration: The General addition of one solution to another to reach an equivalence point

  • It uses an acid or a base of a known concentration to determine the concentration of an unknown

  • As a strong base is added to a strong acid, the two react until they neutralize

    • Equivalence Point: the point at which a neutralization reaction is complete and the pH is equal to 7

Parts of a Titration

• Burette: a graduated glass tube with a tap at the end

• Titrand: a solution with an unknown concentration

• Titrant: a solution with a known concentration used in a titration

  • Can be either an acid or a base​

• Standard solution: a solution of known concentration

• Indicator Solution: a chemical that changes color in the presence of an acid or base

Drag and Drop

​

Placeholder

acids and bases partially ionize while ​

Placeholder

acids and bases completely ionize.

Drag these tiles and drop them in the correct blank above

Weak

Strong

Common

Uncommon

Multiple Choice

This is the solution you know the concentration of in a titration

• Titrand

• Titrant

• Indicator Solution

• Burette

Multiple Choice

When does a Neutralization Reaction end?

• When all reactants are used up

• After 3 Minutes

• When a Precipitate Forms

• Once all the reactants make contact

Multiple Choice

This is the solution you don't know the concentration of in a titration

• Titrand

• Titrant

• Indicator Solution

• Burette

Multiple Choice

This is a glass tube used to measure a titration.

• Titrand

• Titrant

• Indicator Solution

• Burette

Setting up a Titration

• Setting up Burets: Set up your buret

  • Rinse and acid buret with the titrant buret with the base three times each

  • Fill the acid buret to a point above the 0mL mark with the acid of unknown concentration

    • release some acid from the buret into the waste beaker to release air bubbles

    • Record the volume of the acid in the buret as the initial volume

  • Add three drops of the indicator solution to the flask

Setting up a Titration

• Record the initial volume of your titrant to the closest 0.01 mL

• Place your Flask with your unknown concentration under the buret so that the tip of the buret rests inside the flask

• For the first measurement: Quickly release the titrant until the equivalence point is reached

  • The equivalence point is reached when a very light color remains after 30 seconds of swirling

• Subtract the initial volume reading on the buret from the final volume to find the exact amount added​

• For every other measurement: SLOWLY release the titrant into the flask while gently swirling the Flask until the equivalence point is reached

Multiple Choice

Which of the following results shows the equivalence point in a titration

• The solution is colorless

• The Solution is a dark color

• The Solution has a light/faint Color

Multiple Choice

The first time you do a titration on a solution, at what speed should you release your titrant?

• Dripping

• Fast

• It doesn't matter

• Slow

Titration Calculations

• Once you have the volume of your solution, you can solve for the concentration of the unknown

  • Concentration would be measured Using Molarity

• Steps

  • ​Identify Balanced Chemical Equation of the reaction taking place

  • Determine the moles of your known concentration substance used

  • Convert your Moles of your known substance to Moles of your unknown substance

  • Use Your moles of unknown and amount used to determine the Molarity of the unknown

Titration Calculation Sample Problem

In a titration, 27.4 mL of 0.0154 M Ba(OH)₂ is added to a 20.0 mL sample of a HCl solution​ whose concentration is unknown until the equivalence point is reached. What is the molarity of the acid solution?

• Step 1: Identify the Balanced Equation​

Titration Calculation Sample Problem

In a titration, 27.4 mL of 0.0154 M Ba(OH)₂ is added to a 20.0 mL sample of a HCl solution​ whose concentration is unknown until the equivalence point is reached. What is the molarity of the acid solution?

• Step 1: Identify the Balanced Equation​

  • Ba(OH)₂ + 2HCl →​ BaCl₂ + 2H₂O

• Step 2: Convert the volume of your known solution into moles

  ​

Titration Calculation Sample Problem

In a titration, 27.4 mL of 0.0154 M Ba(OH)₂ is added to a 20.0 mL sample of an HCl solution​ whose concentration is unknown until the equivalence point is reached. What is the molarity of the acid solution?

• Step 1: Identify the Balanced Equation​

  • Ba(OH)₂ + 2HCl →​ BaCl₂ + 2H₂O

• Step 2: Convert the volume of your known solution into moles=4.22E-4 mol Ba(OH)₂

• Step Three: Use the mole ratio to convert from Ba(OH)​

  ​

Titration Calculation Sample Problem

In a titration, 27.4 mL of 0.0154 M Ba(OH)₂ is added to a 20.0 mL sample of a HCl solution​ whose concentration is unknown until the equivalence point is reached. What is the molarity of the acid solution?

• Step 1: Identify the Balanced Equation​

  • Ba(OH)₂ + 2HCl →​ BaCl₂ + 2H₂O

• Step 2: Convert the volume of your known solution into moles=4.22E-4 mol Ba(OH)₂

• Step 3: Use the mole ration to convert from Ba(OH)​ to HCl= 8.44E-4 mol HCl

• Step 4: Solve for your molarity​

  ​