Titrations!

Titrations Titration: adding a known amount of solution of known concentration to a solution with an unknown concentration Goal: To determine the unknown concentration of a solution

Titrations Endpoint: the point of neutralization in a titration How do we know we reached the endpoint in a titration? We use an indicator and look for a color change! http://www.youtube.com/watch?v=g8jdCWC10vQ

Titration Example A 2.5 L solution of H2SO4 is completely neutralized by 0.5 L of 1.0 M NaOH. What is the concentration of the H2SO4 solution? 1.0 M NaOH Show your work for each step: 1. Write the balanced neutralization reaction 2. Start with the volume of the known 3. Find the moles of your known using the volume and concentration 4. Use the molar ratio (the coefficients) to determine the unknown number of moles ? M H2SO4 5. Divide the moles by the volume to get concentration OR convert to grams

Titration Example A 2.5 L solution of H2SO4 is completely neutralized by 0.5 L of 1.0 M NaOH. What is the concentration of the H2SO4 solution? 1. Write the balanced neutralization reaction H2SO4 + 2 NaOH  Na2SO4 + 2 H2O 2. Start with your known volume 0.5 L of 1.0 M NaOH 3. Find the moles of your known using the volume and concentration 0.5 L NaOH x 1 mol NaOH 1 L NaOH = 0.50 mol NaOH

Titration Example continued A 2.5 L solution of H2SO4 is completely neutralized by 0.5 L of 1.0 M NaOH. What is the concentration of the H2SO4 solution? H2SO4 + 2 NaOH  Na2SO4 + 2 H2O 4. Use the molar ratio (the coefficients) to determine the unknown number of moles 0.50 mol NaOH x 1 mol H2SO4 2 mol NaOH = 0.25 mol H2SO4 5. Divide the moles by the volume to get concentration 0.25 mol H2SO4 2.5 L H2SO4 = 0.1 M H2SO4

Titration Practice A 1.5 L solution of HCl is completely neutralized by 2.0 L of 0.5 M Al(OH)3. What is the concentration of the HCl solution? 0.5 M Al(OH)3 Show your work for each step: 1. Write the balanced neutralization reaction 2. Start with your known volume or mass 3. Find the moles of your known using the volume and concentration 4. Use the molar ratio (the coefficients) to determine the unknown number of moles ? M HCl 5. Divide the moles by the volume to get concentration OR convert to grams

Example #2 A 25 mL solution of H2SO4 is completely neutralized by 6.5 mL of 1.0 M NaOH. What is the concentration of the H2SO4 solution? 1. Write the balanced neutralization reaction H2SO4 + 2 NaOH  Na2SO4 + 2 H2O 2. Start with your known value 0.0065 L of 1.0 M NaOH 3. Find the moles of your known using the volume and concentration 0.0065 L NaOH x 1 mol NaOH 1 L NaOH = 0.0065 mol NaOH

Titration Example continued A 25 mL solution of H2SO4 is completely neutralized by 6.5 mL of 1.0 M NaOH. What is the concentration of the H2SO4 solution? H2SO4 + 2 NaOH  Na2SO4 + 2 H2O 4. Use the molar ratio (the coefficients) to determine the unknown number of moles 0.0065 mol NaOH x 1 mol H2SO4 2 mol NaOH = 0.00325 mol H2SO4 5. Divide the moles by the volume to get concentration 0.00325 mol H2SO4 0.025 L H2SO4 = 0.13 M H2SO4