Acid-Base Properties of Salt Solutions
What are Salt Solutions?
Simply put, salts are solids that contain cations and anions arranged in a crystalline lattice. When they dissolve in water, the dissociate into individual ions that become hydrated. They may or may not affect the pH of the solution depending on the nature of the ions.
Simply put, salts are solids that contain cations and anions arranged in a crystalline lattice. When they dissolve in water, the dissociate into individual ions that become hydrated. They may or may not affect the pH of the solution depending on the nature of the ions.
LESSON OVERVIEW (SPECIFIC EXPECTATIONS E1.2, E2.4, E3.6)
Lesson Hook:
Stalactites and Stalagmites are a consequence of the acidic properties of the non-metal oxide calcium carbonate, CaCO3(s) dissolving in water. To introduce the concept of salt solutions and the role they play in chemical equilibrium and in nature, create your own stalactites and stalagmites using a two beakers, some sodium carbonate and a towel. Click below for a video demonstrating the ease of this magnificent demonstration courtesy of YouTube. Please note that this is a multi day demonstration, as it will take some time for a substantial amount to form.
Stalactites and Stalagmites are a consequence of the acidic properties of the non-metal oxide calcium carbonate, CaCO3(s) dissolving in water. To introduce the concept of salt solutions and the role they play in chemical equilibrium and in nature, create your own stalactites and stalagmites using a two beakers, some sodium carbonate and a towel. Click below for a video demonstrating the ease of this magnificent demonstration courtesy of YouTube. Please note that this is a multi day demonstration, as it will take some time for a substantial amount to form.
Action:
Once reviewing the definition of a Bronsted-Lowry acid and base and giving a brief lecture on the properties of salt solutions, have students determine the effect on pH of a variety of salt solutions using the mini-lab given below as a guide. Students can measure the initial and final pH of salt solutions and then determine the chemical equations and ion concentrations of each. You can also have students work in the other direction by having them first identify the reaction taking place, calculate the theroritical pH based on that reaction and then confirm their results by measuring the pH. Click below to download a copy of this mini-lab courtesy of .docstoc
Once reviewing the definition of a Bronsted-Lowry acid and base and giving a brief lecture on the properties of salt solutions, have students determine the effect on pH of a variety of salt solutions using the mini-lab given below as a guide. Students can measure the initial and final pH of salt solutions and then determine the chemical equations and ion concentrations of each. You can also have students work in the other direction by having them first identify the reaction taking place, calculate the theroritical pH based on that reaction and then confirm their results by measuring the pH. Click below to download a copy of this mini-lab courtesy of .docstoc
hydrolysis_and_ph_of_salt_solutions.doc | |
File Size: | 42 kb |
File Type: | doc |
Misconceptions Addressed: Students commonly believe substances containing H+ are acidic and substances containing OH- are basic.
Debrief:
Have students work in groups to come up with the equations that govern the demonstration given above while providing guidance as necessary. Have students check their answers with a seatmate (think-pair-share) and then come up with a class consensus as to the reactions taking place in the beakers and on the towel.
FOPP: Commitment to students and student learning, professional knowledge and professional practice.
Debrief:
Have students work in groups to come up with the equations that govern the demonstration given above while providing guidance as necessary. Have students check their answers with a seatmate (think-pair-share) and then come up with a class consensus as to the reactions taking place in the beakers and on the towel.
FOPP: Commitment to students and student learning, professional knowledge and professional practice.
The concept of Salt Solutions can be reinforced in a variety of ways to appeal to all forms of multiple intellegences. Click below for a few resources that can be used in conjunction with a lesson to further demonstrate the concept of Salt Solutions.