Buffer or Common Ion problems. - Kalamazoo Valley Community ...

Buffer or Common Ion problems. Identify the weak acid or base in the problem. There has to be one or the other to create a buffer. Write the ionization reaction for the weak acid or weak base. Do you recognize the common ion? It is a part of the salt. Write the equilibrium expression. If no volume are involved assigned the Initial concentrations to the two species in the equilibrium reaction that were given. What is the relationship in the Changes? What will be the relative Equilibrium concentrations.

Buffer or Common Ion problems. If Volumes are given the initial concentrations will change when the solutions are added. You must calculate the changes using M1V1 = M2V2. Test for the need to use the quadratic equation. Assign the Equilibrium concentrations in the equilibrium expression and solve for the unknown. Find the information requested in the problem. Most likely a pH value.

Addition of small amounts of acid or base to a buffer. The addition, first result in a reaction with the added substance and one of the conjugate pair in the equilibrium. If you add an acid it will react with the base of the pair. This will reduce the moles of base and increase the moles of the acid in the pair. If you add a base it will react with the acid in the pair. This will reduce the moles of acid and increase the moles of base. The volume will also change because you have added a new solution. Addition of small amounts of acid or

base to a buffer. First decide which reaction will take place. You must now determine the number of moles of each of the three key parts of this reaction. The moles of the conjugate pair for the buffer and the moles of the substance added. M = mol/L or M = mmol/mL. Make the stoichiometric adjustments to the numbers of moles. Two should decrease and one increase. The added substance should be the limiting reagent and should be completely consumed.

Now calculate the molarity of the conjugate pair from the equilibrium. Using these new concentration calculate a new pH. Titration problems A titration is first a reaction. The types of reactions we are focused on are acid-base reactions. The result of these reactions is the formation of a salt. In cases where the base has a hydroxide you will also get water. However, it is the ions of salt that can effect the pH of the solution when all the acid and base have been neutralized and the pH will vary from a neutral seven. You must also identify the ion that effects the pH. The concentration of the ion is key to calculating the pH of the solution so you will need to know the moles and volume of the ion in the ion that effects the pH. Remember the Ka or

Kb need for a salts effect on the pH must be calculated using Kw = Ka*Kb. The needed value is based on the member of the conjugate pair that appears as one of the products. Titration problems Write the reaction for the neutralization of the acid and base. Identify the ion in the salt that will effect the pH. Remember the equation is balanced in a mole to mole ratio. So you need to calculate the moles or millimoles of the acid, base and ion of interest. (M = mol/L or mmol/mL) You also need the volume of the acid, base and the resulting volume that the ion is contained in. The molarity of the ion of interest is the target of this process. Write the reaction of how the ion of

interest will effect the pH. It will either act as a proton acceptor from water of as a proton donor to water. Titration problems Write the equilibrium expression. Is this a Ka expression or a Kb expression? Remember the acid and base were completely neutralized and have a concentration of zero. Assign the Initial concentration of the ion. Relate the Change and find the relative Equilibrium concentrations. Is the given equilibrium constant the one you need or an aid to calculate the one you need. Solve for the unknown and determine the pH.

Recently Viewed Presentations

  • Holocaust Notes - Ms. Berrios' Website

    Holocaust Notes - Ms. Berrios' Website

    Jewish Ghettos: The . Nazis aimed to control the Jewish population by forcing them to live in areas that were designated for Jews only, called . ghettos. Many . ghettos were closed by barbed wire or walls and were guarded...
  • Excel 2000 xcel xcel 2000   Microsoft Office 2000.

    Excel 2000 xcel xcel 2000 Microsoft Office 2000.

    Times New Roman Wingdings Times Roman YU Times Roman SC Symbol Default Design Bitmap Image PowerPoint Presentation PowerPoint Presentation PowerPoint Presentation PowerPoint Presentation PowerPoint Presentation PowerPoint Presentation PowerPoint Presentation PowerPoint Presentation PowerPoint ...
  • Qualification Reform from 2016 GCSE Drama Specification Highlights

    Qualification Reform from 2016 GCSE Drama Specification Highlights

    mind maps . diagrams / pictures of costumes. make-up sheets. sketches of set. colour charts. mood boards. lighting cue sheets. Significant moment 1: The list is endless … any information which supports the development process. The supporting evidence must be...
  • A Q A G C SE Re lig

    A Q A G C SE Re lig

    Liturgy of the Word. On Sundays there are three readings from the Bible (the Old Testament, Paul's letters and the Gospel), a psalm and a homily. People say prayers for the Church, the world, the local community, the sick and...
  • Modern Disability

    Modern Disability

    The ADA was amended in 2008 to clarify what types of health conditions would also have anti-discrimination protection under the law. While the law never lists all health conditions that also constitute disabilities, the Amendment included a non-comprehensive list of...
  • Mandalas - Mr. Bourguignon's Online Classroom

    Mandalas - Mr. Bourguignon's Online Classroom

    Mandalas are constructed from the center outward, beginning with a dot in the center. With the placement of the center dot, the Mandalais consecrated to a partcular deity. This deity will usually be depicted in an image over the center...
  • BIOLOGY - WordPress.com

    BIOLOGY - WordPress.com

    b) the material higher on the electrostatic series gains protons from material lower on the . c) the material higher on the electrostatic series lose electrons to the material lower on the list. d) the material lower on the electrostatic...
  • Outline  Elementary Matrix  Full-rank Decomposition  Triangular Matrix Decomposition

    Outline Elementary Matrix Full-rank Decomposition Triangular Matrix Decomposition

    Elementary Matrix. Elementary Matrix. Identity matrix plus a rank-one matrix. Properties on the Elementary Matrix. Determinant. inverse matrix. for any two nonzero vectors a and b, their exists an elementary matrix such that