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MOLARITY ACIDS AND BASES

MOLARITY ACIDS AND BASES. MOLARITY. What are Solute and Solvent??. Solute: The thing that is being dissolved in the solution. Solvent: The compound doing the dissolving. Identify the Solute and Solvent…. Concentration of Solute.

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MOLARITY ACIDS AND BASES

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  1. MOLARITYACIDS AND BASES

  2. MOLARITY

  3. What are Solute and Solvent?? • Solute: The thing that is being dissolved in the solution. • Solvent: The compound doing the dissolving

  4. Identify the Solute and Solvent….

  5. Concentration of Solute The amount of solute in a solution is given by its concentration. MOLARITY (M) = MOLES SOLUTE LITERS OF SOLUTION

  6. Let’s try some problems…. • See Molarity Basic Calculations

  7. How do you make a solution? • http://www.mhhe.com/physsci/chemistry/animations/chang_7e_esp/crm3s1_2.swf

  8. Making Dilutions • Diluting a solution reduces the number of moles of solute per unit of volume, but the total number of moles of solute in solution does not change.

  9. Dilutions M1V1 = M2V2 OR MiVi = MfVf M1 and V1 are for the initial solution, M2 and V2 are for the final.

  10. Question…. • How many milliliters of a solution of 4.00M KI are needed to prepare 250.0 mL of 0.760M KI?

  11. ACIDS & BASES

  12. ACIDS • Taste sour • Produce H+ (as H3O+) ions in water • Aqueous solutions of acids are electrolytes • React with certain metals to produce hydrogen gas • React with bases to form a salt and water • Turn blue litmus paper red “Blue to Red A-CID” • pH less than 7

  13. BASES • Taste bitter • Produce OH- ions in water • Aqueous solutions of bases are electrolytes • Feel slippery on the skin • React with oils and greases • React with acids to produce a salt and water • Turn red litmus paper blue “BASIC BLUE” • pH greater than 7

  14. COMMON ACIDS

  15. COMMON BASES

  16. pH = POWER OF H!! pH scale is a way of expressing the strength of acids and bases. Under 7 = acid 7 = neutralOver 7 = base

  17. pH of Common Substances

  18. Paper testing • Paper tests like litmus paper and pH paper • place a drop of the solution onto a piece of the paper • Read and record the color change. Note what the color indicates.

  19. pH indicators • Indicators are dyes that can be added that will change color in the presence of an acid or base. • Some indicators only work in a specific range of pH • Some dyes are natural, like radish skin or red cabbage

  20. PHENOLPHTHALEIN = PINK IN A BASE!

  21. UNIVERSAL INDICATOR

  22. pH meter • Tests the voltage of the electrolyte • Converts the voltage to pH • Very cheap, accurate

  23. NEUTRALIZATION REACTIONS • Excess HCl in the stomach can cause heartburn and a feeling of nausea. Antacids neutralize the stomach acid and relieve the pain of acid indigestion. You will learn what a neutralization reaction is.

  24. NEUTRALIZATION REACTIONS ACID + BASE --> SALT + WATER

  25. TITRATION Titration = • The process of adding a known amount of solution of known concentration to determine the unknown concentration of another solution End Point = • When neutralization is reached, or when the number of moles of acid and base are equal (moles = M x L) • THIS IS INDICATED WITH PHENOLPTHALEIN

  26. TITRATION Color change shows neutralization. Added base is measured with a buret. Acid solution with indicator

  27. Titration Simulation • Titration Simulation • The next class you will perform a titration in the lab. • We will NOT be going over the lab before hand and you cannot leave class until you have completed the titration correctly!!!

  28. How to Solve a Titration Problem • Write down everything you know. You will usually have the molarity and concentration of one substance, and will find the volume of the other. • Write a balanced neutralization reaction. This is when the moles of acid equal moles of base, and your indicator changes color. • Solve for the number of moles of KNOWN substance by taking the molarity and multiplying it by the volume (moles = M x L) • Using stoichiometry (mole  mole) and the balanced equation, find out the number of moles of the substance with unknown concentration. • Take the moles found in step 4 and divide by the volume used (M = moles/L).

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