Acid Base Titration

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Acid Base Titration Purpose: The purpose is to calculate the molarity of a NaOH solution by titrating the base with 5mL of standard HCl solution in each trial. By adding the base with unknown molarity to the acid with 0.10M the molarity of NaOH can be calculated. The base, NaOH, helps bring the pH of the acid, HCl, closer to seven, which neutralizes it. When using the buret the amount of NaOH used is able to be determined. Then by writing a balanced chemical equation and using the titration formula, Nb+Ma+Va=Na+MbVb , the molarity is able to be determined. Procedure: 1) Using the graduated cylinder add 10.0 mL of water into the Erlenmeyer flask. 2) Add 5.0 mL of HCl into the flask using another graduated cylinder because acid goes into water when mixing them. 3) Add three drops of phenolphthalein indicator into the flask. 4) Swirl the flask in circular movements to mix the substances. 5) Put the flask under the buret of NaOH solution, make sure the buret’s tip is inside the flask’s opening 6) Observe and record the initial volume of the NaOH buret. Note the markings on the buret. 7) Begin the titration by twisting the lever on the side of the buret until small drops come out. Keep swirling the solution until a pink color is visible throughout from the phenolphthalein. 8) If over titration occurs ask the teacher for further instruction. 9) Write down the final volume in the NaOH buret 10) Subtract the final volume of NaOH from the initial volume. 11) Repeat this process at least twice more. Materials: * Buret (50mL) * Graduated Cylinder (10mL) * Beakers (250mL) * Buret stand * Erlenmeyer flask (125mL) * Safety goggles * Buret clamp * 0.10M HCl (aq) (25.0mL) * NaOH (aq) Vocab: * Standard Solution: a solution containing a precisely known concentration *
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