chem lab 20 - Sheldon Pope & Brandon Pezzuto Chem 404...

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Chem 404 section 7 4-17-08 Weak Acid Titration Experiment 1: 1. Bromocresol green is a good choice of indicator because it indicates acid, base or neutral solution. When a solution with a pK a of less than 5.0 is exposed to bromocresol green, it creates yellow spots on a dark background. Yellow indicates and acid, Blue indicates a base or neutral solution. 2. NaHCO 3 + H 2 O OH - + NaCO 2 NaNO 2 Na + + NO 2 - Na 2 SO 4 Na + + SO 4 2- Experiment 2: 3. The reason that NO does not dissociate easily in water because preferably, NO likes to be in the gaseous state. NO gas is the way the compound is present naturally in the environment. This is because the K value for NO is small therefore it is very insoluble in water. 4. NO x enter the water droplets because naturally NO is attracted to water. This attraction occurs because of the arrangement of the molecules between the two molecules and in order to create NO 2 there must be a union between NO x and H 2 0. 5. The gas reacts with the substances by the inside out. The drops in the inner most portion of the Petri dish changed color first and as time passed the drops with the larger perimeter changed to follow. Due to the fact that the concentration was greatest toward the middle those drops changed color first and then the concentration was distributed to the remainder of the Petri dish that was created to resemble the atmosphere. 6. The size to the drop that was put on the Petri dish does have an effect on the amount of absorbency they system may have. The larger the surface area the larger the expected amount of absorbency will be. Volume also has a major factor in the absorbency. The larger the volume the more absorbance and dissolving in the solutes. 7.
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chem lab 20 - Sheldon Pope & Brandon Pezzuto Chem 404...

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