This does not happen because most of the reactions in

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: s and Bases Salt Prediction: acidic, basic or neutral? General Chemistry I and II Lab Manual pH Acidic, basic or neutral? Strongly or weakly? Observations: Dakota State University page 1 42 of 232 Experiment 11: Acids and Bases General Chemistry I and II Lab Manual Pre-lab Questions: 1. We are making a serial dilution of HCl and NaOH; what does this mean? 2. How do you suppose we will decide if a solution is “strongly” or “weakly” acidic or basic? Dakota State University page 1 43 of 232 Experiment 11: Acids and Bases General Chemistry I and II Lab Manual Post-lab Questions: 1. What was the biggest surprise to you in the household items? 2. Some salts you could predict the pH of in solution, some you could not. Why? Dakota State University page 1 44 of 232 Experiment 12: Le Chatliere’s Principle General Chemistry I and II Lab Manual Experiment 12: Le Chatliere’s principle Purpose: To gain experience with Le Chatliere’s principle Purloin: To steal Background: See “Using the Pasco System” and “Basic Laboratory Procedures”; Pipettes Introduction: Equilibia are critical to life. I mean, if chemical reactions were not reversible, we would be one-shot machines. Our metabolism, which is nothing more than the series of chemical reactions that keep us alive, would run through their cycle one time, and we would expire. This does not happen, because most of the reactions in our metabolic pathways are reversible; what is used up in one step, is regenerated in the next. Le Chatliere tells us that, when it comes to equilibria, we are allowed to be bullies. We can push the equilibrium to the reactants by adding products, or to the products by adding reactants. We can even push the equilibrium around by changing the conditions, such as temperature. Today, we will be playing with what is probably one of the most important equilibria to us as humans; acid/base equilibria. Essentially, we are going to create a buffer solution, and play with it for a bit. We’ll be using an (unknown) organic acid; the general equilibria will be HA (aq) ß à H+ (aq) + A- (aq) We are using an organic acid because they are all weak, and therefore appropriate choices for creating a buffer solution. Recall the equilibrium constant, and equilibria calculations as you’ve learned them in class, and we will see, I hope, some of these principles come to life. Procedure: You will need to start the Pasco system with the pH probe. Use the standard methods for starting the system; you will want to choose manual data collection. Part I: Determination of the equilibrium constant Ka You will find two bottles in the lab, one of an unknown organic acid, and one of its corresponding salt. Both of these are the same concentration which will be provided for you in class. Using the pipettes provided, thoroughly mix 20.00 mL of each of these solutions into a Dakota State University page 1 45 of 232 Experiment 12: Le Chatliere’s Principle General Chemistry I and II Lab Manual clean, dry flask. Determine the pH of...
View Full Document

Ask a homework question - tutors are online