William Flores-Paz Monitoring Acid-Base Titrations with a pH meter October 30, 2013 Introduction The purpose of this experiment was to record the volume of HCl and acetic acid with a NaOH with a known molarity. This data would allow us to create a graph so we could compare the two titration curves. We would then use these curves to calculate the unknown molarities. HCl + NaOH >H2O + NaCl This equation shows the relationship between the acid and the base then the reaction goes forward and they are titrated creating salt and water. This particular reaction is a strong acid and a strong base which means that when the reaction reaches the equivalence point, the moles of the acid and the base are equal and the solution is neutral so the pH should be around 7.0 depending on the final volume of each solution.
The purpose of the lab was to determine which reactant was the limiting reactant, and to see how much of the other reactant was used. The true molarity of a compound can be defined as the amount of moles per liter of that substance. The equation of this single displacement chemical reaction done during this lab is 2Al(s) + 3CuCl(aq) → 3Cu (s) + 2AlCl2 (aq). In the reaction, the solid Aluminum replaces the Copper in Copper (II) Chloride to produce solid copper, and Aluminum Chloride. In order to find which reactant is the limiting reactant, an equation based on the molarity of the Copper (II) Chloride may be used, or the products of the reaction may be observed.
Observing Changes – Materials & Procedures Materials Water Copper (II) sulphate (Powder) Copper (II) sulphate solution Iron nail Sodium carbonate Hydrochloric acid Magnesium ribbon Flame (candle) Sugar Aluminum foil Test tubes Test tube rack Tongs Medicine dropper Spoons Beakers Safety goggles Scoopulas Procedures Water and Copper (II) Sulphate Procedure 1. Add a small amount of solid copper (II) sulphate to a test tube with a scoopula. Record the physical properties. 2. Write a hypothesis on what you think will happen when water is added.
Computer Additivity of Heats of Reaction: Hess’s Law 18 (1) Solid sodium hydroxide dissolves in water to form an aqueous solution of ions. (2) Solid sodium hydroxide reacts with aqueous hydrochloric acid to form water and an aqueous solution of sodium chloride. NaOH(s) + H+(aq) ) + Cl–(aq) → H2O(l) + Na+(aq) + Cl–(aq) ∆H2 = ? OBJECTIVES • • • • In this experiment, you will Combine equations for two reactions to obtain the equation for a third reaction. Use a calorimeter to measure the temperature change in each of three reactions.
The purpose of this lab is to focus on how to make zinc iodide in a different way using compounds instead of elements, which are barium iodide and zinc sulfate. We will see if the reaction between these two compounds will occur and make a prediction by writing a chemical equation. The procedures for this lab are to place a small test tube inside a 50mL beaker and weigh it. Then, using a spatula, add 0.45±0.03 g of zinc sulfate heptahydrate into the small test tube and record the mass. After that, dissolve the sample in 2 mL of deionized water and shake the test tube for 1 to 1 ½ minutes to dissolve the solid.
Objectives: The purpose of this lab is to observe the reaction of crystal violet and sodium hydroxide by looking at the relationship between concentration and time elapsed of the crystal violet. CV+ + OH- CVOH To quantitatively observe this reaction of crystal violet, the rate law is used. The rate law tells us that the rate is equal to a rate constant (k) multiplied by the concentration of crystal violet to the power of its reaction order ([CV+]p) and the concentration of hydroxide to the power of its reaction order ([OH-]q). Rate = k[CV+]p[OH-]q To fully understand the rate law, concentrations of the substances must be looked at first. The concentration is measured in molarity.
Chapter Two: Freezing Point Depression Measurements Purpose: The purpose of this lab is to measure freezing points and freezing point depression for several solutions. The freezing point depression constant (Kf) for p-xylene was calculated from freezing point measurements and used to estimate the molar masses of three unknown solutes in a p-xylene solution. The end goal of this lab experiment is to correctly identify these three unknown solutes. The molar mass of a solute is able to be determined through freezing point depression measurements because the increase in solutes disrupts crystal formation, requiring a lower temperature to form a lattice. This colligative property is important in many industries, but is clear to see when using ordinary salt to remove ice from steps or a driveway.
For reaction (II) Pb (NO3)2 + 2KI -> PbI2+2KNO3 Lead nitrate is soluble, so it gets written as ions. The same goes for potassium iodide and potassium nitrate. Complete Ionic equation: 2 K+1 + I-1 + Pb2+ + NO32- -> PbI2 + 2K+1 + NO3-1 Net Ionic Equation: Pb+2 + 2 I-1 -> PbI2 Warm-Up Exercise 2 In this lab you will mix 25 mL of 0.05M lead nitrate with 1.4 mL of 0.025M sodium carbonate. After the reaction occurs, you will filter the solution to remove the precipitate. You will then test the remaining solution for excess lead ion and for excess carbonate ion… Imagine that you mix the two volumes and then freeze frame the reaction so the it does not proceed: 1.
Record several points of pH and NaOH added (especially near equivalence point) to be use later to prepare a titration curve. Observations and Results Part I: Solution | pH | 0.1 M HCl | .70 | 0.1 M NaOH | 13.30 | Part II: Volume of 0.1 M NaOH at equivalence point: 35mL pH at equivalence point: 11.45 Molarity of the Unknown Acid A (HCl): 2.0 x 10-4 Discussion In this lab, we found out that water self ionizes itself into hydrogen ion and hydroxide ion naturally to a very small extent. An indicator, in an acid base reaction, is a substance whose color changes over a particular pH range. Phenolphthalein is an example of an indicator which changes from colorless to pink as pH goes from 8 to 10. We plotted the pH against the amount of base added producing a
Observations of Physical and Chemical Changes Purpose- The different tests can interact and change in different ways, by doing these tests we can figure out if it could be either a physical change or chemical change by observing the test and chemicals. Procedure- In test one, you mixed a small amount of iodine in each test tube and fill one of the with just tap water and the second one with hexane. Test two, you measure 5 grams of barium hydroxide and same measurement of ammonium chloride and stir with a stirring rod. Test three, you use a small piece of steel wool and you place it over a Bunsen burner using tongs and observe what you see. Test four, by using a plastic bag, you place a spoon full of calcium chloride in one corner and