Limiting Concentration Lab Report

The purpose of the lab is to acquire the percent composition of zinc and copper. The procedure included obtaining a post 1983 penny and washing it with soap and water. Using a triangular file, we made an X on the penny. Then, we cleaned the top and bottom of the penny with steel wool until it was shiny. We rinsed the penny in acetone and dried it with paper towel.

Marwah Alabbad Post lab 10/21/15 Question 1: 1. Experiment 1: Number of trails NaOH concentration (M) Volume of HCl solution (mL) Initial volume of NaOH(mL) final volume of NaOH(mL) The volume of NaOH to titrate HCl (mL) Concentration of HCl (M) 1st 0.1023 25.0 10.05 36.12 26.07 0.085 2nd 0.1023 25.0 5.74 31.40 25.66 0.105 3rd 0.1023 25.0 9.84 35.52 25.68 0.105 First trail calculation: 0.02607L× (0.1023mole NaOH/1L)×(1 mol of HCL/1 mol of NaOH)×(1/0.025)= 0.085M of HCl

I have chosen to use this scale of strontium nitrate because it will give me more results so the graph will be more accurate. I will measure the precipitate formed with a ruler in millimetres. I have decided to measure this in millimetres because it is a more accurate measurement so I will be able to compare them easily and more precisely. 1. Place 8 boiling tubes in a boiling tube rack and label them 1-8.

each paper remained it's original color, thus concluding that the unknown was neutral. These results also led the students to believe the unknown was CaCl2 since it was listed in the neutral column. After the litmus test was conducted the students added a few drops of Na3PO4 to the unknown. When these two were combined a precipitate was formed. This final test on unknown F verified that it was CaCl2.

In order to find the amount of a product made during a double displacement reaction, the product has to be separated from the solution. From this number of moles of precipitate can be calculated. From there the number of moles of reactants can be calculated using the mole ratios of the particular reaction that occurred. As seen in Table 5 it is shown that by finding out the number of moles of the unknown, the molar mass of the unknown can be calculated. From the found mass of the unknown compound, the mound of the original ion can be found.

The last goal was to determine the percent yield of a product formed during a reaction with the unknown compound. Experimental Design The first day of lab consisted of various preliminary tests that helped identify the unknown compound.

To calculate the experimental mass the substance of each bag and the bag its self was measured using a balance. After gathering the mass subtract the mass of the empty bag to the mass of the unknown substance, in order to just have the mass of the substance. Afterward the mass of the unknown substance was divided by the number of moles recorded on the bag of the substance. The measurements are displayed on the table

Using the equation m = ΔTf/Kf , the molality of the unknown solution was found. Then, moles of unknown were calculated, which was used to calculate the average molar mass of unknown. Theory: After the experiment was completed, the data

I. Purpose: To experimentally determine the mass and the mole content of a measured sample. II. Materials: The materials used in this experiment a 50-mL beaker, 12 samples, a balance and paper towels. III.

Testing for the Presence of Macromolecules in McDonald’s Happy Meals Clayton Wagoner MST Biology White 4 duPont Manual High School Introduction Carbohydrates, lipids, proteins, and nucleic acids are organic molecules found in every living organism. These macromolecules are large carbon based structures. The macromolecules are assembled by joining several smaller units, called monomers, together through a chemical reaction called dehydration synthesis. The resulting polymer can be disassembled through the complementary process called hydrolysis.

To determine the rate of reaction there are many method to be used for example, measuring the mass after the product has been added and measuring the difference in mass on the duration of a digital scale. Another method, which will be used in this experiment is using a gas syringe to measure the volume of the gas which has been produced. The cylinder inside, will be pushed out to show a quantitative presentation of the volume produced by the reaction. Hypothesis

Using the Law of Definite Proportions, the mass of this product was used to determine the number of moles of copper and chlorine in the sample, which led to being able to determine the

(0.01 moles of NaOH) x (1 mole Ca(OH)2/ 2 moles of NaOH) = 0.005 moles of Ca(OH)2 Tube 1: (0.0020 moles of CaCl2) x (1 mole Ca(OH)2/ 1 mole of CaCl2) = 0.002 moles of Ca(OH)2 (0.002 moles of Ca(OH)2) x (74.08 grams/mole) = 0.1 grams = theoretical yield Tube 2: (0.0035 moles of CaCl2) x (1 mole Ca(OH)2/ 1 mole of CaCl2) = 0.004 moles of Ca(OH)2 (0.004 moles of Ca(OH)2) x (74.08 grams/mole) = 0.3 grams= theoretical yield Tube 3 (0.0050 moles of CaCl2) x (1 mole Ca(OH)2/ 1 mole of CaCl2) = 0.005 moles of Ca(OH)2 (0.005 moles of Ca(OH)2) x (74.08 grams/mole) = 0.4 grams =theoretical yield Tube

IV. Data and observations Mass of beaker (g) 174.01 Mass of beaker + NaOH pellets (g) 174.54 Mass of NaOH pellets 0.53 TRIAL 1 TRIAL 2 Mass of potassium acid phtalate (KHP) (g) 0.15 0.15 final buret reading (ml) 30.75

To identify the unknown acid. 4. To determine acid dissociation constant, Ka and pKa for the unknown acid. Introduction: Titration process is used in an acid-base experiment in order to determine the concentrations of solutions of acids and bases.