Add 1 mL of deionized water to the small test tube containing the precipitate and mix it and centrifuge it for 60 seconds. Then, add the supernatant into the boiling test tube and repeat this step one more time with another 1 mL of deionized water. Acquire a pair of metal test tube holders and heat the boiling test tube to evaporate the water for 15 minutes. Let is cool after and weigh it. Then, calculate a percent yield of zinc iodide and write a balanced chemical equation and determine the limiting
b. Once again, place assembly in water bath and begin to heat c. When acetamide has begun to melt, record the temperature. d. Let assembly cool down and record temperature when acetamide begins to recrystallize. e. Repeat process two more times. Data: Data Table 1 | | | Rubbing Alcohol Trial # | Boiling Point | Percent Error | 1 | 79.5 C | 3.52% | 2 | 84.0 C | 1.90% | 3 | 83.5 C | 1.30% | Data Table 2 | | | | Acetamide Trial # | Melting Point | Freezing Point | Percent Error (Melting Point) | 1 | 79.5 C | 57.5 C | 3.50% | 2 | 80.5 C | 59.5 C | 0.60% | 3 | 78.0 C | 61.0 C | 3.70% | Observations: It was observed that thermometer placement could affect the readings in the water bath.
Add a quarter spatula of copper (II) oxide and warm the solution gently to the 4th test tube and record observations. 7. To the 5th test tube, add 3cm3 of ethanol a couple of drops of conc, sulphuric acid and warm gently. Pour the resulting mixture into 30cm3 of sodium carbonate solution to remove excess acid and smell and record observations. Experiment 2 Time | Observations | 5 minutes | Bubbled like sugar | Once salt water was added | Turned soapy white and thick | Equation: METHOD 1) Put 2 cm3 of castor oil into a 250 cm3 beaker and add 10 cm3 of 5mol.dm-3 sodium hydroxide from a measuring cylinder.
0.00512 * 500 = 2.56 c. 0.00806 * 319.9= 2.56 d. 0.00806 * 319.9 = 2.56 500 mL =0.5 L e. 0.0161 * 500 / 2 =2.56 4. Exercise 4: a. 0.250M; 250 mL 0.25 L (0.25) (0.25) = 0.0625 moles ZnI2 b. Prepare the solution by dissolving 19.95 grams of Zinc Iodide with 250 mL of water. c. Prepare the solution by dissolving 38.90 grams of ZnI2 with 500 mL of water.
CHEM 1412 SAMPLE FINAL EXAM PART I - Multiple Choice (2 points each) _____ 1. In which colligative property(ies) does the value decrease as more solute is added? A. boiling point B. freezing point and osmotic pressure C. vapor pressure D. freezing point and vapor pressure _____ 2. What is the molarity of a solution prepared by dissolving 25.2 g of CaCO3 in 600 mL of solution? A.
INT Task 3 Problem Statement: The purpose of my experiment is to test the Mpemba Effect, which states that under certain circumstances hot water will freeze faster than cold water. Relevance of your testable question: This experiment is relevant in order to help specify the conditions under which the Mpemba Effect will occur. This experiment has been widely reproduced since its discovery in 1963 by Erasto B. Mpemba, but it’s still not completely understood. Literature Review: The first case study was taken from scienceoffcenter.org. The experimenter used 3 identical plastic cups and filled one with room temperature tap water, one with warm tap water and one with boiling tap water.
Calculate the molarity of the original vinegar solution and its concentration in gdm-3, given that it reacts with NaOH in a 1:1 ratio. 7. 2.5 g of a sample of ethanedioic acid, H2C2O4.nH2O, was dissolved in water and the solution made up to 250 cm3. This solution was placed in a burette and 15.8 cm3 were required to neutralise 25 cm3 of 0.1 moldm-3 NaOH. Given that ethanedioic acid reacts with NaOH
Part 1: Scemario 4 Carmen conducted an experiment to determine whether salt added to a cup of water affects its freezing point (the temperature at which it freezes). After some research, she hypothesized that the greater the amount of salt dissolved in the water, the lower the temperature at which the water freezes. Water samples were prepared containing equal quantities of water at the same starting temperature. Each sample received a different amount of salt and was placed into a freezer. The length of time it took for each sample to freeze was recorded as shown below.
Eighth, and last, I found molecular weight of sugar and diluted it. Data Tables and Observations: Data Table 1: Length measurements. | Object | Length (cm) | Length (mm) | Length (m) | CD or DVD | 5.2 | 52.0 | .052 | Key | 12.0 | 120.0 | .120 | Spoon | 18.6 | 186.0 | .186 | Fork | 21.0 | 210.0 | .210 | Data Table 2: Temperature measurements. | Water | Temperature (°C) | Temperature (°F) | Temperature (K) | Hot from tap | 46 | 114.8 | 319.15 | Boiling | 100 | 212 | 373.15 | Boiling for 5 minutes | 100 | 212 | 373.15 | Cold from tap | 18 | 64.4 | 291.15 | Ice water – 1 minute | 0 | 32 | 273.15 | Ice water – 5 minutes | 0 | 32 | 273.15 | Data Table 3: Mass measurements. | Object | Estimated Mass (g) | Actual Mass (g) | Actual Mass (kg) | Pen or pencil | 5 | 5.4 | .0054 | 3 Pennies | 6 | 7.6 | .0076 | 1 Quarter | 5 | 5.7 | .0057 | 2 Quarters, 3 Dimes | 15 | 18.2 | .0182 | 4 Dimes, 5 Pennies | 15 | 21.6 | .0216 | 3 Quarters, 1 Dime, 5 Pennies | 25 | 31.9 | .0319 | Key | 10 | 9.2 | .0092 | Key, 1 Quarter, 4 Pennies | 20 | 24.9 | .0249 | Data Table 4: Liquid measurements.
(Make a rough titration first). 5. Calculate the moles and mass of acetylsalicylic acid in an aspirin tablet. Determine the mass percentage of acid in a tablet. Data collection VolumeV / cm3 | Titration trials | | | | 1 | 2 | 3 | 4 | 5 | Initial burette reading V / cm3±0.05 cm3 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | Final burette reading V / cm3±0.05 cm3 | 13.6 | 13.9 | 14.0 | 13.9 | 14.1 | Total tire V / cm3 ±0.1 cm3 | 13.6 | 13.9 | 14.0 | 13.9 | 14.1 | Table 2 Volume of HNO3 required titrating NaOH in excess Mass of aspirin tablet ±0.001 [g] | 3.229 | 3.143 | 3.142