4. If you had walked into the lab, only to discover that you only had 0.1 M sulfuric acid available to run your tests, how might this have affected your
Calculate the percent error in the molar mass value. Enter both values in the Data Table. Molar Mass Na2CO3 = 105.99 g/mol – this is the closest molar mass to what I calculated, so the unknown M2CO3 must be sodium carbonate. Percent Error: 93.08g/mol – 105.99 g/mol (100) = 12.18% error 105.99 g/mol DISCUSSION Review the procedure and list the possible sources of error that would cause either the molar mass of the unknown to be (a) too high or (b) too low. The goal of this lab was to discover the unknown group 1 metal (M) of the compound M2CO3 by dissolving the compound in water and adding a solution of calcium chloride, CaCl2 to the solution in order to precipitate the carbonate ions to reveal the molar mass of the unknown element, thus determining the identity of the unknown element.
It binds with starch so the more starch, the darker the solution was. We also used a blank solution with no starch to set the spectrometer to zero. The spectrometer was used to compare the absorbency of the starch in the control solutions and the non-control solutions over time. Amylase was the last solution added to start the initial breakdown of the starch. Adding it at one minute intervals allowed the students to see how much starch the amylase was actually breaking down over time.
Indirect Gravimetric Determination of a Hydrated Compound in a Mixture Morgan Dufer I. The purpose of this lab was to find the percent of BaCl2*2H2O in a sample of unknown composition by using gravimetric analysis. II. Pre-lab Questions 1. What mass of MgCO3 is contained in a 2.750g solid sample consisting of only MgCO3 and MgO if heating to decompose all the MgCO3 according to the following equation leaves a solid residue weighing 2.160g?
At this point the volume of base used to neutralized the acid can be determined. Phenolphthalein is the indicator which is colorless in an acid but changes to a faint and permanent pink color in base. The purpose of this experiment is to prepare a sample for titration with a base, become familiar with a buret while using proper titration technique in reaching an end point. Hypothesis : If I titrate a base of known concentration with an acid of unknown concentration then I can determine the concentration can be calculated because of the titration calculation. Materials : • Vinegar • Two small beakers (150mL) • 250-mL Erlenmeyer flask • 10-mL graduated cylinder • 50-mL buret • Buret clamp • Small funnel • M NaOH Hazards : • Chemical spill • Broken glass
Use your answers to Questions 1 and 2 to explain how a water-insoluble organic acid might be freed of non-acidic impurities. Water-insoluble organic acid can be freed of non-acidic impurities by adding strong base into it during fractional distillation. The water-insoluble organic acid will react with the strong to produce an ionic salt which is soluble in water. On the other hand, water-insoluble organic acid which are slightly soluble in water can be extracted by aqueous base from solution in an organic solvent. The fact that organic acid are weak acids and only partially dissociates in
Answer: b. Answer: c. Answer: d. Answer: 3. In an abandoned laboratory has been found a flammable liquid, A, in a bottle bearing only the label “Compound A: [pic].” Government agents have offered you a considerable sum to determine the structure of this compound. After verifying the molecular formula by elemental analysis, you find that Compound A reacts with 1 mol equiv of hydrogen; and, after treatment with acidic [pic], Compound A gives the dicarboxylic acid C (see below). Another bottle from the same laboratory is labeled “Compound B (isomer of A).” Compound B also reacts with 1 mol equiv of hydrogen, but yields cyclohexanone after treatment with acidic [pic].
Experimental Data: The original weight of the mixture before separation was 4.6g. After separation the weights were as follows Grams Percent of mixture Iron Filings 1.4g 33% Sand 1.2g 28% Table Salt 0.8g 18% Benzoic acid 0.9g 21% TOTAL 4.3g 100% IV. Observations: The easiest part of this experiment was separating out the iron filings. With the magnet they separated out pretty easily. When almost boiling the sand, salt, and benzoic acid it didn’t seem like it was working.
As for endothermic the reactions pulls in energy and makes it cold to touch. The other experiment measured the pH level in the reaction. The reaction consisted of sodium hydroxide and hydrochloric acid also to see at which point the reaction becomes neutralized. Neutralization is a reaction between an acid and a base forming a salt and water even tho you can’t see the salt due to the salt dissolving into the solution and the pH level of the reaction around level 7 and has a green sometimes yellow colour when the universal indicator is added. The neutralization gap shows how small the gap is to make the reaction neutral.
Manufacturers of soft drink commonly used benzoic acid or sodium benzoate as food preservatives. Non diet soft drinks lack aspartame, a sugar substitute used in diet soft drinks. Benzoic acid is converted into its salt sodium benzoate through neutralization with sodium hydroxide. Sodium benzoate is rather used than benzoic acid as anti-microbial agent in food and beverages because of the solubility effect. Sodium benzoate is approximately 200 times more soluble than benzoic acid.