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?
- signs of chemical change = changes the shape and color, creates a gas, distributes heat, Etc. - Chemical Change= Substance is formed into a completely new substance 2. Hypothesis: If the copper is being tested in these metals ( Copper, Magnesium and cupric chloride) then it would be the least reactive out of magnesium and zinc because it is the lowest among the three on the activity series. 3. Experimental Design: - Independent Variable: different types of metals: magnesium, zinc and Copper - Dependent Variable: amount of reactants observed for each metal - Control : The Air -Constants: The amount of chemical solutions, the time the metals were in the chemical solutions and size of each metal during the experiment 4.
We need to be able to find the limiting reagent and be able to go through the process of gravimetric stoichiometry. Hypothesis: The limiting reagent will be the strontium chloride due to the calculations and the copper (II) sulphate pentahydrate. My calculations also conclude that we should get 1.378 g of the precipitate of Strontium Sulphate. SrCl2 * 6H2O + CuSO4 *5H2O SrSO4 + CuCl2+ 11H2O I Mole 1 Mole 1 Mole 1 Mole 11 Mole 2g 2g ? Materials: • 2 Graduated Cylinders • Distilled Water • Stirring Rod • Balance • One 250ml Beaker • One Erlenmeyer Flask • Filter Paper • Copper (II) Sulphate Pentahydrate • Strontium Chloride Hexahydrate Procedure 1.
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.
Which of these is the richest source of nitrogen on a mass percentage basis? a) Urea, (NH2)2CO b) Ammonium nitrate, NH4NO3 c) Nitric oxide, NO d) Ammonia, NH3 Cisplatin, an anticancer drug, has the molecular formula Pt(NH3)2Cl2. What is the mass (in gram) of one molecule ? (Atomic weights : Pt = 195, H = 1.0, N = 14, Cl = 35.5) a) 4.98 × 10−21 b) 4.98 × 10−22 c) 6.55 × 10−21 d) 3.85 × 10−22 Aspirin has the formula C9H8O4. How many atoms of oxygen are there in a table spoon weighing 360 mg?
11.Repeat procedure again. Part Two 12.Use the thiosulfate to refill the 50 mL buret. 13.In a Erlenmeyer flask, add 1 mL of bleach. 14.Add this Erlenmeyer flask to 25 mL of distilled water. 15.Dissolve 2g of KI in the flask.
Results : Yield (mass in gram) = __________________0.128 g_____________________ Melting point of pure phenyl benzoate (OC) = ___________70O______________ Melting point of your phenyl benzoate (OC) = ___________69O______________ Questions : 1. Why do we use NaOH solution to dissolve phenol rather than water in step 1 ? Because NaOH can be use to change the phenol to ion form, which can be more soluble in the aqueous
In the fourth part, we determined the exact concentration of EDTA by standardization. Lastly, we determined the hardness of the water. The diluted EDTA titrant was used for the titration of the sample. 10.00 ml of the sample was used instead of the 10.00 ml standard CaCO3. Water hardness is an expression for the sum of the calcium and magnesium cation concentration in a water sample.
I2 is the only species that is undergoing distribution. KI3 and KI are insoluble in the non-polar solvent as they are ionic. The concentration of I2 is related to its KD, or characteristic distribution coefficient. The concentration of I2 in the aqueous layer can be determined by measuring the I2 concentration in the organic layer as long as there is knowledge of KD. the total titratable iodide that was present is greater than the concentration of the I2 in the aqueous phase as some is being bound as I3-.