Stoichiometry Lab Analysis and Calculation

Stoich. Lab Introduction Part I You must incorporate in FULL SENTENCE FORM the following: We have TWO purposes. 1.Determine the amount of precipitate produced in grams. 2.Determine the concentration of the sodium carbonate.  Additional Topics: – Describe the differences between quantitative and qualitative data. Which are we using in this laboratory and why? – Describe volumetric and gravimetric analysis, give general examples we used in the laboratory. – Explain the filtration apparatus general purpose and its’ set-up.

Stoich. Lab Introduction Part II More Topics which MUST be discussed: – Discuss the molarity formula: give the formula, brief description of the variables, and the purpose of molarity. – Explain what are the purposes of molar coefficients (the molar ratio). – (WRITE THIS SENTENCE LAST)  Briefly in one sentence, describe specific experiment.

Materials List & Procedures MATERIALS: – In your materials, list those ONLY USED IN LAB. – Draw the Filtration Apparatus AFTER the list of materials with appropriate labels. PROCEDURES: – Simply summarize all procedures as appropriate.

Data Table Your Data Table MUST include: – Na 2 CO 3 mL used – CaCl 2 mL used – Weight of filter paper alone – Weight of [filter paper + precipitate] – Weight of precipitate alone

The Data Analysis of Stoich. Lab There are five parts to the Data Analysis section. You MUST include a heading for each part. After the heading, you will show the appropriate work. 1.Identify the solid white precipitate (What compound did we produce in lab?) 2.Obtain the final weight of the white precipitate (How much does it weigh & first purpose of lab) 3. Convert to moles of the sodium carbonate (with moles of sodium carbonate can determine the concentration) 4.Calculate the molarity of the sodium carbonate (The second purpose of the lab) 5.Determine the percent Error for the Molarity (How accurately did you perform the experiment?)

Part 1: Identify the white precipitate What is the predicted precipitate according to Solubility Rules? Basic Eq: SrCl 2(aq) + Na 2 CO 3(aq)  SrCO 3(s) + 2NaCl (aq) The precipitate will be, strontium carbonate. Ionic Eq: MUST be in laboratory report Net Ionic Eq: MUST be in laboratory report

Part 2 & 3 of Data Analysis Section Part 2: The weight of the precipitate. [filter paper + precipitate] – filter paper = precipitate (grams) Part 3 : The moles of sodium carbonate Use the Basic Eq: SrCl 2(aq) + Na 2 CO 3(aq)  SrCO 3(s) + 2NaCl (aq) obtained g SrCO 3 x 1 mol SrCO 3 x 1 mol Na 2 CO 3 = moles Na 2 CO g SrCO 3 1 mol SrCO 3 Conversion Keys: 1 mol of SrCO 3 = g SrCO 3 1 mol SrCO 3 = 1 mol Na 2 CO 3

Part 4: Molarity of the sodium carbonate To determine the molarity of the solution, we use: M = mol of solute = mol of moles Na 2 CO 3 L of solution L of solution Add the used Na 2 CO 3 solution in mL, then convert to Liters Apply liters of sodium carbonate and mol of sodium carbonate back into the molarity formula:

Part 5: Percent Error Once determining the experimental Molarity of Na 2 CO 3, compare to expected value. Percent Error = 100 x Your Result – Accepted Value Accepted Value

Review - Road Map for Stoich. Lab Survival 1 & 2 Predict the Precipitate, convert to moles of precipitate 3 Use Molar Ratio to obtain moles of sodium carbonate 4 Add up how much sodium carbonate was used in the lab Apply the Molarity formula and find the Molarity of the sodium carbonate 5 Determine the Percent Error for the molarity!