University:
Missouri State University
Course:
CHM 160 | General Chemistry I
Academic year:

2021
Views:

164

Pages:

2
Author:

Brandon Owen

Lab – Conservation of Mass in a Chemical Reaction When baking soda comes in contact with vinegar, a chemical reaction takes place. Fizzing occurs indicating a gas is produced and the reaction absorbs energy (feels cold to the touch), indicating it is an endothermic reaction. Vinegar is a dilute solution of acetic acid. Vinegar and water are miscible. In addition to carbon dioxide gas, sodium acetate and water are formed. Sodium bicarbonate and sodium acetate are soluble in water (the universal solvent) and are shown as (aq) in the balanced equation. Sodium bicarbonate and sodium acetate are ionic compounds – they each have a metal ion (sodium ion) present. Baking Soda (sodium bicarbonate) + Vinegar → Sodium Acetate + Water + Carbon Dioxide Sodium Hydrogen Carbonate + Acetic Acid → Sodium Acetate + Water + Carbon Dioxide NaHCO3 (S) + HC2H3O2 (aq) + Energy → NaC2H3O2 (aq) + H2O (l) + CO2(g) Purpose: To show that mass is conserved in a chemical reaction and that gases are matter. Procedure: 1.) Mass the empty bottle and cap. 2.) Add about 25 mL of acetic acid solution to a screw top bottle. If the outside of the bottle becomes wet, dry it. 3.) Mass the bottle, cap and the acetic acid. 4.) Measure the mass of a small test tube. 5.) Add solid sodium hydrogen carbonate to the test tube until it is about ¼ full. Determine the mass of the test tube with the solid in it. 6.) Place the test tube (upright) in the bottle containing the vinegar and tighten the cap. 7.) With the bottle sealed, tilt the bottle to mix the reactants. Observe the reaction and record your observations. 8.) When the reaction ceases, mass the bottle and contents (products). 9.) Carefully remove the cap to prevent any liquid from escaping. 10.) Mass the open bottle, contents, and lid. Data Table: Observations Volume of Acetic Acid Mass of bottle and cap Mass of bottle, cap, and acetic acid Mass of TT and Baking soda Mass of TT Mass of Bottle, cap, TT and Reactants Mass of sealed bottle, cap, TT, and Products Mass of unsealed bottle, cap, TT, and remaining products Calculations (Show work): Mass of acetic acid (vinegar) Mass of Baking Soda Total mass of reactants Mass of bottle, cap, TT and reactants Mass of bottle, cap, TT, and products Total mass of products Mass of products remaining in the unsealed bottle Mass of Carbon dioxide Density of Vinegar (D= M/V) % error for reaction. (“accepted” = mass of reactants “experimental” = mass of products) % error = | accepted – experimental | accepted x100 Questions: 1. Did your results reflect a law of conservation of mass? Why or why not? 2. What evidence was there that a chemical reaction took place? 3. What other signs could indicate a chemical reaction took place? 4. Why was the mass of the unsealed bottle and products different than the sealed bottle and products? Conclusion: