Limiting Reactants

Good Essays
Chemistry 101 Lab 7 Determination of % NaHCO3 in Alka Seltzer Tablets

Names ____________________________and ___________________________
Date ____________________________

Objectives:
(1) To determine the amount of NaHCO3 in Alka Seltzer tablets by observing the amount of CO2 produced from the acid-base reaction of HCO3- with acetic acid (in vinegar).

(2) To study the concept of limiting reactant.

Background:
Alka Seltzer is an effervescent tablet that contains aspirin (acetylsalicylic acid), citric acid, and sodium bicarbonate (NaHCO3). As soon as the tablet dissolves in water, the NaHCO3 dissociates to form a bicarbonate ion (HCO3-) and a sodium ion (Na+)

1. NaHCO3(s)  Na+(aq) + HCO3-(aq)
Acetic acid, which will ‘donate’ H+ to water to create H3O+(aq) is then added to the mixture. With the addition of acetic acid the following acid-base reaction then takes place:

2. HCO3-(aq) + H3O+(aq)  2H2O(l) + CO2 (g)

(The sodium ion does not take part in this reaction, and so is not included in the equation.) According to the reaction equation, one mole of HCO3- reacts with one mole of H3O+. If the number of moles of each reactant is not the same, then one reactant will be completely used up during the reaction while some of the other reactant will remain at the end of the reaction. The reactant that is completely used up is called the “limiting reactant”. In this experiment you will dissolve Alka Seltzer in various concentrations of vinegar and measure the amount of CO2 produced. From this data you will calculate the amount of NaHCO3 in the Alka Seltzer by percent weight. You will also determine the limiting reactant at each concentration.

Pre-lab Question:

a) What are the bubbles that form when Alka Seltzer is dissolved in water? Give the chemical formula.

b) What is the ratio of moles of CO2 produced to moles of NaHCO3 reacted?

Procedures:
1. Using a 50 mL graduated cylinder,

You May Also Find These Documents Helpful

  • Satisfactory Essays

    Limiting Reactant Lab

    • 397 Words
    • 2 Pages

    During this lab, we found the excess reactant and limiting reactant between Aluminum and Copper (ll) Chloride. Using stoichiometry, we were able to make predictions. Through the reaction 2Al + 2CuCl₂ → 3Cu + 2AlCl₃ we carried out this experiment and determined that the limiting reactant was CuCl₂ and that the aluminum was in excess. We also determined the percentage yield of copper. Purpose: The purpose of this experiment was to determine the limiting reactant and percentage yield of the reaction…

    • 397 Words
    • 2 Pages
    Satisfactory Essays
  • Good Essays

    Limiting Reactant Lab

    • 1092 Words
    • 5 Pages

    The Relationship between Reactants and Products Introduction In a chemical reaction, the amount of starting material for a chemical reaction limits the amount of product that can be formed.1 The principle of limiting reactants relates to this lab because the limiting reactant is the substance that is used up first in a chemical reaction. The amount of product was limited by that reagent. The excess reactants were considered to be the other reagents that were presented in excess of the quantity that…

    • 1092 Words
    • 5 Pages
    Good Essays
  • Good Essays

    Observing a Limiting Reactant An experiment was carried out to predict the limiting reactant in a chemical reaction between Magnesium and Hydrochloric acid, using the mole concept. Limiting Reactant: It is the reactant that will deplete or will be used up first during a chemical reaction. Limiting reactant also determine how long the reaction will last for. Balanced Equation: Mg + 2HCl = MgCl2 + H2 The balanced equation is needed to determine the mole ratio between the two reactants. From the…

    • 678 Words
    • 3 Pages
    Good Essays
  • Good Essays

    Limiting Reactants Lab

    • 639 Words
    • 3 Pages

    LMounika Alluri Chemistry HL Block D 19/9/12 LAB REPORT #1 LIMITING REAGENTS INVESTIGATION Aim: To determine the limiting reagent and percent yield of the reaction between potassium iodide with lead (II) nitrate solution. Apparatus required: Safety glasses, funnel stands, watch glass, oven, electronic balance, wash bottle with distilled water, test tubes, 10.0mL 0.50M lead (II) nitrate, 10.0mL 0.30M of potassium iodide solution, two 100.0 mL beakers, funnel, filter paper. Reaction…

    • 639 Words
    • 3 Pages
    Good Essays
  • Good Essays

    caused by different limiting reactants. A precipitate results in a solid formed by an ionic compound. Calcium nitrate and copper sulfate will be added to separate beakers with approximately half of the solutions from the Büchner funnel system of each trial to test for the formation of precipitates. The limiting reactant is the reactant that will run out first in the chemical reaction. It is important to recognize which chemical or compound is the limiting reactant because the reactant in short supply…

    • 792 Words
    • 4 Pages
    Good Essays
  • Powerful Essays

    Experiment #8: Limiting Reactant Abstract In chemical reactions, the significance of knowing the limiting reactant is high. In order to increase the percent yield of product, increasing the limiting reactant, possibly, is the most effective. In this experiment we were able to calculate limiting reactants from the reaction of CaCl2. 2H2O + K2C2O4.H2O(aq). As a group, we obtained our salt mixture of calcium chloride and potassium oxalate, and weighed the mixture. We were able to make an aqueous…

    • 1743 Words
    • 6 Pages
    Powerful Essays
  • Satisfactory Essays

    In a chemical reaction the reactant that runs out first is called the limiting reactant. A personal example would be when I am making candles. I have melted 20 lbs. of wax that yield 24 16 oz. size candle jars. As I am gluing the wicks into the jars I realize that I only have 20 wicks and I need 24 for the amount of wax that I have melted. This means that the wicks are the limiting reactant in my candle making.…

    • 83 Words
    • 1 Page
    Satisfactory Essays
  • Good Essays

    and background In an experiment, limiting reactant affect the “amount of the product.” In the other way, the product this reaction produce dependent on the limiting reactant. For example, 1000kg O2 and 1 gram H2 to form water. In this case, the 1 gram of H2 will be the limiting reactant. Same thing in displacement reactant. If one of the reactants is (Mole) less than the other one, then that reactants becomes the limiting reactants. Once the limiting reactants will completely be ran out of, the…

    • 706 Words
    • 3 Pages
    Good Essays
  • Good Essays

    Determining the Limiting Reactant and Percent Yield in a Precipitate Reaction (SMG 6D) AP Chemistry One example of a double replacement (metathesis) reaction is the mixing of two solutions resulting in the formation of a precipitate. In solution chemistry, the term precipitate is used to describe a solid that forms when a positive ion (cation) and a negative ion (anion) are strongly attracted to one another. In this experiment, a precipitation reaction will be studied. Stoichiometry…

    • 1310 Words
    • 6 Pages
    Good Essays
  • Good Essays

    Determining the Limiting Reactant and Percent Yield in a Precipitation Reaction Objectives: Observe the reaction between solutions of sodium carbonate and calcium chloride. Determine which of the reactants is the limiting reactant and which is the excess reactant. Determine the theoretical mass of precipitate that should form. Compare the actual mass with the theoretical mass of precipitate and calculate the percent yield. Materials: Balance 0.70 M sodium carbonate solution, Na2CO3(aq)…

    • 800 Words
    • 4 Pages
    Good Essays