Purpose:In this activity, we observed how mass is affected in a chemical reaction in which a gas is produced.Hypothesis:If a chemical reaction (IV) produces a gas in an open system lab, the total mass (DV) will be decreased because the gas produced will escape. Safety Precautions:The reaction of hydrochloric acid and sodium hydrogen carbonate may cause splattering. Do not place your hand directly over the beaker when adding the acid to the sodium hydrogen carbonate. Keep your face away from the beaker also.Data and Observations:Total mass of reactants and containers: 132.09gAfter reactants were “mixed”:Bubbles/gas formedVolume increasedContents became opaqueAs substance cleared, volume decreasedBubbles still formingTotal mass of products and containers: 131.78gAnalysis and Evaluation:It was evident that a chemical reaction occurred due to the forming of a new substance and gas being produced.The reactants in this chemical reaction were the sodium hydrogen carbonate and the acetic acid.The total mass decreased by 0.31g. Due to the flask being open, the gas escaped, resulting in contents being released and the difference in mass. To make a fair comparison between the two activities, both activities would have to include sealed flasks as controlled variables.The product could cause the flask to explode due to its outward pressure.Pressure could build up due to the gas produced by the product.Sodium hydrogen carbonate + acetic acid = sodium acetate + water + carbon dioxide              Mixing the two reactants with the beaker in the balance could add to the total volume and provide inaccurate data.Conclusion:Overall, the experiment demonstrated that the total mass of the products decreases when a gas is formed in a chemical reaction. In this activity, a 0.31g difference was observed between the total mass of the products and the reactants. However, this could be accounted for by experimental error and/or inaccurate measurements, which could affect the difference drastically or minimally, depending on the severity of the error.