April 7th, 2015
Investigating Stoichiometry with Sodium Salts of Carbonic Acid Introduction-
This experiment is intended to help find a better understanding of chemical stoichiometry through titrations of NaHCO3 and NA2CO3 with HCl. A chemical reaction is a process that involves rearrangement of the molecular or ionic structure of a substance, as opposed to a change in physical form in a nuclear reaction. Titration is when a measured amount of solution of unknown volume is added to a known volume of a second solution until the reaction between them is complete. The objective of this experiment is reacting sodium bicarbonate (NaHCO3) and sodium carbonate (NaCO3) with hydrochloric acid (HCl) to produce sodium chloride (NaCl), water (H20) and carbon dioxide (CO2). -Use the titrations of the following chemical reactions:
NaHCO3 + HCl (aq) NaCl (aq) + H2O (l) + CO2 (g)
2HCl (aq) + Na2CO3 (s) 2NaCl (aq) + H2O (l) + CO2 (g)
Two Erlenmeyer flask must be labeled “unknown 1 and unknown 2”. Assure that all containers used are dried and cleaned properly. Two bigger flask are labeled “waste” according to each unknown. A pipette is set up and primed with HCl. The two unknown solids are weighed to a mass of 0.15g each. The unknown solids are dropped carefully into the corresponding Erlenmeyer flask wit 50mL of distilled water. The solid in the water must be dissolved and afterwards add 10 drops of Bromecresol green to indicate the change of color when the solution has been titrated. The flask should start with a blue tint. HCl is carefully dropped into the Erlenmeyer flasks with the primed pipette until the solution turn to a green tint. Once the green tint has been achieved, drop one or two more drops of HCl to the solutions until the tint turns yellow. The flask is heated until all of the water has evaporated from the flask, leaving solid remains of NaCl. The flask is weighed with...
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