Semih Durmuş
February 29, 2003
PREPREATION OF CALCIUM CHLORIDE
AIM: To produce a sample of this salt free from contamination, from reactants or other products of the reaction.
OBSERVATION
Reaction: When I put hydrochloric acid “HCI” into 100 ml beaker, its doesn’t have colour; it is transparent. Then, I added a little bit calcium chloride “CaCO3” into the beaker, which had hydrochloric acid. First, hydrochloric acid effervesced a little bit, and its colour became a little whitish. It had shown that hydrochloric acid had reacted to CaCO3(Because, CO2 is gotten with the reaction and it effervesces) . After that I added more calcium carbonate and it effervesced again, and its colour became more whitish. It was becoming white because, when HCI acid reacted to CaCO3, aqueous solution of calcium chloride, whose colour was white, was being produced. Also, carbon dioxide “CO2” was being produced with the reaction so hydrochloric acid was effervescing.
I continued to put calcium carbonate into the beaker. After a few minutes, some particles of powdered calcium carbonate had remained. At that time the reaction had been completed, because there were no more hydrochloric acid to react powdered calcium carbonate, so calcium carbonate particles had remained. Also, when the reaction had been completed, the colour was completely white- like milky.
Final Product: When the reaction had been completed; calcium chloride “CaCl2”, water “H2O”and carbon dioxide “ CO2” had been produced, carbon dioxide had gone into the air, and water and calcium chloride had remained in the beaker. However, there were some excess calcium carbonate particles that didn’t react in the beaker so I filtered this mixture- aqueous calcium chloride and calcium carbonate particles. Then, calcium carbonate remained in the filter as a kind of whitish mud and aqueous calcium chloride was collected in the evaporating basin. When I started to heat it, the water vaporized and calcium carbonated, whose colour is dirty white, started to remain in the beaker as solid compound. At the end, it swelled on the evaporation basin, and when touched it caved in.
RESULTS
· Volume of Alcohol: 100 ml
· Mass of Evaporation Basin: 45.876 gram
· Mass of Evaporation Basin + Calcium Chloride(s) : 48.481gram
48.481-45.876= 2.605 gram (The Mass of CaCI2)
CaCo3(s) + 2 HCI (aq.) CaCl2 (aq.) +H2O (aq.) + CO2 (g)
COCLUSION
The result I found isn’t so accurate because it is 93% right, it isn’t 100% right. It shows that some errors changed my result because even though I used a very accurate balance that could measure three digits after decimal place, I couldn’t get very accurate a result. Therefore, it shows that some errors changed the result.
One of the errors is filtrating error. It doesn’t filtrate accurately. Therefore, some calcium chloride “CaCl2” solution remains at top of the funnel. Therefore, less CaCl2 is gotten in the evaporating basin and when the water vaporizes and “CaCl 2” is remained in basin, the mass becomes fewer. Also, when the filter filtrates the mixture, the aqueous solution of calcium chloride “CaCl2” passes from the filter and drops to the basin and particles of excess calcium carbonate remains on the filter paper but thru at the end of the filtration, this particles fills the entrance of the funnel. Therefore, some aqueous solution of calcium chloride remains at the top of the filter paper.
Another error is that beaker isn’t precision. It is important because it cause less or more usage of HCI. If more or less HCI is used, more or less CaCl2 is gotten. Also, the mixture is flown in a few beakers therefore, in every step, solution is lost. For example, acid is taken into a 100 ml beaker than when it reacts to calcium carbonate, it is flown into the funnel and then into evaporating basin. Therefore, the amount decreases a little bit in every step of the experiment.