This lab will teach us how to identify several different substances that may be present in tap water and ocean water using different chemical tests. It will also show us the presence of solids in both tap water and ocean water.
9.Test Tube #3: a) Ca + CO3 -> CaCO3 b) Mg + CO3 -> MgCO3
10.Test Tube #4: Ag+ + Cl- -> AgCl(s)
11.Test Tube #5: Ba + SO42- -> BaSO4
12.Test Tube #6: Pb + HCl -> PbCl2(s) + H+
Weight of Residue = (Original Weight) – (Weight after boiling)
151.734g – 151.726g = 0.008g
%Total solids in Tap Water = (Grams of residue) / (Grams of original solution)
0.008g/(223.238g-151.726g) = 0.008g/75.512g = 0.011%
ppm = (mg solute) / (Liters Solution)
8mg/(0.075L) = 100ppm
The purpose of part one of this experiment was to observe the presence of solids in the local tap or ocean water. To do this we boiled 75mL of tap water in a beaker. We compared the masses of the beaker before water was added, and after it was evaporated to determine the weight of the remaining residue. We obtained a light crusty brown residue at the bottom of our beaker. It was found to weight only 8mg, which means the local tap water has very little solids.
Still looking at tap water, part two was to determine the presence of several different elements. We used a variety of different chemical solutions and observed their reactions when added to tap water. The water contained no nitrate ions because there was no reaction with iron (II) sulfate and sulfuric acid. However, we did get to see what it would look like if nitrate was present because in one sample we added HNO3. Both calcium and magnesium were present because when added ammonium carbonate to our sample it formed calcium carbonate and magnesium carbonate as can be seen in the following balanced equations: Ca + CO3 -> CaCO3, Mg + CO3 -> MgCO3. Chloride was also present because when we added nitric acid and silver nitrate, silver chloride was formed as can be seen in the balanced equation: Ag+ + Cl- -> AgCl(s).
Over time, numerous applications for the addition of salt in water have been established and the process of adding salt in water has become a regular exercise wherever water has to be boiled around the world (Bradley, 2006). Purpose The purpose of this project is to study the implications of the addition of salt in the reaction of water to heat. Theory & Hypothesis Upon the addition of common ...
Sulfate was also present because when we added barium nitrate, barium sulfate was formed as can be seen in the balanced equation: Ba + SO42- -> BaSO4. Lead was not present in our sample because when hydrochloric acid was added, lead (II) chloride was not observed as it would if lead was present as can be seen in the balanced equation: Pb + HCl -> PbCl2(s) + H+.
I found the second part especially interesting. It is good to know our tap water does not contain lead or nitrate, since both are toxic to humans. I would assume that calcium, magnesium, chloride, and sulfate were either added or allowed to remain by the local water authorities because they are good for humans in small quantities.[/img]