Homework Sourse1 A field geologist carries a dropper bottle of a strong aci
1. A field geologist carries a dropper bottle of a strong acid, HCI(aq), to help with the identification of samples. A rock is found to give off odorless gas bubbles when a few drops of the acid are added. Which anion is mostly likely in the rock?
2. Two common substances that are used in the northern U.S. to melt snow and ice are sodium choride (rock salt) and calcium chloride. You have a bag of a substance sold as melting salt. Outline a short procedure that will identify if one of these compounds is contained in the bag and, if so, which one.
1. A field geologist carries a dropper bottle of a strong acid, HCI(aq), to help with the identification of samples. A rock is found to give off odorless gas bubbles when a few drops of the acid are added. Which anion is mostly likely in the rock?
2. Two common substances that are used in the northern U.S. to melt snow and ice are sodium choride (rock salt) and calcium chloride. You have a bag of a substance sold as melting salt. Outline a short procedure that will identify if one of these compounds is contained in the bag and, if so, which one.
Solution
1.)Zinc
2.)There is no way to do it directly. What you can do is precipitate the calcium as an insoluble salt, filter it off, and then evaporate off the solvent to obtain solid NaCl. Addition of ammonium carbonate should do the trick.
CaCl2 + (NH4)2CO3 ? CaCO3(?) + 2NH4Cl
Filter off the calcium carbonate and heat the filtrate to drive off the ammonia, leaving a solution of NaCl in dilute hydrochloric acid. Evaporate off the solvent to leave NaCl crystals.
React the calcium carbonate with hydrochloric acid and evaporate off the excess, along with the water. This will yield CaCl2 in return.
CaCO3 + 2HCl ? CaCl2 + CO2 + H2O
