Lab Report of Hydrate

Formula of a Hydrate

1. INTRODUCTION

Hydrates are ionic compounds such as salt that assumes specific amount of water molecules as part of their crystal formation. This water can be driven off by the appliance of heat. The percentage of water should be the same for each sample since the ratio of the ionic compound to water compound is always the same this chemical is called calcium sulfate trihydrate. When you find the mass of this chemical, you find the mass of the calcium sulfate and then add 3 times the mass of water to it. Since water can easily be removed from a hydrate just by heating strongly, one can now find the percent of the anhydrous salt (salt without the presence of water) and the water. One can find out number of moles of water present in per mol of anhydrous salt, by finding a mol ratio.

2. PROCEDURE

1) Clean and dry the crucible. From this point on throughout the experiment, handle the crucible and cover with clean crucible tongs only. (Points up to carry crucible points down to carry lid)

2) Place the crucible and cover on the triangle as shown by our instructor. Position the cover slightly tipped, leaving only a small opening for any gases to escape. Preheat the crucible and cover to redness.

3) Allow the crucible and cover to cool for about 5 minutes. (Never place a hot crucible on a balance) When it's cool, use the tongs to transfer the crucible and cover to the triple beam balance and determine the mass of the crucible and cover to the nearest 0.01-g. Record this mass in your data table.

4) Obtain approximately 5 g of magnesium sulfate hydrate crystals from your instructor. Determine the mass of the covered crucible and crystals to the nearest 0.01 g. Record this mass in your data table.

5) Place the crucible with the magnesium sulfate hydrate on the triangle and again position the cover so there is only a small opening. Too large an opening may allow the hydrate to spatter out of the crucible. Heat the crucible very gently for several minutes on a low flame to avoid spattering any of the hydrate. Increase the temperature gradually for 2 to 3 minutes. Then heat strongly, (red- hot) for at least 5 minutes. Allow the crucible, cover, and contents to cool for 5 minutes and then determine their mass. (Record this mass in your Data table)

6) Heat the covered crucible (slightly ajar) and contents again to redness for 5 minutes. Allow the crucible, cover and contents to cool for 5 minutes and then determine their mass. If the last two masses determinations differ by no more than .01 g you may assume all the water has been driven off. Otherwise repeat the heating process until the mass no longer changes. This means all the water has been driven off. Record this constant mass in your data table. The dehydrated compound left in the crucible should be returned to the collection