Saul Ruiz Experiment 4 October 30 2011 Determination of a Chemical Formula The purpose of this experiment is to determine the chemical formula of a certain compound using a method known as titration In order to do so the metal is reacted with water and an acid and the result should be the formation of a precipitate As for the general procedure zinc and calcium are mixed with both water and hydrochloric acid HCl in order to observe the reaction and determine if a precipitate is present One thing to be noted is the difference in the molarity used in the experiment Zinc is diluted with 6M of hydrochloric acid whereas calcium is diluted with 0 02 M of hydrochloric acid When zinc is diluted with 6M of HCl the reaction resulted in an endothermic reaction since the match s flame was absorbed A slight popping sound also occurs which shows that hydrogen gas is present Zinc and water on the other hand only produced minute bubbles Calcium and the 0 02M of hydrochloric acid created a similar reaction as zinc and hydrochloric acid with the solution absorbing heat and releasing gas as a result Finally the reaction between calcium and water produces gas calcium hydroxide and heat Zinc 6M HCl 2 s 2 HCl aq Zn Cl 2 aq H 2 g Molecular Zn aq H 2 g Net Ionic 2 H Calcium 0 02M HCl Molecular Ca s 2 HCl aq Ca Cl2 aq H 2 g aq H 2 g Net Ionic 2 H Zinc Water 2 s 2 H 2 O l Zn OH 2 aq H 2 g Molecular Zn aq H 2 O l aq H Net Ionic OH Calcium Water Molecular Ca s 2 H 2 O l Ca OH 2 aq H 2 g aq H 2 O l aq H Net Ionic OH By knowing the initial mass of the metal and mass of the acid needed to neutralize the solution the chemical formula can be calculated It is calculated by finding out the ratio of calcium to hydroxide used in the experiment The net ionic equation that shows the neutralization of the solution is aq H 2 O l aq H OH The results obtained from this experiment were somewhat innacurate The calculated molecular formulae were Ca OH 1 51 and Ca OH 1 79 The true chemical formula was actually Ca OH 2 In conclusion the purpose of this lab was to determine a chemical formula of a particular compound In order to do this metal water and acid react together It is needed to see if a reaction gas is produced If there is a reaction the amount of acid needed to neutralize the metal that was reacted in water will help determine the ratio of metal and hydroxide which would give you the chemical formula Some possible sources of error include contaminated water the oxidation of the metal with the air the metal not completely reacting with the water and inaccurate measurements such as air bubbles in the burette when pouring acid in the solution To minimize these errors it is necessary to weigh the calcium and place it in the water quickly