LAB #4:  UNKNOWN FERRIC COMPOUND

SAFETY PRECAUTIONS:
Wear chemical splash goggles at all times. Avoid contact of all chemicals with eyes and skin and wash hands thoroughly with soap and water before leaving the laboratory. Please follow all laboratory safety guidelines.

Introduction

In this experiment we will use stoichiometric principles to deduce the appropriate equation for the reaction between metallic iron and a solution of copper (II) sulfate. This reaction produces metallic copper, which is seen precipitating as a finely divided red powder. This type of reaction, in which one metal "displaces" another from a solution of one of its salts, is known as a single replacement reaction. A metal capable of displacing another from a solution of one of its salts is said to be "more active" than the displaced metal. In this experiment, iron is more active than copper.

Iron forms 2 types of ions, namely Fe+2 and Fe+3. We shall use stoichiometric principles to determine which of these ions is formed in the reaction between iron and copper (II) sulfate solution. If Fe+2 is formed, then equation (1) is correct, while equation (2) is correct if Fe+3 is formed. Your task is to find out which equation is consistent with the results of your experiment.

(1)        Fe(s) + CuSO4 (aq)  FeSO4 (aq) + Cu(s)
Fe(s) + Cu+2(aq)  Fe+2(aq) + Cu(s)

(2)       2 Fe(s) + 3 CuSO4 (aq)  Fe2(SO4)3 (aq) + 3 Cu(s)
2 Fe(s) + 3 Cu+2(aq)  2 Fe+3(aq) + 3 Cu(s)

An excess of copper (II) sulfate solution (to make sure that all the iron is reacted) will be added to a known amount of iron. The metallic copper produced will be weighed. These weighings will be used to calculate the moles of iron used and the moles of copper formed. If equation (1) is correct, the moles of copper should equal the moles of iron. If equation (2) is correct, we should obtain 1.5 moles of copper per mole of iron.

Pre-Study

As part of your pre-lab preparations, complete the following pre-study worksheet

This worksheet goes through the calculations of a similar experimental set-up.  You will need to upload a copy of this worksheet to Canvas and manually input the answers on the pre-lab quiz.

Procedure

Read and review carefully the procedure handout attached at the very bottom of this page.  Questions about the procedure may be included on the Pre-Lab Quiz.

After reviewing all the content on this page and any attachments and videos, complete the Pre-Lab Quiz:
Access Pre-Lab Quiz here.

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Bryan Dunn,
Sep 7, 2018, 5:43 AM