Reactivity of metals in single-replacement reactions

Problem:

Which metals will replace each other in single-replacement reactions?

Materials (per group)

four small pieces of each metal: copper, magnesium, and zinc

dilute solutions of metal nitrate salts: Zn(NO3)2 , Ag(NO3), Cu(NO3)2 , Mg(NO3)2

plastic sheet

Safety:

All nitrates are caustic. Avoid contacting them with your skin, and wash immediately if they come in contact with your skin.

Silver nitrate, in particular, will permanently stain your skin. A brown patch will form where skin is exposed to silver nitrate, first appearing several hours after the exposure and remaining for a week or more until the surface layer of skin has peeled away.

Wear goggles, appropriate footwear, and follow all other standard laboratory precautions throughout the activity.

Procedure

1.Place a sheet of transparent plastic paper over the grid below. Place a small piece of copper in each space across the row which begins with Cu.

Zn(NO3)2 / Ag(NO3) / Cu(NO3)2 / Mg(NO3)2
Cu
Mg
Zn
  1. Place a small piece of Mg in each space across the row labeled Mg, and finally a small piece of Zn in each space across the row labeled Zn.
  2. Add only enough Zn(NO3)2 to cover each metal in the column labeled Zn(NO3)2. Use your lab notebook to record observations for each combination of materials. Observations should include a description of any changes which occur, rate of those changes, and any other relevant notes. Some of the reactions may be fast and easily detectable, while others will react only very slowly requiring patience and more careful observations. Some of the combinations will not react at all. The accuracy of your conclusions (and hence your grade) depend on making careful observations, and carefully discerning those combinations which react (but slowly)from those which do not react at all.
  3. Repeat step 3 for the other nitrate solutions, in the appropriately labeled columns. Again, record all observations.

Whiteboard: Each lab group should complete a whiteboard, summarizing their observations. From your results, draw the following conclusions:

Rank the reactivity of the metal nitrates from most reactive to least reactive.

Rank the reactivity of the pure metals, from most reactive to least reactive.

Explain why you chose the order of compounds which you chose.

Lab Report:

Type a formal lab report to summarize your methods, observations and conclusions. These typed reports must be completed independently. You may discuss your ideas with other members of the lab group, but written work must be entirely your own.

Lab report should include the following sections.

1Title

2Research question

3Summary of your methods. (briefly summarize, don’t copy, the procedure written here, including any changes in your own procedure, or errors you made and corrected during that procedure.)

4Data/observations. Provide a chart (like the one on the opposite side of this page) showing which materials reacted and which did not. Provide a detailed written description of your observations for those pairs of materials which chemically react.

5Conclusions (the most important section):

***Must include a set of balanced chemical equations describing the reactions which occurred.

***Arrange the metals Zn, Mg, Cu and Ag in the order of most reactive to least reactive. ( a metal is defined as “highly reactive” if it reacts easily with a large number of other materials). Provide a written explanation for why you have arranged the metals in the order you choose. If there is any pair of metals in this set which you are not able to rank, based on your data, describe an experiment(s) you might do (or repeat from this activity) to rank the reactivity of these two.

***Compare your results with those on pg 295 of your textbook. Do your experimental results agree with the table? Explain possible reasons for disagreement.