Corrosion

Adapted from: Lawson, Anton, & Birk, James. Chemistry - A Learning Cycle Approach. 1991. Arizona State University.
Unit 15 Investigation

Why do Metals Corrode?

Introduction

As Head Chemist at Continental Container Corporation, you have just received a huge order from Allied Chemical to manufacture one thousand containers. Allied Chemical needs the containers for storage of five kinds of aqueous nitrate solutions. The aqueous nitrates are copper (II) nitrate, lead (II) nitrate, zinc nitrate, magnesium nitrate, and silver nitrate.

You can not manufacture the containers from glass due to possible breakage. Nor will plastic containers do because plastic tends to harden over time and also may shatter. This leaves metal. Unfortunately, many metals get eaten away (corrode), when they come in contact with aqueous nitrates.

Company documents indicate that copper, lead, zinc, and magnesium metals may work for aqueous nitrate storage. But the documents do not indicate which of the metals will work best for the particular liquid nitrates that Allied needs to store. Therefore, your job is to conduct experiments to determine which of these metals will avoid corrosion and work best.

Objectives

1. To determine which of the four metals will make appropriate containers for each of the five aqueous nitrates.

2. To propose a hypothesis that explains why metals corrode.

Materials used in the video

Strips of the following metals:

Copper, Cu
Lead, Pb
Zinc, Zn
Magnesium, Mg

The following solutions:

Copper (II) nitrate, Cu(NO3)2
Lead (II) nitrate, Pb(NO3)2
Zinc nitrate Zn(NO3)2
Magnesium nitrate, Mg(NO3)2
Silver nitrate, AgNO3

Fine sandpaper
Goggles
Lab apron

Directions: Fill in your observations from the videos and pictures in the table below.

DATA TABLE

Aqueous Nitrates

Metals
Mg(NO3)2
Zn(NO3)2
Cu(NO3)2
Pb(NO3)2
AgNO3

Mg

Zn

Cu

Pb