Testing a nickel band material

Jul 25, 2019

I recently purchased a “pure nickel” band for use in building a battery pack.

Store listing for nickel band
Store listing for nickel band

However, from various forum posts, I’ve learned that it’s unlikely that these strips are really made up of what they claim to be made up of, so I decided to test the product.

By weight

When measured on a scale, the product I received was .

The volume, as calculated from the vendor’s measurements, should be .

Nickel’s density is .

So clearly something is off. I either received too little product, or it was not actually made of nickel.

Steel has a density of to .

The low end of this range ends up being exactly what my band weighs, a point of evidence towards my band being made up mostly of steel.

Flame test

One way to find out what it’s actually made up of is to conduct a flame test.

Yellow/orange flame from nickel strip
Yellow/orange flame from nickel strip

The flame isn’t silver-white, so it’s clearly not coming from nickel. It’s orange, which indicates either iron or sodium.

Potential contamination

Sodium is a common component or contaminant in many compounds and its spectrum tends to dominate over others[1]

At first, I didn’t realize that sodium contamination could be a problem. After careful reading though, I decided to try cleaning my strip in hydrochloric acid before applying the flame. This mimics the procedure used when placing flame test samples on a platinum wire:

Samples are usually held on a platinum wire cleaned repeatedly with hydrochloric acid[1]

After doing this, the results were very different:

Orange flame from a cleaned nickel strip
Orange flame from a cleaned nickel strip

This flame is much more clearly orange, and has no yellow tint to it, like it did before. The orange here clearly indicates the presence of iron.

However, when I then touched the band with my fingers and applied the flame again, I’d get an orange flame. This shows that the tiny amount of sodium contamination from my fingers has a drastic result on the color of the flame–and it’s a neat, intuitive, way of seeing why sodium was chosen for sodium-vapor lamps.

Conclusion

Both the orange glow from the acid-cleaned band and the density of the band indicate that this product is not made of nickel.