Q23E - Chemistry (OpenStax)

Question

When elemental iron corrodes it combines with oxygen in the air to ultimately form red brown iron(III) oxide which we call rust. 

(a) If a shiny iron nail with an initial mass of 23.2 g is weighed after being coated in a layer of rust, would you expect the mass to have increased, decreased, or remained the same? Explain.

 (b) If the mass of the iron nail increases to 24.1 g, what mass of oxygen combined with the iron?

Step-by-Step Solution

Answer

a.The mass is expected to be increased.

b.The mass of oxygen combined = \(0.9\,{\rm{g}}\)

Step 1. Analyzing if mass remains the same or increases or decreases

As the oxygen is combined with the iron nail, matter and mass combine.

So, the mass must increase.

Step 2. Finding the mass of oxygen combined

The initial mass of iron nail - \(23.2\,{\rm{g}}\)

Final mass after combining - \(24.1\,{\rm{g}}\)

Mass of oxygen combined = Final mass - Initial mass

                                              = \(24.1 - 23.2\)

                                               = \({\rm{0}}{\rm{.9}}\,{\rm{g}}\)