Question Video: Identifying the Element That Will Not React with Hot Water Vapor Science

Video Transcript

Which of the following elements will not react when exposed to hot water vapor? (A) Zinc, (B) potassium, (C) calcium, (D) copper, (E) iron.

To answer this question, we need to determine which of the given elements will not react with hot water vapor.

All of the given elements are metals. Some metals are more reactive than others. The chemical activity series is a list that shows how active elements are when compared to others. We can use this list to help us determine which elements will react with water.

Here we have a list of the names and chemical symbols of some metal elements and the nonmetal element hydrogen. Elements that are higher up on the series are more active than elements that are lower down. Elements that are above the element hydrogen can react with water. But we need to know which elements will not react with hot water vapor. So let’s take a look at the elements in the series more closely.

Metals that are higher on the series react faster and more strongly with water. For example, potassium and sodium react very quickly and intensely with cold water. If we added a piece of potassium to water, we would observe a lot of bubbling and may see flames on the surface of the water. The bubbling happens because hydrogen gas is being produced during the chemical reaction. The reaction also releases a lot of heat. Because of this, some of the hydrogen gas can ignite. This is one reason why we see flames.

Calcium and magnesium are below sodium and potassium in the series. These two metals react more slowly with cold water. They also react less strongly. If we added these metals to water, we would still see bubbling as the hydrogen gas is produced. But we would not see any flames.

Zinc and iron are even less active than calcium and magnesium. These two metals do not react with cold water. So does this mean they do not react with water vapor? These metals are active enough to react with water vapor, but only if the water vapor is very hot.

To do this, we could strongly heat a test tube that contains cotton wool soaked with water and zinc metal. The water is converted to steam and reacts with zinc. Yellowish zinc oxide and hydrogen gas form, which escapes the tube.

The elements copper and silver are less active than hydrogen. They do not react with water at all. This means they will not react with liquid water or water vapor.

Now we see that answer choices (A), (B), (C), and (E) are all incorrect. These four metals are more active than hydrogen and can react with water. Copper is the only element in the answer choices that is not active enough to react with hot water vapor. So the correct answer is answer choice (D), copper.