Does Strontium React with Water? Exploring the Chemical Behavior of StrontiumStrontium is a soft, silvery metal that belongs to the alkaline earth metal group in the periodic table. Similar to its group members like calcium and barium, strontium is known for its reactivity, particularly with water. But how does this reaction occur, and what are the products? This topic explains the reaction between strontium and water, explores its chemical properties, and looks at its practical implications.
What Is Strontium?
Strontium (symbol Sr, atomic number 38) is an alkaline earth metal located in Group 2 of the periodic table. It is relatively soft, with a metallic luster that tarnishes quickly in air. Naturally occurring strontium is found in minerals such as celestite and strontianite.
Like other Group 2 elements, strontium has two valence electrons, making it reactive, though less so than alkali metals like sodium or potassium.
Reactivity of Alkaline Earth Metals
The elements in Group 2 become more reactive as you move down the group. Beryllium is the least reactive, and barium is among the most reactive. Strontium sits below calcium and above barium, which means its reactivity is moderate but significant.
These metals react with water to form hydroxides and release hydrogen gas. The reactivity increases due to the decreasing ionization energy as atomic size increases.
Does Strontium React with Water?
Yes, strontium reacts with water, and it does so more vigorously than calcium but less violently than barium.
The chemical reaction
In this reaction
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Strontium metal combines with water.
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It forms strontium hydroxide, a slightly soluble base.
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Hydrogen gas is released as a byproduct.
This reaction is exothermic, meaning it releases heat. If enough metal is added at once, the hydrogen gas produced can ignite due to the heat of the reaction.
Observation of the Reaction
When strontium is placed in water, several visible signs appear
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Bubbles form on the metal surface (hydrogen gas).
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The metal dissolves slowly, with the solution becoming alkaline.
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A white precipitate may appear (strontium hydroxide).
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The water may warm slightly due to the exothermic nature of the reaction.
The reaction is less explosive than those involving alkali metals but should still be handled with care.
Factors Affecting the Reaction
Several conditions influence how strontium reacts with water
1. Surface Area
Finely powdered strontium reacts faster than a solid chunk because more of its surface is exposed to water.
2. Water Temperature
Warmer water increases the rate of reaction. In hot water, the reaction becomes more vigorous and produces hydrogen more rapidly.
3. Purity of the Metal
Pure strontium reacts more cleanly. Oxidized strontium (metal exposed to air) might have a dull layer that slows the reaction.
Strontium Hydroxide The Product
The main product of the reaction between strontium and water is strontium hydroxide, Sr(OH)₂. This is an alkaline compound that is
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Slightly soluble in water.
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Strong enough to turn red litmus paper blue.
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Commonly used in laboratories to study base reactions.
The solution created by this reaction is basic and may cause skin irritation due to its caustic nature.
Is the Reaction Dangerous?
Although the reaction is not highly explosive, it can still be hazardous under the wrong conditions. The release of hydrogen gas, a flammable substance, combined with the heat from the reaction, can pose a fire risk.
Proper safety precautions should be taken when experimenting with strontium
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Use safety goggles and gloves.
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Conduct the experiment in a well-ventilated area or under a fume hood.
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Keep sources of ignition away from the reaction area.
Comparison with Other Group 2 Elements
Understanding how strontium reacts compared to other alkaline earth metals helps illustrate its behavior
| Element | Reaction with Water | Notes |
|---|---|---|
| Beryllium | No reaction | Forms a passivating oxide layer |
| Magnesium | Very slow reaction | Slight fizzing with hot water |
| Calcium | Moderate reaction | Bubbles and dissolves slowly |
| Strontium | Vigorous reaction | Forms Sr(OH)₂ and H₂ |
| Barium | Rapid reaction | Highly reactive, even in cold water |
This comparison shows that strontium is quite reactive, making it a good example of a mid-group alkaline earth metal.
Real-World Applications of Strontium
Although the water reaction is mainly of academic interest, strontium has several practical uses
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Strontium salts, such as strontium nitrate, are used in fireworks to produce red colors.
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Strontium-90, a radioactive isotope, is used in nuclear medicine and as a heat source in satellites.
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Strontium compounds are studied for use in dental and bone treatments.
These applications rely on various strontium compounds rather than the metal itself, but understanding its reactivity helps in handling and preparing the element.
Summary
Strontium is a reactive metal that does react with water to form strontium hydroxide and hydrogen gas. This reaction is exothermic and produces visible bubbling and a basic solution. While not explosive, the reaction can become hazardous if not handled properly.
As a member of the alkaline earth metal group, strontium demonstrates the increasing reactivity trend down the group. It sits between calcium and barium in both reactivity and atomic structure.
Understanding the reaction of strontium with water provides valuable insights into chemical behavior, trends in the periodic table, and practical considerations in both laboratory and industrial settings.