Question detail
What happens when calcium reacts with water? Write the balanced equation for this reaction.
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
Question
Type
exam_style
Style
Topic
Group 2, the alkaline earth metals
Question
What happens when calcium reacts with water? Write the balanced equation for this reaction.
Answer
When calcium reacts with water, it produces calcium hydroxide (Ca(OH)2) and hydrogen gas (H2). The balanced equation is: Ca + 2H2O → Ca(OH)2 + H2.
Explanation
This answer is strong as it includes both the products formed and the balanced chemical equation, showing a clear understanding of the reaction between a Group 2 metal and water. The question assesses knowledge of Group 2 reactivity.
Common mistake
Misunderstanding Group 2 Metal Reactivity
Students often confuse the reactivity of Group 2 metals with non-metals, thinking they react similarly with oxygen, water, and acids.
To clarify, remember that Group 2 metals react with oxygen to form metal oxides, with water to produce hydroxides and hydrogen gas, and with acids to yield salts and hydrogen gas. For example, the reaction of magnesium with water can be represented as: 1. **Formula**: Mg + 2H2O → Mg(OH)2 + H2 2. **Substitution**: Here, magnesium reacts with water to form magnesium hydroxide and hydrogen gas. 3. **Working**: The magnesium displaces hydrogen from water, resulting in the formation of magnesium hydroxide. 4. **Answer**: The products are magnesium hydroxide (Mg(OH)2) and hydrogen gas (H2). 5. **Units/Conclusion**: This shows that Group 2 metals react with water to produce hydroxides, which is a key characteristic of their reactivity.
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