Home > Community > Calcium reacts with oxygen to form calcium oxide. What is a balanced chemical equation for the reaction?
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+ Chemical reactions
+ Calcium carbonate
+ Oxygen
+ Chemistry
+ Oxides
+ Calcium
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Mary Lawlor

Calcium reacts with oxygen to form calcium oxide. What is a balanced chemical equation for the reaction?

Byron Varvarigos  Follow

Calcium hydroxide thermal decomposition is the name for this reaction.

Ca(OH)[math]_2[/math] → CaO + H[math]_2[/math]O

56 grams of CaO is a mole and 18 grams of water is a mole so you started with a mole of calcium hydroxide.

Dynamic Periodic Table

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Blake Bartmus  Follow

Required equation for the above is given as

2Ca+ O2-->2CaO

Oxidation state of Ca:- 0

Oxidation state of O2:0

Oxidation state of Ca in CaO:-+2

Oxidation state of oxygen in CaO:- -2

Calcium gets oxidised from 0 oxidation state to an oxidation state of +2

Hence oxygen is the oxidant(or the oxidizing agent)in the given question

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Derek Williams  Follow

Well, we could write…

[math]Ca(s) + dfrac{1}{2}O_{2}(g) longrightarrow Ca^{2+}O^{2-}(s)[/math]

Calcium oxide is the anhydride of calcium hydroxide….

[math]Ca^{2+}O^{2-}(s)+H_{2}O(l) longrightarrow Ca^{2+}(^{-}OH)_{2}(aq)[/math]

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David Miller  Follow

No, it does not. Actually, both calcium and hydrogen in Ca(OH)2 are at the highest oxidation states (+2 and +1, respectively) allowed for them. Yet Ca(OH)2 readily reacts with atmospheric CO2 to give CaCO3.

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Dawn Leeper  Follow

It is possible to burn calcium in pure oxygen:

2Ca + O2(g) = 2CaO

Change in Free Energy: ΔG(1000C) = -1000.9kJ (negative, so the reaction runs)

Change in Enthalpy: ΔH(1000C) = -1288.6kJ (negative, so the reaction is exothermic)

This reaction produces calcium oxide but no hydrogen.

So perhaps you meant the reaction of calcium with water:

Ca + H2O(l) = Ca(OH)2 + H2(g)

Change in Free Energy: ΔG(20C) = -423.8kJ (negative, so the reaction runs)

Change in Enthalpy: ΔH(20C) = -413.9kJ (negative, so the reaction is exothermic)

And this reaction does produce hydrogen and calcium hydroxide, but no calcium oxide.

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David B?ckman  Follow

You are kidding right? Calcium oxide is CaO, so you need one calcium and one oxygen.

2Ca(s) + O2(g) → 2CaO(s)

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Chux777  Follow

CaO + H2O =Ca(OH)2

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Nigel West  Follow

First, CaO will react with water to for Ca(OH)2. From there, it is like any other acid/base reaction. If the Ca2+ ion is solvent with the acid anion, then both will remain in solution while the hydroxide and hydronium ions combine to form water in accordance with their pKa.

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Bob Lawson  Follow

I guess you are taking about the thermal decomposition reaction of calcium carbonate

[math]CaCO_3 = CaO + CO_2 [/math]

At about 825°C if I remember correctly, calcium carbonate breaks down to calcium oxide and carbon dioxide (the products) the calcium carbonate is the only “reactant”

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Charles Thomas  Follow

CaO + H2O -> Ca(OH)2 + Heat (highly exothermic reaction)

When calcium oxide reacts with water, Calcium Hydroxide (slaked lime) is formed. Calcium Hydroxide is an Alkali.

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Charles Brown  Follow

Calcium oxide reacts with water to form calcium hydroxide. The reaction is exothermic.

CaO(s) + H₂O(ℓ) → Ca(OH)₂(s/aq) …… ΔH < 0

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