ShmoopTube

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Here's your shmoop du jour, brought to you by Calcium Chloride. Roads need it to grow

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up big and strong. Or... to keep from getting icy, or whatever.

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Which equation represents the heat of formation for Calcium Chloride?

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And here are your potential answers...

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Even if we have no idea about what the heat of formation is... let's think about it. FORMATION.

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We probably want the compound calcium chloride to be on the RIGHT side of the equation...

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since that's what's being FORMED. Which means we can immediately eliminate C.

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So now to learn what a heat of formation equation...is.

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A heat of formation equation shows the elements that make up the compound to be formed, in

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their standard state. It's important that they're in their standard

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state...which is basically whether they're solid, liquid, or gas at room temperature.

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Calcium is a solid at room temperature, and chlorine is a gas at room temperature...

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but a diatomic molecule...

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Meaning that it looks like Cl 2, not 2 Cl.

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These two molecules are in their standard states in option (D).

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D's our answer. We haven't had so much fun with formation

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since we got that lifetime supply of Play-doh...

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