请用中英文对照的方式回答二氧化碳的化学式是什么，气体的性质。
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二氧化碳的化学式是 CO2。

**中文：**
- 化学式：CO2
- 性质：二氧化碳是一种无色无味的气体，密度比空气大，易溶于水，能够与水反应生成碳酸。它在常温常压下为气态，加压后可以变成液态或固态，固态二氧化碳俗称干冰。

**English：**
- Chemical Formula: CO2
- Properties: Carbon dioxide is a colorless and odorless gas with a density greater than air. It is soluble in water and reacts with water to form carbonic acid. Under normal temperature and pressure, it is in gaseous form; under pressure, it can be converted into liquid or solid form, with solid carbon dioxide commonly known as dry ice.
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