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Chemical Reactions Unit Test 1 of 181 of 18 Items Question Which of the following equations shows a chemical change? Responses C2H5OH(l)→C2H5OH(g) no response given H2O(s)→H2O(g) no response given C3H8+5O2→3CO2+4H2O no response given NH3(g)→NH3(l) no response given Skip to navigation

1 answer

In the context of chemical reactions, a chemical change involves the transformation of substances into different substances with new chemical formulas. Let's analyze the options provided:

  1. C2H5OH(l) → C2H5OH(g): This is a physical change (liquid to gas), not a chemical change.

  2. H2O(s) → H2O(g): This is also a physical change (solid to gas), not a chemical change.

  3. C3H8 + 5O2 → 3CO2 + 4H2O: This represents the combustion of propane (C3H8) and is a chemical change because the reactants are transformed into new products (carbon dioxide and water).

  4. NH3(g) → NH3(l): This is a physical change (gas to liquid), not a chemical change.

Based on this analysis, the equation that shows a chemical change is:

C3H8 + 5O2 → 3CO2 + 4H2O.