alleryStart learning →Why may the subscripts in a formula not be altered when balancing an equation?
AAltering them changes the substance itself
BAltering them changes only the state given
CAltering them changes the speed of reaction
DAltering them changes the arrow direction
Answer & Solution
Correct answer: A. Altering them changes the substance itself
1. Subscripts inside a formula fix how many atoms of each element make up one unit of the substance.
2. Changing H2O to H2O2 does balance oxygen, but the substance is then hydrogen peroxide, not water.
3. So subscripts define identity and must stay fixed.
4. Only coefficients, which sit outside the formula, may be changed to achieve balance.
5. State symbols and reaction rate are separate matters and are not set by subscripts.
_Source: OpenStax Chemistry (CC BY 4.0), Ch 4 "Stoichiometry of Chemical Reactions", section 4.1 Writing and Balancing Chemical Equations_
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