Question

Min is asked to balance the equation below.

Answer 1

It is incorrect, because the identity of the original product has changed. Ca3(OH)2 does not exist! It is no longer calcium hydroxide. To balance an equation, you must manipulate the coefficients, a.k.a. the big numbers that go before reactants or products. Subscripts, the little numbers inside the reactants or products, cannot be changed without completely changing the substance.

Answer 2

Ca3P2 + H2O → Ca(OH)2 + PH3

Min’s result: Ca3P2 + H2O → Ca3(OH)2 + PH3

Which best describes Min’s method for balancing the chemical equation?

It is correct, because now there are three Ca atoms on each side of the equation.

It is incorrect, because the identity of the original product has changed.

It is correct, because Ca3(OH)2 creates a more stable compound.

It is incorrect, because the subscript “2” should be added instead.

Answer: B