Concord High School Chemistry

Balancing Equations Online Help

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Practice Problems Here:

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Practice Problem #2:

Rb3AsO4  +  BaCr2O7 –>

Answer to Practice Problem #2:

1. Identify the type of reaction.

            Double-replacement reaction.

Rb+ is a cation, so it will switch with Ba2+ (also a cation).

Rb3AsO4  +  BaCr2O7 –>

2. Write out the products of the chemical reaction.

            Switch the cations, since this is single-replacement:

Rb3AsO4  +  BaCr2O7 –> Rb Cr2O7   +   Ba AsO4

            Then write the formulas of the products based on their charges.

            Rb = +1, Cr2O7 = -2, so the formula is Rb2Cr2O7.

            Ba = +2, AsO4= -3, so the formula is Ba3(AsO4)2.

Rb3AsO4  +  BaCr2O7 –> Rb2Cr2O +  Ba3(AsO4)2

3. Balance the equation.

Rb3AsO4  +  BaCr2O7 –> Rb2Cr2O +  Ba3(AsO4)2

Balance this equation by putting the coefficients in front of the compounds.

            Last, double check that all numbers of atoms of each element is equal.

Answer to Problem: 2Rb3AsO4  +  3BaCr2O7 –> 3Rb2Cr2O +  Ba3(AsO4)2


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