Understanding the Reaction Between Sodium Phosphate and Cobalt II Chloride: Products and Balanced Equation

When sodium phosphate (Na?PO?) reacts with cobalt(II) chloride (CoCl?), a double displacement reaction occurs, resulting in the formation of cobalt(II) phosphate (Co?PO??) and sodium chloride (NaCl). This article delves into the details of this reaction, including the products and the balanced chemical equation.

The Chemical Reaction

When sodium phosphate and cobalt(II) chloride are mixed, the sodium ions (Na?) and cobalt ions (Co2?) exchange places with the phosphate ions (PO?3?) and chloride ions (Cl?). The expected products are cobalt(II) phosphate (Co?PO??) and sodium chloride (NaCl).

The Balanced Equation

To accurately represent the reaction, we start with an unbalanced equation:

Na?PO? CoCl? → Co?PO?? NaCl

Next, we balance the equation to ensure the number of atoms of each element is conserved on both sides. Here’s the step-by-step balancing process:

Consider the cobalt phosphate (Co?PO??) as a whole compound: There are 3 cobalt ions in Co?PO??, so we need 3 moles of CoCl? to balance the cobalt ions. Each mole of CoCl? contributes 2 chloride ions (Cl?), and we need 6 chloride ions (2 NaCl molecules) to balance the equation. We need 2 moles of sodium phosphate (Na?PO?) to provide the 6 sodium ions (2 NaCl molecules).

After balancing the equation, we have:

2 Na?PO? 3 CoCl? → 6 NaCl Co?PO??

This balanced equation indicates that two moles of sodium phosphate react with three moles of cobalt(II) chloride to produce six moles of sodium chloride and one mole of cobalt(II) phosphate.

This is a Precipitation Reaction

This reaction is typically carried out in solution, where the reactants (Na?PO? and CoCl?) are initially soluble, as is the product sodium chloride (NaCl). However, cobalt(II) phosphate (Co?PO??) is insoluble in water, leading to a precipitate.

Understanding the Reaction Mechanism

To fully understand the reaction, it's helpful to look at the ionic components involved. The oxidation numbers for each ion are as follows:

Na?: 1 PO?3?: -3 Co2?: 2 Cl?: -1

In this reaction, oxidation numbers remain the same on both sides of the equation, indicating a double displacement reaction:

2 Na?PO? 3 CoCl? → 6 NaCl Co?PO??

Using the balancing by inspection method, we ensure that the number of each atom remains consistent on both sides of the equation. We also check the equation by counting the constituent atoms and polyatomic ions, treating PO? as an entity rather than breaking it down into phosphate and oxygen atoms.

Conclusion

To summarize, sodium phosphate (Na?PO?) and cobalt(II) chloride (CoCl?) undergo a double displacement reaction to produce cobalt(II) phosphate (Co?PO??) and sodium chloride (NaCl), as represented in the balanced equation: 2 Na?PO? 3 CoCl? → 6 NaCl Co?PO??.

This reaction not only highlights the principles of balancing chemical equations but also demonstrates the mechanism of a precipitation reaction in aqueous solutions.