In an ionic equation, how do you know what pairs with what? For example:?

[land_of_ice]

molecular:
Pb(NO3)2 (aq) + 2 KI (aq) ----->2KNO3 (aq) + Pbl2 (s)
Ionic equation
Pb2+ (aq) + 2NO3- (aq) + 2 K (aq) + 2 I- (aq)----->2K+ (aq)+ 2NO3- (aq) + PbI2 (s)

I know why they break apart in the ionic part, its because ionic things aer broken up, but how would you know that they join together to form 2K+ (aq)+ 2NO3- (aq) + PbI2 (s) at the end? like in that order?

and one more question, how do you know that when certain things join together, that they form a solid, such as they way PbI2 (s) forms, because at first Pb was (aq), and I2 was (aq) also

 

[Borek]

how would you know that they join together to form 2K+ (aq)+ 2NO3- (aq) + PbI2 (s) at the end? like in that order?

Order doesn't matter, 2NO3- (aq) + PbI2 (s) + 2K+ (aq) is perfectly valid. Note that K⁺ and NO₃^- should be removed, as they are just spectators.

how do you know that when certain things join together, that they form a solid, such as they way PbI2 (s) forms, because at first Pb was (aq), and I2 was (aq) also

Do you know solubility rules?

 

[land_of_ice]

Order doesn't matter, 2NO3- (aq) + PbI2 (s) + 2K+ (aq) is perfectly valid. Note that K⁺ and NO₃^- should be removed, as they are just spectators.



Do you know solubility rules?

Can you explain how it uses the solubility rules? Because That's the part I don't understand. I know the solubility rules, just not how the solubility rules affect it and thanks so much for the help

 

[Borek]

You have four ions present: K⁺, Pb²⁺, I^-, NO₃^-. Basically you check all combinations that can create a salt (that means cation and anion) and you check if it is soluble or not.

In this particular case there are following combinations possible (do you see why?):
K⁺ & I^-
K⁺ & NO₃^-
Pb²⁺ & I^-
Pb²⁺ & NO₃^-

Try to apply solubility rules to find out which of the possible salts is insoluble and will precipitate.

 

[DeeNos]

I understand that in an ionic equation, the reactants (left side of the arrow) are written as their individual ions, while the products (right side of the arrow) are written as the resulting compound or solid. This is done based on the charges of the ions involved and their ability to combine to form a neutral compound.

In the given example, Pb2+ (aq) has a charge of +2 and NO3- (aq) has a charge of -1. In order for the charges to balance, two NO3- ions are needed to combine with one Pb2+ ion, resulting in Pb(NO3)2. Similarly, K+ (aq) has a charge of +1 and I- (aq) has a charge of -1, so two K+ ions are needed to combine with one I- ion, resulting in 2KI.

To determine the order of the products in the ionic equation, it is important to consider the solubility rules. In this case, both KNO3 and PbI2 are soluble in water, so they remain in their ionic form in the solution. Therefore, they are written in the same order as the reactants, with the cations (K+) first and the anions (NO3- and PbI2) last.

As for your question about how certain ions can combine to form a solid, this is determined by the solubility rules as well. In this case, PbI2 is insoluble in water, so when the Pb2+ and I- ions combine, they form a solid precipitate. This is a result of the strong attractive forces between the ions in the solid state.

Overall, the key to determining the pairs in an ionic equation is understanding the charges and solubility rules of the ions involved. By following these rules, we can accurately write the ionic equation to represent the chemical reactions taking place.