[ether]

Hello Chemical Forums! I'm the new kid on the block so if my etiquette is not up to par just inform me how I might fix it and I'll do my best to do so.

Maybe I've just been staring at this problem for too long, but I've got myself twisted around on a chemical reaction problem.

The original problem: "Mix 3 drops of 0.1 M Pb(NO₃)₂ with 3 drops of 0.1. M KI."

Which lead me to the formula equation: Pb(NO₃)₂ + 2KI = PbI₂ + 2KNO₃

Which leads me to the total ionic equation: Pb²⁺ (s) + (NO₃)^-₂ (aq) + 2K⁺I^- (s) = PbI₂ (s) +2KNO₃ (aq)

Which, lastly, would give me the same equation for my net ionic equation since nothing is exactly the same on both sides of the equation.

Am I simply separating my ionic compounds too far? (For example, giving me Pb(NO₃)₂ (aq) + 2KI (aq) = PbI₂ + 2KNO₃ (aq) for my total ionic equation?) Or am I even vaguely on the right track?

Thanks in advance!

[Dan]

You're on the right track, but your state symbols are not good and you need to separate some more salts - remember lead nitrate is soluble in water, so is potassium iodide and potassium nitrate.

[ether]

Thanks, Dan!

So you're saying it should look something more like this:

Total Ionic Equation: Pb²⁺ (aq) + 2NO₃^- (aq) + 2K⁺ (aq) + I^- (aq) = PbI₂ (s) +2K⁺ (aq) + 2NO₃^- (aq)

Net ionic equation: Pb²⁺ (aq) + I^- (aq) = PbI₂ (s)

[Dan]

Almost - your iodides aren't balanced

[ether]

Whoops!

Total Ionic Equation: Pb²⁺ (aq) + 2NO₃- (aq) + 2K⁺ (aq) + I^- (aq) = PbI₂ (s) + 2K⁺ (aq) + 2NO₃^- (aq)

Net ionic equation: Pb2⁺ (aq) +2I^- (aq) = PbI₂ (s)

Thanks so much!


I also ran into a few more questions.

Original problem: "Mix 3 drops of 0.1 M Fe(NO₃)₃ with 3 drops of 0.1 M KOH."

Formula equation: Fe(NO₃)₃ + KOH = FeOH + K(NO₃)₃

Total Ionic Equation: Fe³⁺ (aq) + 3NO^- (aq) + KOH (aq) = Fe³⁺ (aq) + OH^- (s) + K⁺ (aq) + 3 NO₃ (aq)

Net Ionic Equation: KOH (aq) = OH^- (s)

Potassium hydroxide needs to be together for it to be soluble, correct? I know it's one of the exceptions to the rule of hydroxides being insoluble.


Original question: "Mix 3 drops of 0.1 M Ca(NO₃)₂ with 3 drops of 0.1 M Na₃PO₄."

Formula equation: Ca(No₃)₂ + Na₃PO₄ = CaPO₄ + Na₃(NO₃)₂

Total Ionic Equation: Ca²⁺ (aq) +2NO₃ (aq) + Na₃PO₄ (aq) = Ca²⁺ (aq) + PO₄ (s) + Na₃ (aq) + 2 NO₃ (aq)

Net Ionic Equation: Na₃PO₄ = PO₄ (s)

Am I way off on this one?

And just to make sure I've got this straight: anything insoluble doesn't break apart or have its ions shown, right?


Original question: "To a test tube containing 3mL of 6 M HCL, add a piece of mossy zinc. If a gas evolves, point the test tube away from other and quickly insert a lighted splint into the mouth of the test tube. Balance the equations for both reactions.

Balanced equation (reaction 1): HCl + Zn = H + ZnCl

Reaction type: Single replacement reaction.

Would the second equation be the same since, at room temperature, hydrogen chloride is already a gas?


And last one for now.

Original question: "To a test tube containing 3 mL of 3% H_2O2 (hydrogen peroxide), add a very small amount (About 1/3 spatula)of the catalyst MnO₂."

Balanced equation: H₂O₂ + MnO₂ = H₂O₂ + MnO₂.

Would this still be a double replacement reaction even though it does not appear to produce different compounds?


Thanks again!

[Dan]

Total Ionic Equation: Pb²⁺ (aq) + 2NO₃- (aq) + 2K⁺ (aq) + I^- (aq) = PbI₂ (s) + 2K⁺ (aq) + 2NO₃^- (aq)

Iodide still not balanced.

Net ionic equation: Pb2⁺ (aq) +2I^- (aq) = PbI₂ (s)

Fine

Formula equation: Fe(NO₃)₃ + KOH = FeOH + K(NO₃)₃

No, FeOH does not exist, and nor does K(NO₃)₃. This is not a redox reaction, the oxidation state of iron will remain unchanged. What are the charges on iron, potassium, nitrate and hydroxide? Keep track of them and combine ions to give neutral compounds.

Potassium hydroxide needs to be together for it to be soluble, correct? I know it's one of the exceptions to the rule of hydroxides being insoluble.

No. KOH is soluble in water, which means it dissociates in water. All solids are neutral, you cannot have a lump of hydroxide - there has to be a counterion. So you will have ^-OH(aq) on the left hand side, and it will combine with something else to form an insoluble compound.

Formula equation: Ca(No₃)₂ + Na₃PO₄ = CaPO₄ + Na₃(NO₃)₂

No. What are the charges for the ions calcium, sodium, nitrate and phosphate? Note charges and recombine ions to make neutral compounds.

Balanced equation (reaction 1): HCl + Zn = H + ZnCl

No. What are the stable oxidation states of Zinc? What form does elemental hydrogen exist in?

Balanced equation: H₂O₂ + MnO₂ = H₂O₂ + MnO₂.

No. The equation is not balanced and you are missing a product. Going hydrogen peroxide to water is a reduction - if something is reduced, something else must be oxidised...