## daniceko 2 years ago Help? ill give medal :) Show your work Write a balanced net ionic equation for the following reaction. H3PO4(aq) + Ca(OH)2(aq) Ca3(PO4)2(aq) + H2O(l)

1. daniceko

@kelly226 can you help

2. BluFoot

I'll help :) So you want to try and have the same number of each element on each side. This is a pretty tricky one. It looks like you have twice as many P on the right as on the left side. So try adding a 2 in front of H3PO4 on the left side as a starter!

3. daniceko

This is really confussing for me so now i have 2 H3PO4(aq) + Ca(OH)2(aq) Ca3(PO4)2(aq) + H2O(l)

4. BluFoot

If you're REALLY confused, you should start with easier questions, this one's pretty tricky. So good now try the same thing with Ca. You have 3 Ca on the right and 1 on the left.

5. daniceko

So would i put the 2 in front of the Ca like this? 2 H3PO4(aq) + 2Ca(OH)2(aq) Ca3(PO4)2(aq) + H2O(l) and btw there is no easier questions on the packet this is the only one like this

6. BluFoot

3* :) not 2 this time

7. BluFoot

So: 2 H3PO4(aq) + 3Ca(OH)2(aq) -> Ca3(PO4)2(aq) + H2O(l) Now count your H's and O's on both sides and see if they're the same.

8. daniceko

I think the Os are the same but are the Hs the same

9. BluFoot

So do it carefully. 2H3PO4 has 2*3 = 6 H and 2*4=8 O 3Ca(OH)2 has 3*2 = 6 H and 3*2 = 6 O So the left side has 14 O and 12 H Ca3(PO4)2 has 4*2 = 8 O H2O has 2H and 1 O So the right side has 9 O and 2 H So the right side has way less Os and Hs. Can you figure out how to balance that out?

10. daniceko

In order to balance it out i have to add 5 o and 10 H some how right

11. BluFoot

Exactly! How can you get that?

12. BluFoot

Hint: use H2O

13. daniceko

could i add 5 to the H2O n the right end

14. BluFoot

Yes :) When you're adding 5 make sure you're adding 5 to 1. So the final thing should be 6H2O.

15. daniceko

Yay :) so now I have 2 H3PO4(aq) + 3Ca(OH)2(aq) -> Ca3(PO4)2(aq) + 6H2O

16. BluFoot

That's the final answer! You can check it by counting everything of course. I started with P and Ca because they're only present in one of the compounds on each side, so they're easier to balance. Try to do the same when working on other problems.

17. daniceko

Thank You so much your a genious :) But what about earlier when they were un equal bc of 5 o and 10 H I added the 5 ut what about the 10

18. BluFoot

Kinda hard to understand you there :P But you added 5 H2O. So you added 5*2=10 H and 5 O. Exactly what you needed.

19. daniceko

Ok I understand now thank you so much for your help

20. BluFoot

You are very welcome

21. BluFoot

That's what he wrote. Except an arrow instead of the = sign. It's a reaction, not an equation.

22. daniceko

wait is there (aq) in the final equation?

23. daniceko

@BluFoot is there (aq) in the final equation?

24. BluFoot

The states don't change when you balance the equation. So 2 H3PO4(aq) + 3Ca(OH)2(aq) -> Ca3(PO4)2(aq) + 6H2O (l) is correct

25. daniceko

oh ok thanks