How do you balance this equation or is there no reaction??

Question

Consider the reactants in the partial equation given. Which choice is a product?

H3PO4 + Sr(OH)2 -->

a) no reaction
b) SrH3PO5
c) SrH5PO6
d)Sr2(PO4)2

Please explain how you get it also. I don't understand this one. Thanks!!

sorry...
choice d should be Sr3(PO4)2

I check the choices and it is correct as on my paper.

this question is really getting me a hard time.

Answer 1

There's two things you're being asked to recognize.
(1) what kind of reaction is this
(2) is it going to go forward?

Lets deal with them in order.

(1) What kind of reaction is it.

I find it very helpful personally to say the names of the molecules out loud.

Phosphoric Acid reacts with Strontium Hydroxide to form what?

Well, the first reactant is an acid, right? The second reactant is a metal hydroxide, like sodium hydroxide, so its a base. That makes this an acid-base neutralization. There's no redox chemistry going on here, so the bonds in the polyatomic anion, phosphate (PO4 (3-) ) are going to all remain intact.

Remember, an acid + base neutralization will always form water and a salt. In this case , your salt would be a combination of the non-hydrogen portions of the acid (PO4) and the metal.


(2) Will this reaction go forward?
Strontium hydroxide is moderately soluble in water. The phosphate salt very nonsoluble. That means that the product of the displacement will be taken "out" of the solution, driving the reaction towards formation of products.

*********NOTE**********
Many of your choices aren't charge-balanced molecules. This may help you tremendously. I think you may have a typo in your question.

*********NOTE 2*********
Once you fixed the choice (d) your typo was taken care of.

Answer 2

I would have said that the correct reaction is 2H3PO4 + 3Sr(OH)2 = Sr3(PO4)2 + 3H2O. Are you sure you've got choice d written correctly? If it was Sr2(PO4)2 it would be the right answer. How do I get this answer? Phosphoric acid and the base strontium hydroxide react to give the salt, strontium phosphate and water. The rest is just balancing to get the numbers of each type of atom to balance.

Answer 3

Probably c or a because there has to be at least 6 oxygen which rules out b and the hydrogen can't just disappear which rules out d.

Answer 4

1. AgNO3(aq) + NaI(aq) ---> AgI(s) + NaNO3(aq) 2. HCl(aq) + NaI(aq) ---> HI(aq) + NaCl(aq)