posted by Kelly on .
show me step by step how to balance
2 H3(PO4)(aq) + 3 CaCl2(aq)
You can add the phases. You have it partly balanced but I am removing the 2 and 3 and start over.
First you write the products (and that isn't considered part of the balancing).
H3PO4(aq) + CaCl2(aq) ==> Ca3(PO4)2 + HCl
You do these by trial and error; basically that means you try a number and if that doesn't work you try another. However, you can help that hit ans miss method by asking yourself the right questions as you go along. Here we go. I look at the equation and immediately I see we have 3 Ca on the right. So let's place a 3 for Ca on the left.
H3PO4(aq) + 3CaCl2(aq) ==> Ca3(PO4)2 + HCl
Then I see on the right I need 2 PO4 so let's add a 2 for PO4 on the left.
2H3PO4(aq) +3CaCl2(aq) ==> Ca3(PO4)2 + HCl
So now I know the H3PO4 on the left and CaCl2 on the left as well as the Ca3(PO4)2 on the right are balanced. So I ask myself how many H and how many Cl do I have on the left? That's 6 so we make that balanced on the right with 6
2H3PO4(aq) + 3CaCl2(aq) ==> Ca3(PO4)2 + 6HCl