Question

Dr Bob
Is it true that only TWO molecules of water are required to balance the equation for the reaction of HCL with Calcium Hydroxide.(calcium chloride is the other product....why???
Thanks andy

Answer 1

HCl + Ca(OH)2 ==> CaCl2 + H2O

I start by seeing 2 Cl on the right. I fix that with a 2HCl
2HCl + Ca(OH)2 --> CaCl2 + H2O

So Ca and Cl now balance. That leaves only H and O. I usually count what I have on the left (since the 2 for HCl and 1 for Ca(OH)2 seem to be ok.) I see 4 H atoms on the left (2 from HCl and 2 from Ca(OH)2. So I add a 2 for H2O on the right.
2HCl + Ca(OH)2 ==> CaCl2 + 2H2O.

So yes, water requires a 2. WHY? Because everything balances with 2H2O. Stick any other number there and it won't balance.

Answer 2

thanks so much....andy