Answer to Question #121647 in General Chemistry for Cass

Question

32.5 ml of H3PO4 requires 15.5 ml of 0.10 M Ca(OH)2. Find M for the H3PO4.

Answer 1

2H₃PO₄+3Ca(OH)₂=Ca₃(PO₄)₂+6H₂O

1.we first find the amount of Ca(OH)₂. To do this, we multiply the volume of Ca(OH)₂ by the concentration (liter): 0.0155litr*0.1mol/litr=0.00155mol

2.According to the above reaction, we find the amount of H₃PO₄: 0.00155*2/3=0.001mol

3.now we find the concentration of H₃PO₄. To do this, we divide the amount of H₃PO₄ by its volume:

0.001mol/0.0325litr=0.03077≈0.03mol/litr

Answer: 0.03mol/l