Answer:
Explanation:
How many cm of a solution of 0.100 mol dm NaOH are required to completely neutralize 25.0 cm of 0.250 mol dm H3PO4?.
a) Write a balanced equation for the reaction NaOH to neutralize (4 marks
?. ) 25.0 cm of 0.250 mol dm H3PO4
H3PO4 + 3NaOH----------> Na3PO4 +3 H2O
b) How many moles of H3PO4 need to be neutralized? (1 marks)
25.0 cm3 of 0.250 mol dm3 H3PO4: 1 liter has 0.25 moles. 100 ml has 0.025 moles 25 ml has o.025/4 molea or 0.00625 moles)
c How many moles of NaOH are needed to neutralize the H3PO4? (1 marks)
for every moles of H3PO4, WE NEED 3 MOLES OF NaOH. FOR 0.00625 MOLES WE NEED 3X 0.00625 =0.01875 MOLES OF NaOH
d) How many cm3 of 0.100 mol /l NaOH contain the moles in question 5(©) above? (1 marks)
1 L CONTAINS 0.100 Moles
100 ml contains 0.010Moles
we need 187.5 ml since (187.5 X 0.100)/1000=0.01875
