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wei1006
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Homework Statement
A solution of sodium hydroxide(NaOH) contains 1.70g of hydroxide (OH-) ions per dm^3. 20.0 cm^3 of the solution reacts with 25.00cm^3 of 0.0400 mol/dm^3 phosphoric acid(H3PO4). How many moles of sodium hydroxide reacts with 1 mol of phosphoric acid? What will be the chemical equation for the reaction?
Homework Equations
I have came up with an equation for the acid base reaction:
3NaOH + H3PO4 -----> Na3PO4 + 3H2O
The Attempt at a Solution
Actually I have no idea where to start for this question so I resorted to converting things I know into moles first but realized that I still have no idea how to attempt this question.
Moles of H3PO4
= (25.00/1000) x 0.0400
= 0.00100mol
Mole ratio: 3NaOH = H3PO4
Moles of NaOH
= 3 x 0.00100
= 0.00300mol
Concentration of NaOH in mol/dm^3
= 0.00300/ (20÷1000)
= 0.150 mol/dm^3
I am actually wondering what is the use of the given concentration of OH-
I have no idea how to attempt this kind of question. Please guide me along! Thank you.
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