Question

# [Make sure to do both problems to get a thumbs up] 1. What volume (in mL)...

[Make sure to do both problems to get a thumbs up]

1. What volume (in mL) of 0.08970 M HNO3 is required to react completely with 0.2391 g of potassium hydrogen phosphate?

2 HNO3(aq) + K2HPO4(aq) → H2PO4(aq) + 2 KNO3(aq)

2. Potassium acid phthalate, KHC8H4O4, or KHP, is used in many laboratories, including general chemistry laboratories, to standardize solutions of base. KHP is one of only a few stable solid acids that can be dried by warming and weighed. A 0.3574 g sample of KHC8H4O4 reacts with 34.79 mL of a NaOH solution in a titration. What is the molar concentration of the NaOH?

KHC8H4O4(aq) + NaOH(aq) → KNaC8H4O4(aq) + H2O(l)

1)

molar mass of K2HPO4 = 174.2 g/mol

number of moles of K2H4PO4 = mass/molar mass

= 0.2391 / 174.2

=1.373*10^-3 mol

from given reaction,

2 moles of HNO3 reacts with 1 mol ofK2H4PO4

so mol of HNO3 needed = 1.373*10^-3 * 2 =2.746*10^-3 mol

mol of HNO3 = M (HNO3)*V(HNO3)

2.746*10^-3 = 0.08970 * V

V = 0.0306 L

= 30.6 mL

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