what is the molarity

Question

Potassium hydrogen phthalate is a solid, monoprotic acid frequently used in the laboratory as a primary standard. It has the unwieldy formula of KHC₈H₄O₄. This is often written in shorthand notation as KHP.

If 23.09 mL of a sodium hydroxide solution are needed to neutralize 2.515 grams of KHP, what is the concentration (mol/L) of the sodium hydroxide solution?

Answer 1

KHP is KHC₈H₄O₄

Balanced equation:

KHC₈H₄O₄+NaOH→H₂O+NaKC₈H₄O₄

molar mass KHP

For KHP: 204.22 g KHC₈H₄O₄= 1 mol KHC₈H₄O₄

Convert g KHP to mol KHP with molar mass:

2.515g / (204.22 g/mol)=0.0123151503 mol KHP

convert mol KHP to mol NaOH with coefficients:

0.0123151503 mol KHP (1mol NaOH / 1 mol KHP)=0.0123151503 mol NaOH

Use moles NaOH and volume to find molarity:

Molarity=moles/L

moles=0.0123151503 moles NaOH

23.09mL (1L/1000mL)=0.02309L

M=0.0123151503mol/0.02309L

M=0.533354278909 M

sig figs: 0.5333 M NaOH(aq)