# Titration Formula

A titration involves finding the unknown concentration of one solution by reacting it with a solution of known concentration. The solution of unknown concentration (the analyte) is usually placed in an Erlenmeyer flask, while the solution of known concentration (titrant) is placed in a burette. The titrant is added to the analyte until the endpoint is reached usually determined by a color change. Calculations are then performed to find the unknown concentration of the analyte. Titrations are typically performed on acid/base reactions but are not limited to them.

M_{acid} x V_{acid} = M_{base} x V_{base}

M_{acid } = Molarity of the acid

V_{acid } = Volume of the acid

M_{base } = Molarity of the base

V_{base} = Volume of the base

If the titrant and analyte have a 1:1 mole ratio, the equation above can be used to determine the unknown concentration, if the ratio is not 1:1 then a modified version should be used.

Titration Formula Questions:

1. Calculate the concentration of a 25 mL NaOH solution if 35 mL of 1.25 M HCl is needed to titrate to the equivalence point.

_{2}O

Answer:

In this equation the mole ratio of NaOH (base) and HCl (acid) is 1:1 as determined by the balanced chemical equation. The equivalence point is where the moles of titrant and analyte in the reaction are equal.

M_{acid} x V_{acid} = M_{base} x V_{base}

1.25 x 35 = M_{base} x 25

43.75 = M_{base} x 25

1.75 = M_{base}

2. Calculate the concentration of a 35.24 mL Ca(OH)_{2} solution if 28.35 mL of 1.21 M HNO_{3} is needed to titrate to the equivalence point.

Ca(OH)_{2} + 2HNO_{3} → Ca(NO3)_{2} + 2H_{2}O

Answer:

In this equation the mole ratio of acid (HNO_{3}) and base (Ca(OH)_{2}) is 2:1. In this case a modified version of the M_{acid} x V_{acid} = M_{base} x V_{base} equation is required.

2 x M_{acid} x V_{acid} = M_{base} x V_{base}

2 x 1.21 x 28.35 = M_{base} x 35.24

68.61 = M_{base} x 35.24

1.95 = M_{base}

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