Vitamin C is ascorbic acid, HC6 H7 O6, which can be titrated with a strong base. HC6 H7 O6(aq)+N

step 1 So let's do a special type of acid -based reaction via titration. Titration is a very accurate w

Vitamin C is ascorbic acid, HC6 H7 O6, which can be titrated...

Vitamin $\mathrm{C}$ is ascorbic acid, $\mathrm{HC}_{6} \mathrm{H}_{7} \mathrm{O}_{6},$ which can be titrated with a strong base. $\mathrm{HC}_{6} \mathrm{H}_{7} \mathrm{O}_{6}(\mathrm{aq})+\mathrm{NaOH}(\mathrm{aq}) \longrightarrow \mathrm{NaC}_{6} \mathrm{H}_{7} \mathrm{O}_{6}(\mathrm{aq})+\mathrm{H}_{2} \mathrm{O}(\ell)$ A student dissolved a $500.0-\mathrm{mg}$ vitamin $\mathrm{C}$ tablet in $200.0 \mathrm{~mL}$ water and then titrated it with 0.1250 -M $\mathrm{NaOH}$. It required $21.30 \mathrm{~mL}$ of the base to reach the equivalence point. Calculate the mass percentage of the tablet that is impurity.

Vitamin $\mathrm{C}$ is ascorbic acid, $\mathrm{HC}_{6} \mathrm{H}_{7} \mathrm{O}_{6},$ which can be titrated with a strong base.
$\mathrm{HC}_{6} \mathrm{H}_{7} \mathrm{O}_{6}(\mathrm{aq})+\mathrm{NaOH}(\mathrm{aq}) \longrightarrow \mathrm{NaC}_{6} \mathrm{H}_{7} \mathrm{O}_{6}(\mathrm{aq})+\mathrm{H}_{2} \mathrm{O}(\ell)$
A student dissolved a $500.0-\mathrm{mg}$ vitamin $\mathrm{C}$ tablet in $200.0 \mathrm{~mL}$ water and then titrated it with 0.1250 -M $\mathrm{NaOH}$. It required $21.30 \mathrm{~mL}$ of the base to reach the equivalence point. Calculate the mass percentage of the tablet that is impurity.

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Key Concepts

Acid-Base Titration

Acid-base titration is a quantitative analytical technique used to determine the concentration of an acid or a base in solution by gradually adding a titrant of known concentration until the reaction's equivalence point is reached.

Equivalence Point

The equivalence point is the stage in a titration where the amount of titrant added is exactly enough to completely react with the analyte. This concept is key for converting volume and concentration data of the titrant into the moles of analyte present.

Stoichiometry

Stoichiometry involves using the balanced chemical equation to relate the moles of reactants and products. It allows for the calculation of the amount of a compound in a sample based on the titration data.

Molarity and Solution Concentration

Molarity is the number of moles of a solute per liter of solution. Understanding molarity is essential for converting between the volume of titrant used and the moles of substance reacted during the titration.

Percentage Composition and Purity Analysis

Percentage composition involves determining the ratio of the active substance in a sample relative to the total mass, which is crucial for calculating the purity of the sample and quantifying the percentage of impurities present.

Transcript

00:01 So let's do a special type of acid -based reaction via titration.

00:08 Titration is a very accurate way of measuring substances.

00:13 And so we have a reaction here between vitamin c and sodium hydroxide.

00:19 And let's try to figure out, you know, vitamin c people normally take a pill.

00:26 And let's see if there might be any impurities in the vitamin c.

00:31 C.

00:32 Now, when we do this reaction, what we're going to know is that we needed 21 .3 milliliters of sodium hydroxide, and the molarity of that was 0 .1250 to react all of the vitamin c.

01:04 And we know that we have a 500 milligram tablet of vitamin c.

01:11 So let's figure out how much of that 500 milligram tablet was vitamin c.

01:18 And then whatever the difference is must be whatever the impurities are.

01:23 So let's find the moles of sodium hydroxide.

01:28 Then we can find the moles of the vitamin c.

01:32 And then we can find the mass of the vitamin c.

01:37 So we'll start out with our 21 .30 milliliters.

01:45 We need to get that to liters in order to use molarity.

01:49 So every liter is 1 ,000 milliliters.

01:54 Remember, molarity is moles per liter.

01:56 So we have a 0 .125 mole per liter solution of the sodium hydroxide.

02:06 So if we stopped here, that would get us moles of sodium hydroxide...