Apply Students conducted a lab to investigate limiting and...

Apply Students conducted a lab to investigate limiting and excess reactants. The students added different volumes of sodium phosphate solution $\left(\mathrm{Na}_{3} \mathrm{PO}_{4}\right)$ to a beaker. They then added a constant volume of cobalt(II) nitrate solution $\left(\mathrm{Co}\left(\mathrm{NO}_{3}\right)_{2}\right),$ stirred the contents, and allowed the beakers to sit overnight. The next day, each beaker had a purple precipitate at the bottom. The students decanted the supernatant from each beaker, divided it into two samples, and added one drop of sodium phosphate solution to one sample and one drop of cobalt(II) nitrate solution to the second sample. Their results are shown in Table $11.5 .$ \begin{equation} \begin{array}{l}{\text { a. Write a balanced chemical equation for the reaction. }} \\ {\text { b. Based on the results, identify the limiting reactant }} \\ {\text { and the excess reactant for each trial. }}\end{array} \end{equation}

Apply Students conducted a lab to investigate limiting
and excess reactants. The students added different
volumes of sodium phosphate solution $\left(\mathrm{Na}_{3} \mathrm{PO}_{4}\right)$ to a
beaker. They then added a constant volume of cobalt(II) nitrate solution $\left(\mathrm{Co}\left(\mathrm{NO}_{3}\right)_{2}\right),$ stirred the contents, and
allowed the beakers to sit overnight. The next day, each
beaker had a purple precipitate at the bottom. The students decanted the supernatant from each beaker, divided it into two samples, and added one drop of sodium
phosphate solution to one sample and one drop of
cobalt(II) nitrate solution to the second sample. Their
results are shown in Table $11.5 .$
\begin{equation}
\begin{array}{l}{\text { a. Write a balanced chemical equation for the reaction. }} \\ {\text { b. Based on the results, identify the limiting reactant }} \\ {\text { and the excess reactant for each trial. }}\end{array}
\end{equation}

Key Concepts

Excess Reactant

An excess reactant is the substance present in a quantity greater than needed for the reaction to proceed to completion. It remains partially unreacted because the reaction stops once the limiting reactant is entirely consumed. Recognizing excess reactants helps in optimizing chemical processes and minimizing waste.

Stoichiometry

Stoichiometry is the quantitative relationship between reactants and products in a chemical reaction, based on the balanced chemical equation. It involves calculations that relate the amounts of substances involved and is essential for determining yields, scaling reactions, and identifying limiting or excess reactants.

Balanced Chemical Equation

A balanced chemical equation expresses a chemical reaction with equal numbers of atoms for each element on both sides, adhering to the law of conservation of mass. It uses stoichiometric coefficients to indicate the proportions of reactants and products, which is essential for predicting the amounts of substances consumed and produced in a reaction.

Limiting Reactant

The limiting reactant in a chemical reaction is the substance that is completely consumed first, thereby limiting the amount of product that can be formed. Identifying the limiting reactant is crucial in stoichiometry as it determines the maximum yield of the reaction regardless of the excess amounts of the other reactants.

Transcript

00:01 This question relates to the reaction between sodium phosphate and cobalt 2 nitrate.

00:11 First, to answer question a, we need to write the balanced equation for this reaction.

00:20 So we have sodium 3 phosphate reactant with cobalt 2 nitrate.

00:31 This reaction produces a precipitate.

00:36 So these two reactants are dissolved in water.

00:39 They are in equal solution.

00:42 And the reaction between them two produces a precipitate of cobalt to phosphate, which is purple, and sodium nitrate, which remains in solution.

01:05 Okay? equals.

01:07 So we need to balance this react this equation.

01:12 We have three sodium, only one, we place a three.

01:16 Then we verify nitrate, we have three nitrate, but two here.

01:21 So we need to exchange the coefficients.

01:28 We need to place a three here.

01:32 Now we have six, and then we need to have then a six here.

01:40 By having a six in front of sodium nitrate, we unbalanced sodium, so we need to place a two here.

01:51 Now we verify the phosphate to phosphate, two phosphate, two phosphate.

01:55 So this is the balanced reaction.

01:58 In question b, we need to determine which of these two reactants is the limiting reactant or the reactant in excess based on information provided on four experiments or trial in the first experiment you mix 5m .l of sodium phosphate with 10m.

02:21 Of cobalt 2 nitrate...

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