Alkaline Battery An alkaline battery produces electrical...

Alkaline Battery An alkaline battery produces electrical energy according to this equation. \begin{equation} \mathrm{Zn}(\mathrm{s})+2 \mathrm{MnO}_{2}(\mathrm{s})+\mathrm{H}_{2} \mathrm{O}(\mathrm{l}) \rightarrow \end{equation} \begin{equation} \quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\mathrm{Zn}(\mathrm{OH})_{2}(\mathrm{s})+\mathrm{Mn}_{2} \mathrm{O}_{3}(\mathrm{s}) \end{equation} \begin{equation} \begin{array}{l}{\text { a. Determine the limiting reactant if } 25.0 \mathrm{g} \text { of } \mathrm{Zn} \text { and }} \\ {30.0 \mathrm{g} \text { of } \mathrm{MnO}_{2} \text { are used. }} \\ {\text { b. Determine the mass of } \mathrm{Zn}(\mathrm{OH})_{2} \text { produced. }}\end{array} \end{equation}

Alkaline Battery An alkaline battery produces electrical
energy according to this equation.
\begin{equation}
\mathrm{Zn}(\mathrm{s})+2 \mathrm{MnO}_{2}(\mathrm{s})+\mathrm{H}_{2} \mathrm{O}(\mathrm{l}) \rightarrow
\end{equation}
\begin{equation}
\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\mathrm{Zn}(\mathrm{OH})_{2}(\mathrm{s})+\mathrm{Mn}_{2} \mathrm{O}_{3}(\mathrm{s})
\end{equation}
\begin{equation}
\begin{array}{l}{\text { a. Determine the limiting reactant if } 25.0 \mathrm{g} \text { of } \mathrm{Zn} \text { and }} \\ {30.0 \mathrm{g} \text { of } \mathrm{MnO}_{2} \text { are used. }} \\ {\text { b. Determine the mass of } \mathrm{Zn}(\mathrm{OH})_{2} \text { produced. }}\end{array}
\end{equation}

Key Concepts

Stoichiometry

Stoichiometry is the branch of chemistry that deals with the quantitative relationships between the reactants and products in a chemical reaction. It uses the mole ratios derived from the balanced chemical equation to predict the amounts of substances consumed and produced.

Limiting Reactant

The limiting reactant is the substance in a chemical reaction that is completely used up first, thereby limiting the amount of product that can be formed. Identifying the limiting reactant is crucial for determining the actual yield of a reaction.

Balanced Chemical Equation

A balanced chemical equation represents a chemical reaction where the number of atoms of each element is the same on both sides of the reaction. This is essential for ensuring the conservation of mass and charge and forms the foundation for quantitative analysis in reactions.

Molar Mass and Conversions

Molar mass is the mass of one mole of a substance, typically expressed in grams per mole. It serves as an essential conversion factor to translate between the mass of a substance and the corresponding amount in moles, which is fundamental for quantitative reaction calculations.

Transcript

00:01 In this question, we are given the balanced equation for the reaction between zinc, manganese oxide, manganese 4 oxide, and water to produce zinc hydroxide and manganese 6 oxide.

00:41 Okay? so the complete balanced equation will have an coefficient of 2.

00:51 Here.

00:52 Based on this balanced equation, we need to determine which one is the limiting reagent when 25 grams of zinc are mixed together with 30 grams of manganese 4 oxide.

01:13 Okay? so these are the two reactants that we need to compare and therefore we establish the more relationship between zinc and manganese oxide.

01:25 So we have one mole of zinc reacting with two moles of manganese four oxide.

01:33 Now because we are given grams and then question b, which is to determine the mass of the product, zinc oxide is obtained in grams.

01:44 So it's better to convert the moles to grams and then work with grams thereafter.

01:49 Okay so before we established the the mass ratio the theoretical mass ratio we're going to convert this mold to grams okay so one mold of zinc is converted to grams and we multiply by the atomic mass or the atomic weight of zinc which is 16 65 .39 grams per mole.

02:34 Then we get 65 .39 grams.

02:40 Now we convert the two moles of manganese for oxide to grams.

02:52 For that we multiply by the molar mass of manganese 4 oxide.

02:57 The atomic weight of manganese is 54 .94 plus 2.

03:06 Times the atomic weight of oxygen, which is 16, that's 32.

03:13 We do this little calculation, 54 .94 plus 32, and that's multiplied by two moles.

03:24 And we get, and obviously this is grams per moles, month we cancel, and then we get 173 .88 grams.

03:39 Now we're going to establish the theoretical ratio, theoretical ratio, which is one mole of zinc to two more of manganese oxide, but we are going to do it with the mass...

Please give Ace some feedback