Chemistry, 09.07.2019 04:00 mmcdaniels46867

Astudent performs a thermal decomposition experiment using 35.00 g of lithium iodate, liio3. the weight of the crucible decreases by 8.95 g after heating. the theoretical mass of oxygen in liio3 is 9.24 g. what is the percent error in the student's experiment? choose the closest answer.

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Answer from: joyce945

The balanced chemical equation representing the thermal decomposition of Lithium iodate is:

$2LiIO_{3}(s)--2LiI(s)+3O_{2}(g)$

The decrease in weight of crucible in heating can be taken as the mass of oxygen lost on thermal decomposition.

Mass of oxygen formed up on thermal decomposition(actual yield)= 8.95 g

Theoretical yield of oxygen = 9.24 g

Percentage error = $\frac{Theoretical yield (g)-Actual yield (g)}{Theoretical yield (g)}*100$

= $\frac{9.24g-8.95 g}{9.24 g}*100=3.14 %$

Answer from: elizabethann2

The percentage error in the student’s experiment is $\boxed{3.14\;\%}$

Further Explanation:

The five types of chemical reactions are as follows:

1. Combination reactions:

These reactions are also known as a synthesis reaction. These are the reaction in which two or more reactants combine to form a single product. These are generally accompanied by the release of heat so they are exothermic reactions.

Examples of combination reactions are as follows:

(a) ${\text{Ba}}+{{\text{F}}_2}\to{\text{Ba}}{{\text{F}}_2}$

(b) ${\text{CaO}}+{{\text{H}}_2}{\text{O}}\to{\text{Ca}}{\left({{\text{OH}}}\right)_2}$

2. Decomposition reactions:

The opposite of combination reactions is called a decomposition reaction. Here, a single reactant gets broken into two or more products. Such reactions are usually endothermic because energy is required to break the existing bonds between the reactant molecules.

Examples of decomposition reactions are as follows:

(a) $2{{\text{H}}_2}{{\text{O}}_2}\to2{{\text{H}}_2}{\text{O}}+{{\text{O}}_2}$

(b) $2{\text{NaCl}}\to{\text{2Na+C}}{{\text{l}}_2}$

3. Displacement reactions

Also known as replacement or metathesis reactions. Here, one of the reactants gets replaced by the other one. Generally, the more reactive element displaces the less reactive element. Both metals and non-metals can take part in displacement reactions.

Examples of displacement reactions are as follows:

(a) ${\text{Cu}}+{\text{AgN}}{{\text{O}}_3}\to{\text{Ag}}+{\text{Cu}}{\left({{\text{N}}{{\text{O}}_3}}\right)_2}$

(b) ${\text{C}}{{\text{l}}_2}+{\text{KBr}}\to{\text{B}}{{\text{r}}_2}+{\text{KCl}}$

4. Double displacement reactions

These are the reaction in which ions of two compound interchange with each other to form the product. For example, the general double displacement reaction between two compound AX and BY is as follows:

${\text{AX}}+{\text{BY}}\to{\text{AY}}+{\text{BX}}$

Examples of double displacement reactions are as follows:

(a) ${\text{N}}{{\text{a}}_2}{\text{S}}+{\text{HCl}}\to{\text{NaCl}}+{{\text{H}}_2}{\text{S}}$

(b) $2{\text{KOH}}+{\text{Cu}}{\left({{\text{N}}{{\text{O}}_{\text{3}}}}\right)_2}\to2{\text{KN}}{{\text{O}}_3}+{\text{Cu}}{\left({{\text{OH}}}\right)_2}$

5. Combustion reactions:

These are the reactions that take place when hydrocarbons are burnt in the presence of oxygen to form carbon dioxide and water. These are also referred to as burning.

Example of combustion reactions are as follows:

(a) ${\text{C}}{{\text{H}}_4}+{{\text{O}}_2}\to{\text{C}}{{\text{O}}_2}+{{\text{H}}_2}{\text{O}}$

(b) ${{\text{C}}_{10}}{{\text{H}}_{14}}+12{{\text{O}}_2}\to10{\text{C}}{{\text{O}}_2}+4{{\text{H}}_2}{\text{O}}$

The decomposition of lithium iodate occurs as follows:

$2{\text{LiI}}{{\text{O}}_3}\left(s\right)\to2{\text{LiI}}\left(s\right)+3{{\text{O}}_2}\left(g\right)$

It is given that the student observes a decrease in the weight of the crucible during the experiment. This decrease in the crucible can be considered as the mass of oxygen lost during thermal decomposition of lithium iodate. So the actual yield of oxygen during thermal decomposition reaction of is 8.95 g. But the theoretical yield of oxygen is 9.24 g.

The formula to determine the percent error in the experiment is as follows:

${\text{\% error}}=\left({\frac{{{\text{Theoritical yield}}-{\text{Actual yield}}}}{{{\text{Theoritical yield}}}}}\right)\times{\text{100\%}}$ …… (1)

The actual yield of oxygen is 8.95 g.

The theoretical yield of oxygen is 9.24 g.

Substitute these values in equation (1).

$\begin{gathered}{\text{Percentage error}}=\left({\frac{{{\text{9}}{\text{.24 g}}-{\text{8}}{\text{.95 g}}}}{{{\text{9}}{\text{.24 g}}}}}\right)\times{\text{100\%}}\\=\left({\frac{{{\text{0}}{\text{.29 g}}}}{{{\text{9}}{\text{.24 g}}}}}\right)\times{\text{100\%}}\\={\text{3}}{\text{.13852\%}}\\\approx{\mathbf{3}}{\mathbf{.14\%}}\\\end{gathered}$

Learn more:

1. Balanced chemical equation:

2. Oxidation and reduction reaction:

Answer details:

Grade: High School

Subject: Chemistry

Chapter: Chemical reaction and equation

Keywords: LiIO3, O2, LiI, 2LiIO3, 2Li, 3O2, double displacement reaction, combination reaction, combustion reaction, displacement reaction, decomposition reaction, percent error, 35 g, 9.24 g, 8.95 g, 3.14 %, actual yield, theoretical yield, weight of crucible.

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Astudent performs a thermal decomposition experiment using 35.00 g of lithium iodate, liio3. the wei...

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