Question

How many grams of lithium chloride must decompose to produce 30.3 grams of lithium metal? Show all steps of your calculation as well as the final answer.

2LiCl > 2Li+Cl2

Answer 1

185.05 g.

Step-by-step explanation:

• Firstly, It is considered as a stichiometry problem.

• From the balanced equation: 2LiCl → 2Li + Cl₂

• It is clear that the stichiometry shows that 2.0 moles of LiCl is decomposed to give 2.0 moles of Li metal and 1.0 moles of Cl₂, which means that the molar ratio of LiCl : Li is (1.0 : 1.0) ratio.

• We must convert the grams of Li metal (30.3 g) to moles (n = mass/atomic mass), atomic mass of Li = 6.941 g/mole.

• n = (30.3 g) / (6.941 g/mole) = 4.365 moles.

• Now, we can get the number of moles of LiCl that is needed to produce 4.365 moles of Li metal.

• Using cross multiplication:

• 2.0 moles of LiCl → 2.0 moles of Li, from the stichiometry of the balanced equation.

• ??? moles of LiCl → 4.365 moles of Li.

• The number of moles of LiCl that will produce 4.365 moles of Li (30.3 g) is (2.0 x 4.365 / 2.0) = 4.365 moles.

• Finally, we should convert the number of moles of LiCl into grams (n = mass/molar mass).

• Molar mass of LiCl = 42.394 g/mole.

• mass = n x molar mass = (4.365 x 42.394) = 185.05 g.

Answer 2

Answer: 185.66 grams of Lithium chloride must decompose.

Step-by-step explanation:

To calculate the moles, we use the following equation:

`\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}`

Moles of Lithium:

Given mass of lithium = 30.3 grams

Molar mass of lithium = 6.91 g/mol

Putting values in above equation, we get:

`\text{Number of moles}=(30.3g)/(6.91g/mol)=4.38moles`

For the given chemical reaction, the equation follows:

`2LiCl\rightarrow 2Li+Cl_2`

By Stoichiometry of the reaction:

2 moles of lithium metal are produced by 2 moles of lithium chloride

So, 4.38 moles of lithium metal are produced by =
`(2)/(2)* 4.38=4.38moles` of lithium chloride.

Now, to calculate the mass of lithium chloride, we use the moles equation:

Molar mass of lithium chloride = 42.39 g/mol

Putting values in above equation, we get:

`4.38mol=\frac{\text{Given mass}}{42.39g/mol}`

Mass of lithium chloride = 185.66 grams

Hence, Mass of lithium chloride decomposed is 185.66 grams.