2.7k views
0 votes
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

2 Answers

5 votes

Answer:

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.
User Ben DeMott
by
8.6k points
1 vote

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.

User Bgossit
by
8.4k points
Welcome to QAmmunity.org, where you can ask questions and receive answers from other members of our community.