Moles of LiH & LiAlH4: Calculations and Solutions

In summary, the question asks for the number of moles of LiH needed to produce 1 mole of LiAlH4, and the second question asks how many moles of LiAlH4 can be produced from 6 moles of LiH. The equation for the reaction is LiH + AlCl3 -> LiAlH4 + 3HCl, with a 4:1 ratio between LiH and LiAlH4. From the given information, it can be calculated that 1.5 moles of LiH are needed to produce 1 mole of LiAlH4. The variable xx represents AlCl3, as clarified in the conversation.
  • #1
BittersweetLove
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Homework Statement





*How many moles of LiH are required to make 1 mole of LiAlH4?


* 6 moles of LiH will produce how many moles of LiAlH4?


Can someone help me get started on these?
 
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  • #2
You start by writing the balancing the relevant equation. Can you do that for the above reaction?
 
  • #3
I am learning the same stuff in class, I can clearly see from what is written that there is a 4 to 1 ratio, so I think we get 1.5 moles. What I don't see is how the equation works. I wrote it out and somethings seems missing.
LiH + Alxx ----> LiAlH4 + xx
I got myself a bit confused, should there be something for xx or is it just Al?

P.S. I would not normally encroach on someone elses question, but since two weeks have passed, I figured it would be ok.
 
Last edited:
  • #4
Good thinking. Alxx is actually [itex]AlCl_3[/itex].
 

What is the molar mass of LiH?

The molar mass of LiH (lithium hydride) is 7.95 g/mol. This can be calculated by adding the atomic masses of lithium (6.94 g/mol) and hydrogen (1.01 g/mol) and multiplying by the number of atoms in the compound (1 lithium atom and 1 hydrogen atom).

How do you calculate the number of moles of LiAlH4?

To calculate the number of moles of LiAlH4 (lithium aluminum hydride), you need to know the mass of the compound and its molar mass. Then, divide the mass by the molar mass. For example, if you have 10 grams of LiAlH4 and its molar mass is 37.95 g/mol, the number of moles would be 10 g / 37.95 g/mol = 0.26 mol.

What is the purpose of calculating moles in chemistry?

Calculating moles is important in chemistry because it allows us to measure and compare the amount of substances in a chemical reaction. This helps us understand the quantities of reactants and products involved and predict the outcome of a reaction.

What is the difference between LiH and LiAlH4?

The main difference between LiH and LiAlH4 is the number of elements present in each compound. LiH is composed of only lithium and hydrogen, while LiAlH4 contains lithium, aluminum, and hydrogen. Additionally, LiAlH4 is a more powerful reducing agent than LiH due to the presence of aluminum.

How do you prepare a solution of LiAlH4?

To prepare a solution of LiAlH4, you need to first dissolve the compound in a suitable solvent, such as ether or tetrahydrofuran (THF). This will create a suspension of LiAlH4 particles in the solvent. The solution can then be used in reactions as a reducing agent. It is important to handle LiAlH4 with caution as it is a highly reactive and flammable substance.

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