Stoichiometry?
LiOH + HBr -> LiBr + Water
If I start with 10 Grams of Lithium hydroxide how many grams of Lithium Bromide will be produced?
Could you please explain the process of solving too cause this is kinda hard for me.
Answer:
From the equation one mole of LiOH makes one mole of LiBr
So its a ratio of 1:1
How find how many moles of LiOH they are.
Moles of LiOH = the wight of LiOH / molecular mass of LiOH
Now you need to know how many number of moles of LiBr are produced
As its a 1:1 ratio
No. of moles of LiBr produced = No. of moles of LiOH x 1
Now you have to convert the no of moles of LiBr back into weight.
Weight of LiBr produced = No. of Moles of LiBr produced x molecular weight of LiBr
Ok these are the formulas now you have to do the maths!
To start you need to balance the equation. In this case the equation is already balanced so
LiOH + HBr = LiBr + H2O
From this 1 mole of LiOH will result in 1 mole of LiBr
Moles of LiOH = mass/ MW
=10/(7+16+1)
=0.42
Moles of LiBr produced will then be 0.42
Rearranging the equation
Mass LiBr = MW * moles
= (7+80) * 0.42
= 36g
You can approach this like a unit conversion problem.
The only way you can go from LiOH to LiBr, is if you are in mol (because mol is just a number (like dozen), and the balanced equation tells you that for every 1 mol of LiOH and one mol of HBr you will get 1 mol of LiBr and 1 mol of water.
So, first you need to find the number of LiOH molecules, then you can find how many LiBr molecules you should get, and last, how many g of LiBr that is.
convert g of LiOH to mol of LiOH, using the molecular weight, 23.95 g/ mol (add the molecular masses of Li, O and H to find the molecular weight of LiOH: 6.941 g/mol Li + 16.00 g/mol O + 1.008 g/mol H = 23.95 g/mol LiOH).
10 g LiOH * (1 mol LiOH / 23.95 g LiOH)
= 0.4175 mol LiOH
convert mol LiOH to mol LiBr, using the balanced equation:
0.4175 mol LiOH * (1 mol LiBr / 1 mol LiOH)
= 0.4175 mol LiBr
now find how many grams 0.4175 mol of LiBr is:
find the molecular weight of LiBr:
6.941 g/mol Li + 79.90 g/mol Br = 86.84 g/mol LiBr
now use that to convert 0.4175 mol LiBr to g LiBr:
0.4175 mol LiBr * (86.84 g LiBr / 1 mol LiBr)
=36.26 g LiBr
~ 36 g LiBr
For each step I used a fraction (conversion factor) to get to the units I wanted. I set up the fraction by putting the unit I was in on the bottom, and the unit I wanted, on the top. This way, the units I didn't want would cancel, and I was left with the unit I wanted.
REMEMBER:
mass A => mol A => mol B => mass B
the only way to go from A to B is when you are in moles (because that is just a number, and that is all that the balanced equation tells you, is a relationship between the numbers of each ). It is like a cheese sandwich, you need 2 slices of bread and one slice of cheese, to get 1 sandwich ( 2 bread + 1 cheese = 1 sandwich). It doesn't matter how much they weigh, all that matters it that you have 2 slices of bread and one slice of cheese.
Hope this helps!
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If I start with 10 Grams of Lithium hydroxide how many grams of Lithium Bromide will be produced?
Could you please explain the process of solving too cause this is kinda hard for me.
Answer:
From the equation one mole of LiOH makes one mole of LiBr
So its a ratio of 1:1
How find how many moles of LiOH they are.
Moles of LiOH = the wight of LiOH / molecular mass of LiOH
Now you need to know how many number of moles of LiBr are produced
As its a 1:1 ratio
No. of moles of LiBr produced = No. of moles of LiOH x 1
Now you have to convert the no of moles of LiBr back into weight.
Weight of LiBr produced = No. of Moles of LiBr produced x molecular weight of LiBr
Ok these are the formulas now you have to do the maths!
To start you need to balance the equation. In this case the equation is already balanced so
LiOH + HBr = LiBr + H2O
From this 1 mole of LiOH will result in 1 mole of LiBr
Moles of LiOH = mass/ MW
=10/(7+16+1)
=0.42
Moles of LiBr produced will then be 0.42
Rearranging the equation
Mass LiBr = MW * moles
= (7+80) * 0.42
= 36g
You can approach this like a unit conversion problem.
The only way you can go from LiOH to LiBr, is if you are in mol (because mol is just a number (like dozen), and the balanced equation tells you that for every 1 mol of LiOH and one mol of HBr you will get 1 mol of LiBr and 1 mol of water.
So, first you need to find the number of LiOH molecules, then you can find how many LiBr molecules you should get, and last, how many g of LiBr that is.
convert g of LiOH to mol of LiOH, using the molecular weight, 23.95 g/ mol (add the molecular masses of Li, O and H to find the molecular weight of LiOH: 6.941 g/mol Li + 16.00 g/mol O + 1.008 g/mol H = 23.95 g/mol LiOH).
10 g LiOH * (1 mol LiOH / 23.95 g LiOH)
= 0.4175 mol LiOH
convert mol LiOH to mol LiBr, using the balanced equation:
0.4175 mol LiOH * (1 mol LiBr / 1 mol LiOH)
= 0.4175 mol LiBr
now find how many grams 0.4175 mol of LiBr is:
find the molecular weight of LiBr:
6.941 g/mol Li + 79.90 g/mol Br = 86.84 g/mol LiBr
now use that to convert 0.4175 mol LiBr to g LiBr:
0.4175 mol LiBr * (86.84 g LiBr / 1 mol LiBr)
=36.26 g LiBr
~ 36 g LiBr
For each step I used a fraction (conversion factor) to get to the units I wanted. I set up the fraction by putting the unit I was in on the bottom, and the unit I wanted, on the top. This way, the units I didn't want would cancel, and I was left with the unit I wanted.
REMEMBER:
mass A => mol A => mol B => mass B
the only way to go from A to B is when you are in moles (because that is just a number, and that is all that the balanced equation tells you, is a relationship between the numbers of each ). It is like a cheese sandwich, you need 2 slices of bread and one slice of cheese, to get 1 sandwich ( 2 bread + 1 cheese = 1 sandwich). It doesn't matter how much they weigh, all that matters it that you have 2 slices of bread and one slice of cheese.
Hope this helps!
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