i dont get any of this... how do i do it? show your work plz
how many moles in each of the following? use correct significant digits
25g of SO22
219g of HCl
35g of CO2
and part two
how many grams in each of the following
0.035 moles of KOH
and party three
calculate the molar mass of each of the following
0.0025moles weighs 0.40g
3.9 *10^3 moles weighs 117kg
can you explain in detail and write it so a young kid can understand it. Im not good at english
Moles! Chemistry?
1st, I believe the SO22 is SO2 ...?
SO2 is a Sulphide Molecule (Compound) = 1 mole.
Atomic masses of Elements are taken from the Periodic Table of Elements to get Molecular Mass of each compound where required. (e.g. S = 32 Atomic mass and 'O' = 16 Atomic mass. We have 1 'S' (32) and 2 'O' = 2 x 16 (32) = a Mol.mass of 64g in 1 mole of SO2 (= 64g/mole)....
1...Mol.mass of SO2 = 32 + (2 x 16) = 64g/mole.
Mass/Mol.mass = moles = 25g/64g/mole = 0.391moles SO2.
2...Mol.mass HCl = 1 + 35.5 = 36.5g/mole.
219g/36.5g-mole = 6.0 moles HCl.
3...Mol.mass CO2 = 12 + (2 x 16) = 44g/mole.
35g/44g-mole = 0.795 moles CO2.
Part 2.
1...Mol.mass KOH = 39 + 16 + 1 = 56g/mole.
Mass/Mol.mass = moles.
Mol.mass x moles = mass.
Mass = 56g/mole x 0.035 moles = 1.96g KOH.
Part 3.
1...Mass/Mol.mass = moles.
0.40g/Mol.mass = 0.0025 moles.
0.40g/0.0025moles = 160 g/mole (Mol. mass).
2...(10³ = 1,000).
3.9 x 1,000 = 3,900moles.
117kg/3,900 moles = 30 g/mole (Mol.mass).
I hope this is clear enough for the youngster.
Reply:If you know how to convert than, this should be easy. You just have to go step by step. Its kind of hard to try to type in HOW to do it on the computer.
25g= # of grams in SO22 (remember there's 1 Sulfur and 22 oxygens), then set that equal to one mole. you can now find the answe. use proportions too!
Reply:I think you have SO2 not SO22, since s has four protons so it takes two electrons from each oxygen. Anyways, back to your question.
Please refer to the periodic table of elements
http://www.dayah.com/periodic/
Part 1)
In order to calculate the number of moles of a compound whose mass is known, you have to first find the molecular mass.
The molecular mass in general is the mass of a specific element in one mole of that element and represented in g/mole. The molecular mass of any compound is the sum of molecular masses of individual elements in that compound each multiplied with the number of occurance of that molecules.
For example SO2 is composed of one "S" molecule and 2 "O" molecules.
In order to find the molecular mass of SO2, we look at the periodic table and we find the molecular masses of "S" and "O" individually.
The molecular mass of "S" is 32 and that of "O" is 16.
This means that the molecular mass of the whole compound SO2 is 1(32) + 2(16) = 64 g/ mole. This means that each mole of SO2 weighs 64 g.
1 mole...............64 g
?? moles...........25 g
If you have 25 g of SO2. This means that we have
(25 g x 1 mole) / 64 g = 0.39 moles.
The others are done exaclty in the same way. Look the molecular masses of H and Cl up in the periodic table.
Mm of H = 1 and Mm of Cl = 35.5
Thus the Mm of HCl is 1(1) +1(35.5) = 36.5 g/moles
This means that we have
(219 x 1) / 36 = 6.08 moles.
Please do the CO2 by yourself for practice.
Part 2)
how many grams in each of the following
0.035 moles of KOH?
You do exactly as before and you find the molecular mass of KOH. You will find that it is 39 + 16 + 1 = 56 g/mole
1 mole .............. 56 g
0.035 moles.......?? g
Thus we have (0.035 x 56)/1 =1.96 g of KOH
Part 3)
The molar mass is the same as the molecular mass. It represents the mass of a compound in 1 mole of that compound..
0.0025 moles ................0.40 g
1 mole ............................?? g
Therefore the molar mass is
(1 mole x 0.4 g) / 0.0025 moles = 160 g/mole
similarly
3.9 *10^3 ...............117000g
1 mole.....................?? g
therefore the molar mass is
(1 x 117000)/ (3.9*10^3) = 30 g/mole
peace
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