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Chemistry homework help (need quick answers and explanations please)?
The directions say "Calculate the number of moles in each of the following masses:" and then goes on to have four problems.
A-
64.1g of aluminum; ans- 2.38 mol Al
B-
28.1 g of silicon; ans- 1.00 mol Si
C-
0.255g of sulfur; ans- 7.95 x 10^-3 mol S
D-
850.5g of zinc; ans- 13.01 mol Zn
The answers are there, I just need to know the steps on how to get to those answers. Any accurate help would be greatly appreciated. Thank you for looking and I hope someone can help me soon, since this assignment is due tomorrow.
Thank you!
That helped. ^_^
2 Answers
- Anonymous1 decade agoFavorite Answer
No problem. Simply divide the mass by the molecular weight (or atomic mass in these cases). So for Al
64.1 g / 26.98 g/mol = 2.38 mol
Just look up the atomic weights for the others and you will be all set!
Best of luck.
Source(s): http://en.wikipedia.org/wiki/Aluminium - 1 decade ago
Very easy!! Just understand the concept!!
Mole is a number, like when you say : a dozen spoons, you mean 12 spoons, when you say a mole of spoons you mean a huge pile of spoons!! (602 000 000 000 000 000 000 000 spoons to be precise!)
We don't use this number cause its so big! We just say moles!
On each atom on the periodic table has its on molar mass.
Molar mass of an atom is the weight of 1 mole of that atom.
Thus, hydrogens molar weight is 1.01g/mole, thus, its the same ase saying 1 mole of Hydrogen atoms weigh 1.01 gram.
Or 602 000 000 000 000 000 000 000 of Hydrogen atoms weigh 1.01 grams.
The molar mass of oxygen is 16 mole/gram. So, one mole of oxygen atoms weighs 16 grams. And 2 mole of oxygen is twice as much atoms, so the weight will obviously be twice as much! So 2 mole oxygen will weigh 32gram.
Just do the opposite now. Ask yourself, how many moles are in 32 grams of Oxygen?
You divide the mass by molar maas (molar mass is on your periodic table)
How many moles of oxygen is in 63g Oxygen
How many moles of oxygen are in 1 gram of oxygen?
Mole= Mass ÷ molar mass
Molar mass = mole ÷ mass
Mass = mole x molar mass
Checked all your answers! They are all correct!
Hope you understand the concept
Sorry if my detailed explanation insults you intelligence!
