0.702g of arsenic
an oxide of arsenic mass 0.927g how do i calculate the mass of oxygen that combines with 1 mole of arsenic atoms to form the oxide of arsenic. how many moles of oxygen atoms does this mass represent a
and then using that answer i have to obtain an empiricl formula of oxide
I did get the % as 72 for arsenic
and 25% for oxygen
how do i achieve the above
I think you punched the wrong button.
0.702/0.927 = 75.7% As.
mass oxygen = 0.927 - 0.702 = ??
right?
Two other points? How did you find percent oxygen without have the mass? And why does the percent oxygen and percent arsenic not add to 100%?
yes i did i do get 75.7
i then got 0.225 and when i x 100 i get 22.5
how doi do the rest
the same of 0.702g in a boat heat with oxygen diluted with argon on completion the material turns to white powder, an oxide of arsenic with mass of 0.927g
No.
0.225 g is correct because
mass oxide - mass arsenic = mass oxygen.
0.927 - 0.702 = 0.255g
% oxygen = (mass oxygen/total mass oxide)x100 = 0.255/0.972 = ??
To get the empirical formula, use EITHER percents or masses. Let's do masses.
0.702g As and 0.225 g Oxygen.
Convert these to mols.
0.702g As/atomic mass As = ??
0.225 g oxygen/atomic mass O = ??
When you get those to mol numbers, then divide the smaller number by itself (to make it become 1.00000), then to keep things equal divide the other mol value by the SAME number. That will be the ratio of As to O. Convert that, if necessary, to whole numbers and that will be the empirical formula. Post your work if you get stuck.
You can use percents instead by doing exactly the same procedure. The numbers will be different but the ratios will be the same.
That doesn't answer the question but it's moot at this point anyway. Concentrate on how to work the problem.
do i use the relative atomic mass to convert these to mols
what are mols?
Aren't all atomic masses relative? Yes. Look up As and O on the periodic table. Or go to http://www.webelements.com/
thanks so much
0.702g / 74.9 = 9.372496662 x 10-3
0.225g / 16 = 0.0140623
0.0140623/ 0.0140623 = 1
0.0140623/9.372496662 x10-3 = 1.500379302
so is the answer 1 to 2
Almost but not quite.
First, you didn't divide by the smaller number. 0.00937 is smaller than 0.01406.
(You really don't need to carry that many places. Since you have three numbers for 0.702 you might carry four places, then round at the end.)
Second, if you round 1.5 (as you did) to 2 then you are throwing away 0.5 and you precision is better than that. If I had numbers like 1 to 1.5 (and they will change when you redo it and divide by the smaller number) I would immediately know it was a ratio of 2 to 3 (just think what do I need to multiply 1.5 by to make it a whole number. Of course that is 2 so multiply 1.5 by 2 to get 3.0 and 1 by 2 to get 2 and voila, we have a ratio of 2:3). So your answer of As2O1 would actually be As3O2 with your numbers. Remember this will change when you redo and divide by the smaller number.
Hallo cheating S103 student