how do i calculate %of arsenic and oygen by mass and chem composition of the oxide

that has been formed
0.702 sample of arsenicheated, material in boat, oxide of arsenic with mass of 0.927g

please help

%As = [(mass As)/mass oxide]x100=??
%O = [(mass O)/mass oxide]x100=??

From your data, it appears mass As = 0.702g and mass of oxide is 0.927g. Check me out on that. I may not interpret your numbers correctly.

thanks but is it 0.702/ 0.927 = 75.728155

but what figures do i use to work out the % of oxygen

If 0.927 g is the mass of the As after heating (and the mass of the boat is not in that number, I hope), then 0.927 - 0.720 = mass oxygen that must have been added. Right?

am i right in saying that
% as is 0.702 divided by 0.927 x 100
= 75.7%

and the %oxygen is 0.927 - 0.720
= 0.0207 divided by 0.927
= 0.22%

or am i really thick lol

sorry i forgot to x it by 100

so is the answer 22.33 %

Yes, 75.7% As is correct.
I'm afraid I made a typo in my last post and you didn't catch it.
mass oxygen = 0.927 - 0.702 (not 0.720 as I typed)= 0.225, then
% oxygen = (0.225/0.927)x100 = a little different than 22% but not by much. Of course you know that %As + %O should add to 100%.

Hallo cheating S103 'student'Try reading B6

I apologize for any confusion caused by my previous response. To calculate the percentage of arsenic and oxygen by mass in the oxide, you can follow these steps:

1. Determine the mass of arsenic (As). In this case, it is given as 0.702 g.

2. Determine the mass of the oxide. In this case, it is given as 0.927 g.

To calculate the percentage of arsenic (%As), use the formula:
%As = (mass of As / mass of oxide) x 100

Substituting the values:
%As = (0.702 g / 0.927 g) x 100 = 75.7%

Therefore, the mass percentage of arsenic in the oxide is 75.7%.

To calculate the percentage of oxygen (%O), you need to find the mass of oxygen in the oxide. To do this:

1. Subtract the mass of arsenic from the mass of the oxide:
Mass of oxygen = Mass of oxide - Mass of arsenic
Mass of oxygen = 0.927 g - 0.702 g = 0.225 g

2. Calculate the percentage of oxygen:
%O = (mass of oxygen / mass of oxide) x 100

Substituting the values:
%O = (0.225 g / 0.927 g) x 100 = 24.3% (rounded to two decimal places)

Therefore, the mass percentage of oxygen in the oxide is 24.3%.

Note that the sum of the percentage of arsenic and the percentage of oxygen will not be exactly 100% due to rounding errors. In this case, the sum is approximately 100%.