unknown element X combines with oxygen to form the compund XO2. If 44.0 grams of element X combines with 8.00 grams of oxygen, what is the atomic mass of element X?
X + O2 ==> XO2
8.00 g x (1 mol O2/32 g O2) = 0.25 mol O2.
44.0 g element X must represent 0.25 mol element X.
Check my thinking.
Your thinking is correct. To find the atomic mass of element X, you need to determine the number of moles of element X. You already calculated that 8.00 grams of oxygen represents 0.25 moles of oxygen.
Since you know that element X and oxygen combine in a 1:2 ratio to form XO2, you can deduce that the number of moles of element X is half of the number of moles of oxygen. So, 0.25 moles of oxygen corresponds to 0.25/2 = 0.125 moles of element X.
Now, you need to use this number of moles of element X (0.125 mol) and the given mass of 44.0 grams to calculate the atomic mass of element X.
To find the atomic mass, you can use the formula:
Atomic mass = Mass (in grams) / Number of moles
Atomic mass X = 44.0 g / 0.125 mol = 352 g/mol
Therefore, the atomic mass of element X is 352 grams/mol.