When the element A is burned in an excess of oxygen, the oxide A2O3(s) is formed. 0.5386 g of element A is treated with oxygen and 0.711 g of A2O3 are formed. Identify element A.
.....4A + 3O2 ==> 2A2O3
..0.5386...x.....0.711
x = 0.711 - 0.5386 = 0.1724 g O2.
Convert g O2 to g A2O3. Let A = atomic mass A and O = atomic mass O.
1724 x (2*molar mass A2O3/3 molar mass O) = 0.711. Then
0.1724 x (4A+6O)/6O) = 0.711
Substitute and solve for A. My answer is in the low 70s. Look up the atomic mass on the periodic element to identify the element.
Here is another way.
You have 0.1724 g O2. mols O2 = g/molar mass = 0.1724/32 = ?
Convert mols O2 to mols A2O3. That's ? x (2 mol A2O3/3 mols O2) = ? x 2/3 = ?
Since mols = g/molar mass then molar mass = g/mols = ?. I get approx 198.
If molar mass A2O3 is about 198 (you will have a slightly different number). Subtract 48 for 3 oxygen atoms at 16 each and that will give you 2*atomic mass A. Divide by 2 and look it up on the periodic table.
To identify element A, we can use the concept of stoichiometry.
1. Start by calculating the number of moles of A2O3 formed using its molar mass. The molar mass of A2O3 is 2 * atomic mass of A + 3 * atomic mass of O. Therefore:
Molar mass of A2O3 = (2 * atomic mass of A) + (3 * atomic mass of O)
2. Convert the mass of A2O3 formed (0.711 g) to moles using its molar mass:
Moles of A2O3 = (Mass of A2O3) / (Molar mass of A2O3)
3. Based on the balanced chemical equation, for every 2 moles of A2O3 formed, 4 moles of element A are required. This means that the ratio of moles of A2O3 to moles of A should be 2:4, which simplifies to 1:2.
Moles of A = (Moles of A2O3) * 2
4. Finally, calculate the mass of element A using its molar mass:
Mass of A = (Moles of A) * (Molar mass of A)
By following these steps, you should be able to determine the identity of element A.
To identify the element A, we need to use the given information in the question and calculate the molar mass of A2O3.
First, we need to calculate the moles of A2O3 formed. We can use the given mass of A2O3 (0.711 g) and its molar mass to find the number of moles.
The molar mass of A2O3 can be calculated by adding the molar masses of element A and oxygen together. Let's assume the molar mass of A is 'x' g/mol.
Molar mass of A2O3 = (2 * molar mass of A) + (3 * molar mass of oxygen)
Molar mass of A2O3 = (2 * x g/mol) + (3 * 16 g/mol) [Since the molar mass of oxygen is 16 g/mol]
Now, we can set up an equation to find the moles of A2O3:
0.711 g / molar mass of A2O3 = moles of A2O3
Substituting the above values, we have:
0.711 g / [(2 * x) + (3 * 16)] g/mol = moles of A2O3
Next, we need to calculate the moles of element A. We can use the given mass of A (0.5386 g) and its molar mass.
Moles of A = Mass of A / molar mass of A
Moles of A = 0.5386 g / x g/mol (since the molar mass of A is 'x' g/mol)
Now, based on the reaction, we know that:
2 moles of A ---> 1 mole of A2O3
So, by the stoichiometry of the reaction, we can set up a ratio between the moles of A and moles of A2O3 as follows:
2 moles of A / 1 mole of A2O3 = moles of A / moles of A2O3
Now, we can set up an equation using the above ratio and the calculated values:
2 / 1 = (0.5386 g / x g/mol) / (0.711 g / [(2 * x) + (3 * 16)] g/mol)
Simplifying the equation, we have:
2 = [(0.5386 g * [(2 * x) + (3 * 16)] g/mol) / (x g/mol)] / 0.711 g
Now, we can solve this equation to find the value of x, which is the molar mass of element A. Once we know the molar mass, we can refer to the periodic table to identify the element.