Question

Elements A and Z combine to form two different compounds: A2Z3 and AZ2. If 0.15 mol of A2Z3 has a mass of 15.9 g and 0.15 mol of AZ2 has a mass of 9.3 g, what are the atomic masses of A and Z

Answer 1

Question #59694, Chemistry / General Chemistry

Elements A and Z combine to form two different compounds: AZZ3 and AZ2. If 0.15 mol of AZZ3 has a mass of 15.9 g and 0.15 mol of AZ2 has a mass of 9.3 g, what are the atomic masses of A and Z

Answer:

Let atomic mass of element A=X and atomic mass of element Z = Y.

Molar mass of compound A₂Z₃:

$$M_{A2Z3} = 2X + 3Y$$

Molar mass of compound AZ₂:

$$M_{AZ2} = X + 2Y$$

In the task, it is given that:

$$0.15(2X + 3Y) = 15.9 \tag{1}$$

AND

$$0.15(X + 2Y) = 9.3 \tag{2}$$

From the last equation:

$$X = \frac{9.3}{0.15} - 2Y = 62 - 2Y$$

Now we will substitute it into the (1) equation:

$$2(62 - 2Y) + 3Y = \frac{15.9}{0.15}$$ $$124 - 4Y + 3Y = \frac{15.9}{0.15}$$ $$124 - Y = 106$$ $$Y = 18 \text{ [u]}$$

AND

$$X = 62 - 2Y = 62 - 36 = 26 \text{ [u]}$$

Atomic mass of element A is 26 units and atomic mass of element Z is 18 units.

http://www.AssignmentExpert.com/