Question

You are performing an experiment in a lab to attempt a new method of producing pure elements from compounds. The only problem is that you do not know what element will form. By your previous calculations you know that you will have 3 moles of product. When it is complete, you weigh it and determine you have 209.1 grams. What element have you produced?

Answer 1

Answer:

The element produced is gallium, Ga

Explanation:

Given:

Moles of the product = 3 moles

Weight of the product = 209.1 g

To determine:

The identity of the product formed i.e. the unknown element

Calculation:

The identity of element can be deduce from its atomic weight and comparing the calculated weight to that of the elements in the periodic table.

$Number\ of\ moles = \frac{mass\ of\ the\ element}{atomic\ weight}$

$Atomic\ weight = \frac{mass\ of\ the\ element}{number\ of\ moles}$

In this case:

$Atomic\ weight = \frac{209.1\ g}{3\ moles} = 69.7\ g/mol$

From the periodic table, the element with an atomic mass = 69.7 g/mol is gallium, Ga

Answer 2

You need to calculate the atomic weight of that element.

number of moles = mass / atomic weight

atomic weight = mass / number of moles

atomic weight = 209.1 / 3 = 69.7 g/mol

The element produced will be gallium, Ga.