What is the mass of 5.09 mol of lithium? mass: g

Answer 1

Hi! In order to solve this, you have to use stoichiometry. You know that you have 5.09 mol of Li. When it asks for grams, you use the molar mass. Molar mass comes from the atomic mass of an element. In this instance, because you only have 1 lithium, the atomic mass and molar mass is the same. The atomic mass of Li is 6.94g. Anytime we have 1 mol of an element, it is equal to the atomic mass of that element.

The atomic mass of Li is 6.94 g This question is a mole to gram problem so it will only be one step.

We start with what they give us in the question: 5.09 mol Li

We need to then cancel our units: mol Li. Since we know that 1 mol Li = 6.94 g Li, we can use this to solve the question. Here is how it should be set up:

5.09 mol Li x 6.94 g Li

1 1 mol Li

When we place units diagonal from each other, they cancel out. Thus, mol Li cancels out in this equation and we are left with the units g Li

We then solve like its a normal fraction: 5.09 x 6.94 = 35.3 g Li

Since we only had 1's on the bottom we do not need to divide.

Therefore, the mass of 5.09 mol Li is 35.3 g Li

I hope this helps.