Question

how many moles of lithium are in 25 g of lithium? 25 g li (\frac{1 mol}{6.94 g}) = 25 \div 6.94 = 3.6 mol li what is the mass of 11.5 moles of lithium? 11.5 mol li (\frac{}{}) multiple - choice question what part of the conversion factor will go on the denominator? 6.94 grams 1 mol

Explanation:

Step1: Recall molar - mass concept

The molar mass of lithium (Li) is 6.94 g/mol. To find the mass of a given number of moles of lithium, we use the conversion factor based on the molar - mass relationship.

Step2: Set up the conversion

We know that 1 mole of Li has a mass of 6.94 g. So the conversion factor to convert moles of Li to grams of Li is $\frac{6.94\ g}{1\ mol}$. For 11.5 moles of Li, we multiply by this conversion factor: $11.5\ mol\ Li\times\frac{6.94\ g}{1\ mol}$.

Step3: Calculate the mass

$11.5\times6.94 = 79.81$ g.

For the multiple - choice question:
To convert from moles to grams, the conversion factor is $\frac{\text{mass in grams}}{\text{1 mole}}$. So when converting 11.5 moles of Li to grams, the part of the conversion factor that goes in the denominator is 1 mol.

Answer:

The mass of 11.5 moles of lithium is 79.81 g.
For the multiple - choice question: 1 mol