Question

How many moles are in 4,475.01 milligrams of an unknown element with a molarmass of 161.49 g/mol?

Answer 1

0.03 moles

Step-by-step explanation:

Given:

The molar mass of the unknown = 161.49 g/mol

Mass of the unknown = 4,475.01 milligrams

Step 1: Convert the mass given from milligram to gram.

Note: 1 milligram = 1 x 10⁻³ gram

So 4,475.01 milligrams will be

`\frac{4475.01\text{ milligrams }*1*10^(-3)\text{ grams}}{1\text{ milligram}}=4.47501\text{ grams}`

Step 2: Calculate the number of moles of the unknown.

The mole of the unknown element can be calculated by the given formula below:

`\text{Mole }=\frac{Mass}{Molar\text{ mass}}`

Substitute the values of mass and molar mass into the formula above:

`\begin{gathered} \text{Mole }=\frac{4.47501\text{ g}}{161.49\text{ g/mol}}=0.027710756\text{ mol} \\ \text{Mole }\approx0.03\text{ mol} \end{gathered}`

Therefore, there are 0.03 moles in 4,475.01 milligrams of an unknown element with a molar mass of 161.49 g/mol4