Question

How many moles of potassium are in 78.20 g?

Answer 1

The answer to this question would be: 2 mol

To answer this question, you need to know the molecular weight of Potassium. Molecular weight determines how much the weight of 1 mol of a molecule has. 
Potassium or Kalium molecular weight is 39.1 gram/mol. Then, 78.20gram of potassium should be: 78.20g/ (39.1g/mol)= 2 mol

Answer 2

The number of moles contains 78.20 grams of potassium is $\boxed{2{\text{ moles}}}$.

Further Explanation:

Mole is a measure of the amount of substance. Mole is the relation between the mass of substance and molar mass of substance. It is defined as the mass of a substance in grams divided by its molar mass (g/mol).

The formula to calculate the number of moles is as follows:

${\text{Number of moles}}\;=\;\frac{{{\text{Given mass}}\left({\text{g}}\right)}}{{{\text{molar mass}}\left({{\text{g/mol}}}\right)}}$      ...... (1)

The given mass of the potassium atom is 78.20 grams.

According to the periodic table, the atomic mass of potassium (K) atom is 39.098 amu therefore, the molar mass of the potassium atom is 39.098 g/mol.

The formula to calculate the number of moles of potassium is as follows:

${\text{Number of moles K}}\;=\;\frac{{{\text{Given mass of K}}\left({\text{g}}\right)}}{{{\text{molar mass of K}}\left({{\text{g/mol}}}\right)}}$       …… (2)

Substitute 78.20 g for given mass of K and 39.098 g/mol for molar mass of K in equation (2).

$\begin{gathered}{\text{Number of moles K}}\;=\;\frac{{{\text{Given mass of K}}\left({\text{g}}\right)}}{{{\text{molar mass of K}}\left({{\text{g/mol}}}\right)}}\\=\frac{{78.20{\text{g}}}}{{39.098{\text{ g/mol}}}}\\=2.00{\text{ mol}}\\\end{gathered}$

The value of the number of moles of potassium is 2.00 moles.

Learn more:

1. Determined the mass of ammonia product formed in the reaction: brainly.com/question/6078553

2. Determine how many moles of water produce: brainly.com/question/1405182

Answer details:

Grade: Senior school

Subject: Chemistry

Chapter: Mole concept

Keywords: Potassium, molar mass, moles, atomic mass, number of moles, number of atoms, given mass, ratio, substance, g/mol grams, 78.20 grams, 2 moles, 39.098 g/mol, number of moles of potassium.