Percent Composition and Molar Mass of Magnesium Nitrate

The video tutorial explains how to calculate the percent composition by mass of each element in magnesium nitrate (Mg(NO3)2). It covers the calculation of molar mass for magnesium, nitrogen, and oxygen, and demonstrates how to use these values to find the percent composition of each element in the compound. The tutorial emphasizes the importance of multiplying by the number of atoms and dividing by the compound's molar mass, followed by multiplying by 100 to convert to a percentage. The video concludes with a reminder that the sum of the percent compositions should be close to 100%.

What is the first step in finding the percent composition by mass of an element in a compound?

• Find the molar mass of the compound

• Find the molar mass of the element

• Count the number of molecules

• Calculate the volume of the compound

How many magnesium atoms are present in magnesium nitrate?

• Two

• Three

• One

• Four

What is the percent composition by mass of magnesium in magnesium nitrate?

• 64.72%

• 16.39%

• 18.89%

• 20.15%

How many nitrogen atoms are present in magnesium nitrate?

• One

• Two

• Three

• Four

What is the percent composition by mass of nitrogen in magnesium nitrate?

• 18.89%

• 20.15%

• 64.72%

• 16.39%

How many oxygen atoms are present in magnesium nitrate?

• Eight

• Six

• Four

• Two

What is the percent composition by mass of oxygen in magnesium nitrate?

• 20.15%

• 16.39%

• 18.89%

• 64.72%

What should the sum of the percent compositions of all elements in a compound be?

• 75%

• 150%

• 50%

• 100%

Which element has the highest percent composition by mass in magnesium nitrate?

• Magnesium

• Oxygen

• Hydrogen

• Nitrogen

What is the molar mass of magnesium nitrate used in the calculations?

• 18.89 g/mol

• 64.72 g/mol

• 148.33 g/mol

• 24.31 g/mol