Understanding Mass Percent in Chemistry

What is the formula for calculating the mass percent of an element in a compound?

• Mass of element divided by mass of compound, multiplied by 100

• Mass of compound divided by mass of element, multiplied by 100

• Mass of element plus mass of compound, multiplied by 100

• Mass of compound minus mass of element, multiplied by 100

In the example of water decomposition, what is the mass percent of hydrogen in water?

• 7.1%

• 11.2%

• 88.8%

• 56.1%

How do you find the mass percent of oxygen in water if you know the mass percent of hydrogen?

• Subtract the mass percent of hydrogen from 100%

• Divide the mass percent of hydrogen by 100%

• Add the mass percent of hydrogen to 100%

• Multiply the mass percent of hydrogen by 100%

What is the chemical formula for magnesium chloride?

• MgCl

• Mg2Cl

• Mg2Cl2

• MgCl2

What is the mass percent of magnesium in magnesium chloride?

• 35.45%

• 50%

• 25.53%

• 74.47%