Related Topics: More Chemistry Lessons

In these lessons, we will learn

**What is relative formula mass and relative molecular mass?**

The**relative formula mass** of a substance is the sum of the relative atomic masses of the elements present in a formula unit. The symbol for relative formula mass is *M*_{r.
}If the substance is made of simple molecules, this mass may also be called the **relative molecular mass**.
**How to calculate the relative formula mass?**

_{2}. Each molecule contains 2 hydrogen atoms.

The relative mass formula of hydrogen gas is

_{2}O. Each molecule contains 2 hydrogen atoms and 1 oxygen atom.

The relative mass formula of water is

^{+}Cl^{-}.

The relative mass formula of sodium chloride is

**How to find the Percent Mass of Elements in a compound?**

How to use*M*_{r} to calculate the **percent mass of an element** in a compound?

Mass of hydrogen in the formula = 28

Mass of hydrogen as a fraction of the total =

Mass of hydrogen as percentage of total mass

Mass of O as a fraction of the total =

Mass of O as percentage of total mass

The following video gives an example of calculating percent mass of elements in a compound.

**How find the percent of an element in a compound? **

Finding the percent by mass means finding the mass of the elements in the compound and adding the masses for the total mass.
**How to calculate the Mass Percent of an Element in a Compound?**

Mass Percent Composition of an Element in a Compound

How do calculate the mass percent composition (or simply, the mass percent) of an element in a compound.

**How to find the Percent Mass of Water in a compound?**

How to use*M*_{r} to calculate the **percent mass of water** in a compound?

Mass of water in the formula =

Mass of water as a fraction of the total =

Mass of hydrogen as percentage of total mass

**How to calculate the Water of Crystallization?**

This video outlines how to determine the percent, by mass, of water trapped in a hydrate's crystal lattice.
This video shows you how to calculate the percentage of water in the formula of a hydrated compound.

Compounds in this video CuSO_{4}.5H_{2}O,
CaCl_{2}.2H_{2}O,
KAl(SO_{4})_{2}.12H_{2}O

You can use the free Mathway widget below to practice Algebra or other math topics. Try the given examples, or type in your own problem and check your answer with the step-by-step explanations.

In these lessons, we will learn

- how to calculate the relative formula mass or relative molecular mass
- how to use the relative molecular mass to calculate the percent mass of an element in a compound
- how to use the relative molecular mass to calculate the percent mass of water in a compound

The

*Example: *

What is the relative mass formula of hydrogen gas? (Relative atomic mass: H = 1)

*Solution: *

The relative mass formula of hydrogen gas is

*Example: *

What is the relative mass formula of water? (Relative atomic masses: H = 1, O = 16)

*Solution: *

The relative mass formula of water is

*Example: *

What is the relative mass formula of sodium chloride? (Relative atomic masses: Na = 23, Cl = 35.5)

*Solution: *

The relative mass formula of sodium chloride is

How to use

*Example: *

What percentage of the mass of ammonium nitrate is nitrogen? (The formula for ammonium nitrate is NH_{4}NO_{3}, Relative atomic masses: H = 1, O = 16, N = 14)

*Solution: *

Mass of hydrogen in the formula = 28

Mass of hydrogen as a fraction of the total =

Mass of hydrogen as percentage of total mass

*Example: *

What percentage of the mass of O in NaNO_{3}? (Relative atomic masses: Na = 23, O = 16, N = 14)

*Solution: *

Mass of O as a fraction of the total =

Mass of O as percentage of total mass

The following video gives an example of calculating percent mass of elements in a compound.

Finding the percent by mass means finding the mass of the elements in the compound and adding the masses for the total mass.

Mass Percent Composition of an Element in a Compound

How do calculate the mass percent composition (or simply, the mass percent) of an element in a compound.

How to use

*Example: *

What percentage of the mass of magnesium sulfate is water? (Given that the formula for magnesium sulfate is , Relative atomic masses: H = 1, O = 16, S = 32, Mg = 24)

*Solution:*

Mass of water in the formula =

Mass of water as a fraction of the total =

Mass of hydrogen as percentage of total mass

This video outlines how to determine the percent, by mass, of water trapped in a hydrate's crystal lattice.

Compounds in this video CuSO

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You can use the free Mathway widget below to practice Algebra or other math topics. Try the given examples, or type in your own problem and check your answer with the step-by-step explanations.

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