Gram Formula Mass

This lesson covers:

  1. The meaning of 'gram formula mass', which throughout this lesson is called 'relative formula mass'
  2. The meaning of 'relative atomic mass'
  3. How to find the relative atomic mass and relative formula mass using the periodic table
  4. How to find the 'percentage by mass' of an element 

What is the definition of relative atomic mass?

The average mass of all the isotopes of that element

The number of neutrons an element has

The number of protons an element has

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What is the symbol for relative atomic mass?

A

Ar

Mr

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What is the relative atomic mass of carbon (C)?

(You may need a periodic table)

12

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What is the relative atomic mass of potassium (K)?

(You may need a periodic table)

39

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What is the symbol for relative formula mass?

A

Ar

Mr

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What is the relative formula mass of ammonia (NH3)?

(You may need a periodic table)

17

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What is the relative formula mass of calcium carbonate (CaCO3)?

(You may need a periodic table)

100

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What is the percentage mass of carbon (C) in methane (CH4)?

(Ar of carbon = 12, Ar of hydrogen = 1)

75

%

%

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What is the percentage mass of oxygen (O) in calcium carbonate (CaCO3)?

(You may need a periodic table)

48

%

%

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