3.2 Ar/Mr and % composition

​A_r and M_r

Multiple Choice

What does Ar represent?

• Relative mass

• Relative weight

• Relative atomic mass

• Relative molecular mass

Multiple Choice

The relative atomic mass is the mass of the atom of an element compared to 1/12th of the mass of a carbon atom.

• True

• False

Why do we use relative atomic mass and not actual mass?

Why do you think C-12 atom was used and not hydrogen?
https://www.youtube.com/watch?v=JRjDE75CDgw&t=18s

Fill in the Blank

What is the Ar of an oxygen atom?

Multiple Choice

The Ar of nitrogen gas is 14.

• True

• False

Fill in the Blank

State the Mr of CO₂

Multiple Choice

The Mr of ammonia gas (NH₃) is 17 g.

• True

• False

Fill in the Blank

State the Mr of SiO₂

Fill in the Blank

State the Mr of CaCO₃

% Composition

Multiple Choice

State the % composition of Carbon in calcium carbonate.

[Mr of CaCO₃: 100]

• 12%

• 16%

• 48%

• 40%

Fill in the Blank

State the % composition of oxygen in water.

Write your answer to 1 d.p.

.

%

Fill in the Blank

State the % composition of hydrogen in water.

Write your answer to 1 d.p.

.

%

Fill in the Blank

State the % composition of hydrogen in methane, CH₄

%