Law of Constant Composition

Using improved chemistry equipment in the late 1700s, chemists observed that mass is neither created nor destroyed in a chemical reaction. This scientific law is called the law of

• definite proportions.

• gravity.

• conservation of mass.

• conservation of momentum.

Tags

NGSS.HS-PS1-7

The fact that every sample of a particular chemical compound contains the same elements in exactly the same proportions by mass is known as the law of

• conservation of energy.

• conservation of mass.

• atomic theory.

• definite proportions.

What law states that, regardless of the amount, a compound is always composed of the same elements in the same proportion (or percentage) by mass?

• Law of definite proportions

• Law of conservation of mass

• Law of multiple proportions

• Law of mass action

Which of the following illustrates the Law of Conservation of Matter?

• 
• 
• 

Tags

NGSS.HS-PS1-7

A pure sample of ammonia contains 14 g of nitrogen and 3 grams of hydrogen. A second sample of pure ammonia contains 28 g nitrogen and 6 g of hydrogen. This is an example of the

• law of universal gravitation

• law of multiple proportions

• law of definite proportions

• law of mass action

Carbon dioxide (CO₂) is always 27.3% carbon by mass. Which one of the following correctly expresses this percentage as a ratio or proportion?

• 27.3 g C / 100 g CO₂

• 27.3 g CO₂ / 100 g C

• 72.7 g C / 100 g CO₂

• 27.3 g C / 72.7 g O

Tags

NGSS.HS-PS1-7

Carbon dioxide (CO₂) is always 27.3% carbon by mass. Based on this ratio or proportion, how many grams of carbon are there in a 25.0 g sample of CO₂?

• 8.33 g C

• 6.82 g C

• 109.2 g C

• 13.7 g

Aluminum oxide (Al₂O₃) is 52.9 % aluminum by mass. How many grams of aluminum would be present in a 60.0 gram sample of aluminum oxide?

• 28.24 g Al

• 24.00 g Al

• 31.74 g Al

• 40.00 g Al