A small amount of methane gas is burned in a closed, airtight container. The container is sitting on a digital scale.

Question

How will the reading on the scale change after the chemical reaction?

Responses

The scale reading will not change.
The scale reading will not change.

The scale reading will show an increase in mass.
The scale reading will show an increase in mass.

The scale reading will show a decrease in mass.
The scale reading will show a decrease in mass.

The scale reading will show a mass of zero.

Answer 1

The correct response is:

The scale reading will not change.

When methane gas is burned in a closed, airtight container, the total mass of the system remains the same. The chemical reaction converts methane and oxygen into carbon dioxide and water, but since the container is closed, all reactants and products remain within the system. Therefore, although energy is released in the form of heat and light, the mass is conserved, and there will be no change in the reading on the digital scale.