Physical Science Midterm

Front

What is a combustion reaction?

Back

A combustion reaction is a chemical reaction that occurs when a substance combines with oxygen, releasing energy in the form of light and heat. An example is the burning of methane: 2 CH₄ + 4 O₂ → 2 CO₂ + 4 H₂O.

Front

What does the chemical formula H₂O represent?

Back

The chemical formula H₂O indicates that each water molecule contains two hydrogen atoms and one oxygen atom.

Front

What happens to the speed of molecules when a substance changes from a gas to a liquid?

Back

The speed of the molecules decreases, because they have lower kinetic energy in the liquid state.

Front

What is nuclear fusion?

Back

Nuclear fusion is the process by which two nuclei join together to form a single nucleus with a larger mass, releasing energy.

Front

What does the law of conservation of mass state?

Back

The law of conservation of mass states that mass cannot be created or destroyed in a chemical reaction. The total mass of the products equals the total mass of the reactants.

Front

What is the difference between nuclear fission and nuclear fusion?

Back

Nuclear fission is the splitting of a large nucleus into smaller nuclei, while nuclear fusion is the combining of small nuclei to form a larger nucleus.

Front

What is kinetic energy?

Back

Kinetic energy is the energy of an object due to its motion. The faster an object moves, the more kinetic energy it has.

Front

What is a chemical reaction?

Back

A chemical reaction is a process that leads to the transformation of one set of chemical substances to another, involving the breaking and forming of bonds.

Front

What is the significance of balancing chemical equations?

Back

Balancing chemical equations ensures that the law of conservation of mass is followed, meaning the number of atoms of each element is the same on both sides of the equation.

Front

What is the role of oxygen in combustion reactions?

Back

Oxygen acts as a reactant in combustion reactions, combining with the fuel to produce carbon dioxide, water, and energy.