Chemical reactions

A substance that is formed as the result of a chemical reaction is a __________________

• Product

• Reactant

• Starters

• Enders

Which of the following is an example of a chemical change?

• water freezes to form ice

• sugar dissolves in water

• gasoline burns in a car engine

• a piece of metal expands when it is heated

Which one shows that a chemical reaction has occurred?

• dissolving

• melting

• formation of a gas

• bending

What type of change occurs when a new substance is formed that has different properties from the original substances?

• chemical change
• nuclear change
• physical change
• mutation

According to the law of conservation of mass, matter cannot be created or ________

True or False: In a complete chemical equation, there must be the same number of atoms of each element on the reactants and products side.

• True

• False

In a chemical reaction, atoms ________ and form new bonds.

Look at the chemical equation.

How many atoms of mercury (Hg) are in the reactants?

Look at the chemical equation.

How many atoms of oxygen (O) are in the reactants?

What is the activation energy?

• The energy of the products
• The energy of the reactants
• The minimum energy needed by the reactants to form the products.
• The energy lost in the reaction