Chemical Reactions

The chemical name for sand is silicon dioxide. Select the two elements found in a sample of sand.

• silicon

• oxygen

• sand

• carbon

Which of these processes are chemical reactions?

• boiling an egg

• crushing spices

• vegetables rotting

• chopping vegetables

• dew forming

Which of these are examples of mixing and separating?

• removing seed casings from grains

• a soda bottle bubbling when it is opened

• a bright copper statue turning green from weathering

• removing salt from seawater

• water decomposing to oxygen and hydrogen

The reaction has at least

two reactants and one product.

The reaction has one reactant

and at least two products.

Oxygen is one of the reactants,

and a large amount of energy is

released.

One or more atoms replaces

a part of a compound.

The products are always salt

and water.

Nitrogen (N) and hydrogen (H) react with each other to produce ammonia (NH₃). This reaction is shown in an equation as N₂ + 3H₂ → 2NH₃. What is the ratio of nitrogen atoms to hydrogen atoms in ammonia?

• 1 to 2

• 1 to 3

• 2 to 1

• 2 to 3

Which law represents a balanced chemical equation?

• Avogadro’s hypothesis

• ideal gas law

• law of conservation of mass

• Newton’s first law of motion