Energy Changes in Chemical Reactions

Scientists are looking into the decomposition of water (H₂O --> H₂ + H₂O) to make hydrogen fuel with the help of the Sun’s energy. What challenge do scientists face with this task?

• Decomposing water requires a high activation energy.

• The Sun isn't a renewable resource.

• Decomposing water results in toxic byproducts.

Which chemical reaction shows photosynthesis?

• carbon + oxygen → carbon dioxide

• water + carbon dioxide + sunlight → oxygen + glucose

• hydrogen + oxygen → water

Tags

NGSS.HS-LS1-5

NGSS.HS-LS2-5

Which of these reactions is a combustion reaction?

• production of food by plants with the help of the Sun's energy

• rotting of fruits and vegetables

• burning wood

Tags

NGSS.MS-PS1-5

Which sentences describe disadvantages of burning fossil fuels instead of using hydrogen fuel cells?

There are two choices that are correct.

• Burning fossil fuels contributes to climate change.

• Burning fossil fuels takes place inside expensive fuel cells.

• Fossil fuels are nonrenewable.

Tags

NGSS.HS-ESS3-5

In a given chemical reaction, the energy of the products is less than the energy of the reactants. Which statement is true for this chemical reaction?

• Energy is absorbed in the reaction.

• Energy is released in the reaction.

• There is no transfer of energy in the reaction.

Tags

NGSS.HS-PS1-4

A hydrogen fuel cell is more efficient than a combustion reaction because very little of the released energy is released as _________.

• heat

• electrical energy

• chemical energy

Tags

NGSS.HS-PS3-4

When used at home, a fuel cell eliminates the need for ____________ because the cell is portable.

• oxygen

• hydrogen

• an electrical grid

Tags

NGSS.HS-PS3-3

In a chemical reaction, activation energy increases the __________________________of the reactants.

• amount of chemical energy

• number of particles

• temperature

Tags

NGSS.HS-PS1-4

Which of the following reactions RELEASE energy? (gets warm) There are 3 here.

• burning candle

• respiration in cells

• produces electric current

• baking bread

Tags

NGSS.HS-PS1-4

NGSS.HS-LS1-7

Which of the following chemical reactions ABSORBS energy? There are 3 correct answers.

• photosynthesis

• activating a cold pack

• burning a candle

• baking bread

Tags

NGSS.HS-PS1-4