Warm-Ups Day 6

Which of the following phase changes is an example of an endothermic process?

• Freezing

• Condensation

• Melting

• Deposition

Answer explanation

Melting is an endothermic process because it requires the absorption of heat to convert a solid into a liquid. In contrast, freezing, condensation, and deposition release heat, making them exothermic processes.

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-4

What happens to the temperature of a substance during a phase change from liquid to gas?

• It increases

• It decreases

• It remains constant

• It fluctuates

Answer explanation

During a phase change from liquid to gas, the temperature of the substance remains constant. This is because the energy added is used to break intermolecular bonds rather than increase temperature.

Tags

NGSS.MS-PS1-4

Which of the following is an example of an exothermic reaction?

• Photosynthesis

• Combustion of wood

• Melting of ice

• Evaporation of water

Answer explanation

The combustion of wood is an exothermic reaction because it releases heat and light energy as it burns. In contrast, photosynthesis, melting of ice, and evaporation of water are endothermic processes that absorb energy.

Tags

NGSS.MS-PS3-3

NGSS.MS-PS3-5

Identify the endothermic reaction from the following options.

• Rusting of iron

• Dissolving ammonium nitrate in water

• Burning of coal

• Freezing of water

Answer explanation

Dissolving ammonium nitrate in water is an endothermic reaction because it absorbs heat from the surroundings, resulting in a temperature drop. In contrast, rusting, burning coal, and freezing water are exothermic or involve heat release.

Tags

NGSS.MS-PS1-4

How does increasing temperature generally affect the rate of an exothermic reaction?

• It decreases the rate

• It has no effect

• It increases the rate

• It stops the reaction

Answer explanation

Increasing temperature generally increases the rate of an exothermic reaction. This is because higher temperatures provide more energy to the reactants, leading to more frequent and effective collisions, thus speeding up the reaction.

Tags

NGSS.HS-PS1-5

Which phase change involves the release of energy?

• Sublimation

• Vaporization

• Condensation

• Melting

Answer explanation

Condensation is the phase change where a gas turns into a liquid, releasing energy in the form of heat. This is the opposite of vaporization, which requires energy input.

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-4

What is the effect of temperature on the solubility of most solids in water?

• Solubility decreases with temperature

• Solubility remains constant

• Solubility increases with temperature

• Solubility fluctuates with temperature

Answer explanation

For most solids, solubility in water increases with temperature. Higher temperatures provide more energy, allowing more solute to dissolve, which is why the correct answer is that solubility increases with temperature.

Tags

NGSS.MS-PS1-4

Which of the following reactions is likely to absorb heat from the surroundings?

• Neutralization of an acid and a base

• Dissolving sodium hydroxide in water

• Photosynthesis in plants

• Combustion of gasoline

Answer explanation

Photosynthesis in plants is an endothermic reaction, meaning it absorbs heat from the surroundings to convert carbon dioxide and water into glucose and oxygen, unlike the other options which release heat.

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-4

During which phase change does a substance absorb energy from its surroundings?

• Freezing

• Deposition

• Condensation

• Sublimation

Answer explanation

During sublimation, a substance transitions from solid to gas, absorbing energy from its surroundings. In contrast, freezing, deposition, and condensation release energy.

Tags

NGSS.MS-PS1-4

What is the primary reason that endothermic reactions feel cold to the touch?

• They release heat to the surroundings

• They absorb heat from the surroundings

• They do not involve any heat exchange

• They produce cold substances

Answer explanation

Endothermic reactions absorb heat from the surroundings, which causes a decrease in temperature in the immediate environment, making them feel cold to the touch.

Tags

NGSS.MS-PS1-4