Thermochemistry

To convert from Celsius to Kelvin, you should

• Add 273 to the Celsius temp

• Subtract 273 from the Celsius temp

• Add 273 to the Kelvin temp

• Subtract 273 from the Kelvin temp

Answer explanation

How does specific heat affect how quickly something heats up or cools down?

• High specific heat means it heats up slowly but cools down quickly

• High specific heat means it heat up quickly but cools down slowly

• Low specific heat means it is slow to heat up and cool down

• High specific heat means it is slow to heat up and cool down

Answer explanation

What type of reaction is this?

• Endothermic - the reactants have a lot of energy

• Endothermic - the reactants gained energy before the reaction

• Exothermic - the products have less energy than the reactants

• Exothermic - the reaction had to gain activation energy

Answer explanation

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-4

How much energy is given off when 150 g of water freezes at 0 degrees C?

• 50,100 J

• 627.6 J

• 339,000 J

• 0 J

• 313.5 J

Answer explanation

Q = m* Hf

m = mass

Hf = heat of fusion

Take the mass given in the problem and multiply it by the heat of fusion shown in the attached picture

Tags

NGSS.HS-PS3-1

NGSS.HS-PS3-4

What does a catalyst do?

• lowers activation energy

• increase activation energy

• lowers the energy of reactants

• increases the energy of products

Answer explanation

If you cool steam at 100 degrees C until it freezes into ice at 0 degrees, how many of the following do you need in order to solve the problem?

• Heat of fusion

• Heat of vaporization

• Specific Heat of water

• Specific Heat of ice

• Specific Heat of Steam

Answer explanation

1. 1. The steam starts at 100 degrees C. You need to use the heat of vaporization to figure out the energy removed to condense all of the steam into liquid water.

2. 2. You need the specific heat of water to calculate the energy removed to cool the water down to 0 degrees C.

3. 3. Now that the water is 0 degrees, we need to use the heat of fusion to calculate the energy removed to freeze the water into ice.

4. 4. We do not need the specific heat of ice or steam because the problem doesn't state that the ice or the steam are changing temperature.

Tags

NGSS.HS-PS3-1

NGSS.HS-PS3-4

Temperature is a measure of a substance's ___

• Potential energy

• Kinetic energy

• bond energy

• activation energy

Answer explanation

Tags

NGSS.HS-PS1-5

NGSS.HS-PS3-2

NGSS.HS-PS3-4

Which of the following shows a reaction with a catalyst?

• The dotted line because the activation energy is higher

• The solid line because the activation energy is lower

• The solid line because the catalyzed reactions is always shown with a solid line

• The dotted line because the catalyzed reactions is always shown with a dotted line

• The dotted line because it has a larger delta E

Answer explanation

Tags

NGSS.HS-PS1-4

What is the activation energy of the CATALYZED reaction?

• 1

• 2

• 4

• 5

• 6

Answer explanation

During the solid lines, the energy that is being added is being used to ​ ​ (a)   . During the dashed lines, the energy that is being added is being used to ​ (b)   In the areas with the solid lines, the temperature is ​ ​ (c)   while in the areas with the dashed lines the temperature is ​ (d)  

• break bonds.
• make molecules move faster
• changing
• stable

Tags

NGSS.HS-PS1-4

NGSS.HS-PS1-5

NGSS.HS-PS3-4