Thermochemistry

The unit(s) for heat are?

• calories
• joules
• calories or joules

Tags

NGSS.HS-PS3-4

135 g of aluminum (initially at 400^oC) are mixed with an unknown mass of water (initially at 25^oC). When thermal equilibrium is reached, the system has a temperature of 80^oC. Find the mass of the water.

• 197.2g
• 168.6g
• 168.6J
• 23.1g

Tags

NGSS.HS-PS3-1

NGSS.HS-PS3-4

A piece of metal with a mass of 32.8 g is heated to 100.5°C and dropped into 138.2 g of water at 20.0°C.  The final temperature of the system is 30.2°C.  What is the specific heat capacity of the metal?

• 2.56 J/g°C
• 0.391 J/g°C
• 5.29 J/g°C
• 3.50 J/g°C

Tags

NGSS.HS-PS3-1

NGSS.HS-PS3-4

In the lab, an experimenter mixes 75.0 g of water (initially at 30^oC) with 83.8 g of a solid metal (initially at 600^oC). At thermal equilibrium, he measures a final temperature of 50.0^oC. What was the specific heat of the metal?

• 0.672 J/g ⁰C
• 0.533 ⁰C
• 1.156 J/g ⁰C
• 0.133 J/g ⁰C

Tags

NGSS.HS-PS3-4

The specific heat of a substance is the amount of energy needed to raise the temperature of one gram, one degree Celsius of a substance.

• True
• False
• sometimes

As a reaction is taking place,  the student notices that the temperature has dropped. This indicates that the system has increased in energy. What type of process is this?

• Endothermic
• Exothermic

Tags

NGSS.HS-PS1-4

For the formula:
 Q= m c ∆T
The  units for specific heat are:

• g /J C
• J/g⁰C
• kJ/g
• KJ/⁰Cg

Using the heat equation, what would the formula look like if we were solving for change in temperature?

• ΔT c =Qm
• ΔT=Q/mc
• ΔT = Qm/c
• mcQ=∆T

A sample of iron receives 50 J of heat energy that raises the temperature of the iron 25.0°C. If iron has a specific heat of .10 J/g°C, what is the mass of the iron sample?

• 25g
• 20g
• 17g
• 50g

Tags

NGSS.HS-PS3-1

What would be the effect on particles if more heat is supplied to the system?

• They would slow down
• They would stop moving
• They would speed up
• There would be no effect

Tags

NGSS.HS-PS3-2