week 7 practice

A bag of candy has 220 cal. How much energy is in this bag in kJ?

hint: 1 cal = 4.184 joules

• 300 kj

• 5445 kj

• 920 kj

• 4000 kj

For a system that gains thermal energy and does work on its surroundings,

• heat and work are both positive

• heat is positive and work is negative

• heat is negative work is positive

• heat and work are both negative

Calculate the internal energy for a system that does 422 J of work and loses 227 J of energy as heat.

• -649 kJ

• 444 kJ

• -500 kJ

• 234 kJ

A 3.54 g piece of aluminum is heated to 96.2 degrees Celsius and allowed to cool to room temp., 22.5 degrees celsius. Calculate the heat in kJ associated with the cooling process. The specific heat of aluminum is 0.903 J/g.

• -236 kJ

• -0.236 kJ

• 33.3 kJ

• -4.7 kJ

A 1.5 g iron nail is heated to 95 degrees Celsius and placed into a beaker of water. Calculate the heat gained by the water if the final equilibrium temperature is 57.8 degrees celsius. The specific heat capacity of iron is 0.449 J/g and for water it is 4.18 J/g.

• -25 J

• 25 J

• -44 J

• 44 J

How much work is done when a container expands 2.55 L against an external pressure of 1.50 atm?

101.3 J = 1 L atm

• -300 kJ

• -387 J

• 3023 J

• 300 L