Q: Which formula is used to calculate the heat absorbed or released by a substance?

$$q = m \times C_s \times \Delta T$$

Q: What is the relationship between the energy lost by the system and the energy gained by the surroundings?

$$\Delta E_{\text{sys}} = -\Delta E_{\text{surr}}$$

Question 1

Which of the following best defines the 'system' in thermodynamics?

Accepted Answer

The part of the universe that is undergoing a change or reaction being studied.

Question 2

If a chemical reaction in a beaker absorbs heat from the surroundings, which of the following statements is correct?

Accepted Answer

The reaction is endothermic and $$q is $$positive.

Question 3

A gas absorbs $$5.973 kJ of $$heat and does $$0.589 kJ of $$work by pushing a piston. What is the change in internal energy ($$\Delta E) of $$the gas?

Accepted Answer

$$\Delta E = 5.384 kJ$$

Question 4

Which equation correctly relates the change in internal energy to heat and work?

Accepted Answer

$$\Delta E = q + w$$

Question 5

A $$10.0 L $$balloon loses $$206 J of $$heat, and its internal energy decreases by $$-452 J. $$What is the value of work ($$w) $$for the system?

Accepted Answer

$$w = -246 J$$

Question 6

Which of the following best describes an exothermic process?

Accepted Answer

The system releases heat and $$q is $$negative.

Question 7

Calculate the work done (in Joules) by inflating a balloon from $$2.0 L to$$ $$3.8 L on $$the moon, where the atmospheric pressure is $$0.00500$$ atm. ($$1.00$$ atm $$\cdot L$$ $$= 101.31 J)$$

Accepted Answer

$$w = -0.91 J$$

Question 8

Which formula is used to calculate the heat absorbed or released by a substance?

Accepted Answer

$$q = m 	imes C_s 	imes \Delta T$$

Question 9

A $$5.009 g $$lump of gold at $$37.0^\circC $$absorbs $$11.04 J of $$heat energy. What is its final temperature? ($$C_{	ext{gold}} = 0.129 J/g$^\circC)$$

Accepted Answer

$$T_f = 54.1^\circC$$

Question 10

Which statement about bomb calorimetry is correct?

Accepted Answer

All energy from the reaction is converted to heat because $$\Delta V = 0.$$

Question 11

What is the relationship between the energy lost by the system and the energy gained by the surroundings?

Accepted Answer

$$\Delta E_{	ext{sys}} = -\Delta E_{	ext{surr}}$$

Question 12

Which of the following is true for an endothermic reaction in a calorimeter?

Accepted Answer

The temperature of the calorimeter decreases.

Question 13

Which equation defines enthalpy ($$H$$)?

Accepted Answer

$$H = E + PV$$

Question 14

A hot piece of iron at $$275.5^\circC is $$placed in $$200 g of $$water at $$22.2^\circC. $$The final temperature is $$28.1^\circC$$. ($$C_{	ext{Fe}} = 0.449 J/g$^\circC$$, $$C_{	ext{H}_2O$$} = 4.184$$ J/g$$^\circ$$C)$. What is the mass of the iron?

Accepted Answer

8.2 g

Question 15

Which of the following is a correct statement about constant pressure calorimetry (coffee cup calorimeter)?

Accepted Answer

The reaction is open to the atmosphere and occurs at constant pressure.

Question 16

For the reaction of one mole of sodium with water, $$367.5 kJ of $$heat is produced and $$2.5 kJ of $$work is done. What are $$\Delta H$$ and $$\Delta E$$ for the reaction?

Accepted Answer

$$\Delta H = -367.5 kJ$$, $$\Delta E = -370.0 kJ$$

Question 17

Which of the following is an extensive property?

Accepted Answer

Enthalpy

Question 18

In a bomb calorimeter, what is the value of $$\Delta V$$?

Accepted Answer

$$\Delta V = 0$$

Question 19

Which of the following best describes the surroundings in a thermodynamic process?

Accepted Answer

Everything in the vicinity of the system except the system itself.

Question 20

Which of the following is the correct conversion factor for $$1.00$$ atm $$\cdot L to $$Joules?

Accepted Answer

$$1.00$$ atm $$\cdot L$$ $$= 101.31 J$$

Chapter 7: Thermochemistry and Thermodynamics Study Notes

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