Deck 8: Energy

Question 1

How much heat is required to raise the temperature of 125 grams of water by 10.0 °C?

A) 1,250 J
B) 12.5 J
C) 10.0 J
D) 5,230 J

Answer 1

5,230 J

Question 2

Which process is exothermic?

A) melting
B) boiling
C) evaporating
D) All of these processes are exothermic.
E) None of these processes is exothermic.

Answer 2

None of these processes is exothermic.

Question 3

The label on a York Peppermint Patty^® lists 140 Calories (kcal)of stored chemical energy.What is this energy in kilojoules?

A) 0.033
B) 33
C) 590
D) 0.030

Answer 3

590

Question 4

The mixture of gas and air inside a cylinder reacts,releasing 400 kJ of total energy.If the system does 250 kJ of work on the piston,how much energy is released as HEAT?

A) 150 kJ
B) 1.60 kJ
C) 650 kJ
D) 0.63 kJ

Question 5

The label on a two-pack of Reese's Peanut Butter^® cups lists 260 Calories (kcal)of stored chemical energy.What is this energy in kilojoules?

A) 0.062
B) 62
C) 1,100
D) 0.016

Question 6

How much heat is required to raise the temperature of 85.0 grams of water by 15.0 °C?

A) 1,280 J
B) 5.67 J
C) 15.0 J
D) 5,330 J

Question 7

Which process is endothermic?

A) melting
B) boiling
C) evaporating
D) All of these processes are endothermic.
E) None of these processes is endothermic.

Question 8

Chemists measure heat changes in reactions using a technique called:

A) spectrometry.
B) thermopylae.
C) thermolysis.
D) calorimetry.

Question 9

The signs of q and w for gasoline burning are,respectively:

A) negative and negative.
B) positive and positive.
C) positive and negative.
D) negative and positive.

Question 10

Changes in energy can take place in what two forms?

A) potential and kinetic energy
B) heat and work
C) heat and temperature
D) thermofission and nucleosis

Question 11

A sample of ammonium chloride dissolves in water,absorbing heat from the surrounding water and causing the temperature to drop by 15 °C.If the heat change for the reaction is +200 J,what is the heat change for the surrounding water?

A) 3,000 J·°C
B) + 15 °C
C) +200 J
D) -200 J

Question 12

A small Oreo Dairy Queen^® blizzard contains 550 kilocalories of stored chemical energy.What is this energy in kilojoules?

A) 0.130
B) 130
C) 2,300
D) 0.0076

Question 13

A sample of sodium hydroxide dissolves in water,releasing heat to the surrounding water and causing the temperature to rise by 20 °C.If the heat change for the reaction is -300 J,what is the heat change for the surrounding water?

A) 6,000 J·°C
B) - 20 °C
C) -300 J
D) +300 J

Question 14

Which reaction represents the melting of ice?

A) H₂O (s) $\rightarrow$ H₂O (l)+ energy
B) energy + H₂O (s) $\rightarrow$ H₂O (l)
C) H₂O (l) $\rightarrow$ H₂O (s)+ energy
D) energy + H₂O (l) $\rightarrow$ H₂O (s)

Question 15

How much heat is released when 35.0 g of water are cooled by 40.0 °C?

A) 1.40 × 10³ J
B) 0.875 J
C) 40.0 J
D) 5,860 J

Question 16

Energy is often stored in the form of chemical bonds.This is a type of _____ energy.

A) kinetic
B) heat
C) potential

Question 17

Which reaction represents the freezing of water?

A) H₂O (s) $\rightarrow$ H₂O (l)+ energy
B) energy + H₂O (s) $\rightarrow$ H₂O (l)
C) H₂O (l) $\rightarrow$ H₂O (s)+ energy
D) energy + H₂O (l) $\rightarrow$ H₂O (s)

Question 18

A sample of ammonium chloride dissolves in water,absorbing heat from the surrounding water and causing the temperature to drop by 20 °C.If the heat change for the reaction is +300 J,what is the heat change for the surrounding water?

A) 6,000 J·°C
B) + 20 °C
C) +300 J
D) -300 J

Question 19

The mixture of gas and air inside a cylinder reacts,releasing 300 kJ of heat.If the system does 150 kJ of work on the piston,what is the change in total energy?

A) 450 kJ
B) -450 kJ
C) 150 kJ
D) -150 kJ

Question 20

The law of conservation of energy states that,in chemical and physical changes:

A) energy is neither created nor destroyed.
B) energy is always released to the surroundings.
C) exothermic changes are favored.
D) the universe increases the amount of energy.

Question 21

The following reaction is an example of an _____ reaction. 2 N₂ (g)+ O₂ (g) $\rightarrow$ 2 N₂O (g) $\Delta$ H_rxn = +163.2 kJ

A) exothermic
B) endothermic
C) endergonic
D) ergonomic

Question 22

The fuel value of propane is 50.3 kJ/g.If a full barbecue grill tank holds 9.0 kg,how much heat results from the complete combustion of all the propane? (Watch your units!)

A) 5.58 kJ
B) 453,000 kJ
C) 5,580 kJ
D) 453 kJ

Question 23

The following reaction is an example of an _____ reaction. 2 K (s)+ Cl₂ (g) $\rightarrow$ 2 KCl (g) $\Delta$ H_rxn = -873.0 kJ

A) exothermic
B) endothermic
C) endergonic
D) ergonomic

Question 24

If the reaction below produces 5,230 kJ of energy,how many grams of KCl will be produced? (KCl = 74.6 g/mol) 2 K (s)+ Cl₂ (g) $\rightarrow$ 2 KCl (g) $\Delta$ H_rxn = -873.0 kJ

A) 894 g
B) 447 g
C) 5.99 g
D) 6.12 × 10⁴ g

Question 25

The dissolving of sodium acetate (NaC₂H₃O₂ = 82.04 g/mol)in water can be described by the following reaction: NaC₂H₃O₂ (s) $\rightarrow$ NaC₂H₃O₂ (aq) $\Delta$ H = -17.2 kJ
How much heat will be released when 125 g of sodium acetate dissolve in water?

A) 26.2 kJ
B) 2,150 kJ
C) 7.26 kJ
D) 11.3 kJ

Question 26

Water has a relatively high specific heat compared to metals.If a 20-g piece of a nonreactive metal at 80 °C is dropped into 20 g of cool water at 20 °C,what will be the final temperature of water and metal together?

A) 50 °C
B) somewhere between 20 °C and 50 °C
C) somewhere between 50 °C and 80 °C
D) 100 °C

Question 27

What is the specific heat of tin if a 55.0-g sample absorbs 982 J of heat to raise its temperature by 85.0 °C?

A) 0.210 J/g °C
B) 4.59 × 10⁶ J/g °C
C) 4.76 J/g °C
D) 85.0 J/g °C

Question 28

The dissolving of ammonium nitrate (NH₄NO₃ = 80.06 g/mol)in water can be described by the following reaction: NH₄NO₃ (s) $\rightarrow$ NH₄NO₃ (aq) $\Delta$ H = +25.4 kJ
How much heat will be absorbed when 175 g of sodium acetate dissolve in water?

A) 55.5 kJ
B) 4,450 kJ
C) 6.89 kJ
D) 11.6 kJ

Question 29

A bomb calorimeter has a heat capacity of 25.6 kJ/°C.How much will the temperature of the calorimeter rise if it absorbs 455 kJ of heat energy?

A) 0.0563 °C
B) 25.6 °C
C) 17.8 °C
D) 1.16 × 10⁴ °C

Question 30

The fuel value of natural gas is 54.0 kJ/g.How much heat results from the combustion of 2.84 kg of natural gas? (Watch your units!)

A) 19.0 kJ
B) 153,000 kJ
C) 1,900 kJ
D) 153 kJ

Question 31

Consider the following reaction.How much heat is absorbed if 5.00 moles of nitrogen react with excess oxygen? 2 N₂ (g)+ O₂ (g) $\rightarrow$ 2 N₂O (g) $\Delta$ H_rxn = +163.2 kJ

A) 32.6 kJ
B) 0.0613 kJ
C) 816 kJ
D) 408 kJ

Question 32

When a liquid evaporates,it absorbs heat from its surroundings.This is a(n)_____ process.

A) endothermic
B) exothermic
C) thermoneutral
D) exergetic

Question 33

When a gas condenses,it releases heat to its surroundings.This is a(n)_____ process.

A) endothermic
B) exothermic
C) thermoneutral
D) exergetic

Question 34

When a metal object is dropped into cold water,it releases 4,715 J of energy to its surroundings,and its temperature decreases from 100.0 °C to 20.0 °C.The mass of the object is 420 grams.What is the specific heat of this material?

A) 0.561 J/g·°C
B) 1.58 × 10⁸ J/g·°C
C) 0.140 J/g·°C
D) 7.14 J/g·°C

Question 35

An industrial reactor has a heat capacity of 33,400 kJ/°C.How much will the temperature of the reactor rise if it absorbs 3.00 × 10⁵ kJ of heat energy?

A) 0.11 °C
B) 22.2 °C
C) 8.98 °C
D) 1.00 × 10¹⁰ °C

Question 36

Consider the following reaction.How much heat is released if 5.00 moles of potassium react with excess chlorine? 2 K (s)+ Cl₂ (g) $\rightarrow$ 2 KCl (g) $\Delta$ H_rxn = -873.0 kJ

A) 175 kJ
B) 0.0115 kJ
C) 4,370 kJ
D) 2,180 kJ

Question 37

What is the specific heat of copper if a 55.0-g sample absorbs 1,590 J of heat to raise its temperature by 75.0 °C?

A) 0.385 J/g °C
B) 6.56 × 10⁶ J/g °C
C) 2.59 J/g °C
D) 75.0 J/g °C

Question 38

The fuel value of propane is 50.3 kJ/g.How much heat results from the combustion of 2.84 kg of propane? (Watch your units!)

A) 17.7 kJ
B) 143,000 kJ
C) 17,700 kJ
D) 143 kJ

Question 39

If the reaction below absorbs 1,350 kJ of energy,how many grams of N₂O will be produced? (N₂O = 44.0 g/mol) 2 N₂ (g)+ O₂ (g) $\rightarrow$ 2 N₂O (g) $\Delta$ H_rxn = +163.2 kJ

A) 728 g
B) 364 g
C) 8.27 g
D) 5.01 × 10³ g