Heat is taken in when ammonium nitrate dissolves in water. This is an example of? [et-1]
electrolysis
endothermic charge
exothermic change
thermal decomposition
Change 1. When calcium carbonate forms calcium oxide and carbon dioxide heat is absorbed. Change 2. Calcium oxide releases heat when shaken with carbon dioxide. Which line BEST describes these changes? [et-2]
change 1 is endothermic; change 2 is exothermic
change 1 is exothermic; change 2 is endothermic
change 1 is exothermic; change 2 is exothermic
change 1 is endothermic; change 2 is endothermic
When sodium hydroxide dissolves in water the temperature rises. This is an example of? [et-3]
electrolysis
endothermic charge
exothermic change
thermal decomposition
The breaking of bonds in a chlorine molecule must be? [et-4]
electrolytic
endothermic
equilibrium
exothermic
The making of bonds in forming a hydrogen molecule from hydrogen atoms must be? [et-5]
electrolytic
endothermic
equilibrium
exothermic
Change 1. Water is added to blue cobalt chloride, it turns pink and heats up. Change 2. When pink cobalt chloride is heated, water is driven off, it turns blue and takes in heat. Which line BEST describes these changes? [et-12]
change 1 is endothermic; change 2 is endothermic
change 1 is exothermic; change 2 is exothermic
change 1 is exothermic; change 2 is endothermic
change 1 is endothermic; change 2 is exothermic
Which of the following statements BEST explains why a chemical reaction involving a catalyst goes faster than without the catalyst? [et-22]
the catalyst decreases the energy of collisions between reactant particles
the catalyst increases the frequency of collisions between reactant particles
the catalyst decreases the activation energy for the reaction
the catalyst increases the activation energy for the reaction
Which of the following statements BEST explains why a chemical reaction goes slower without a suitable catalyst? [et-23]
the catalyst increases the energy of collisions between reactant particles
the catalyst increases the frequency of collisions between reactant particles
the activation energy is higher for the catalysed reaction
the activation energy is higher for the uncatalysed reaction
When ammonium chloride dissolves in water the temperature falls. The type of energy change is described as? [et-24]
a decomposition
endothermic
exothermic
activated
When magnesium dissolves in hydrochloric acid the temperature rises. The type of energy change is described as? [et-25]
a decomposition
endothermic
exothermic
activated
The reaction between
sulfuric acid and zinc is exothermic. During the reaction, which observation is correct? [et-26]
a precipitate forms
the temperature of the solution decreases
the temperature of the solution does not change
the temperature of the solution rises
Which of these processes is always exothermic? [et-27]
burning
evaporation
insulation
melting
Which of these processes is always exothermic? [et-28]
combustion
evaporation
insulation
melting
Which of these process is always endothermic? [et-29]
burning
condensation
evaporation
freezing
Which of these process is always endothermic? [et-30]
burning
condensation
freezing
melting
Which of these process is always endothermic? [et-31]
burning
boiling
condensation
freezing
Which of these process is always exothermic? [et-32]
boiling
condensing
evaporation
melting
Which of these process is always exothermic? [et-33]
boiling
evaporating
freezing
melting
The chemical change when a fuel burns can be described as? [et-34]
an endothermic reaction
an exothermic reaction
a precipitation
a reversible reaction
When ammonium nitrate is added to water, an endothermic reaction occurs and? [et-35]
heat is given out
the surroundings get hotter
the temperature falls
the temperature rises
Equal amounts of four different substances (A-D) where added separately to equal amounts of an acid and a thermometer placed in the mixture. For which substance is the reaction the most exothermic? [et-36]
temperature rises by 3oC
temperature rises by 5oC
temperature falls by 3oC
temperature falls by 5oC
Equal amounts of four different substances (A-D) where added separately to equal amounts of an acid and a thermometer placed in the mixture. For which substance is the reaction the most endothermic? [et-37]
temperature rises by 3oC
temperature rises by 5oC
temperature falls by 3oC
temperature falls by 5oC
Equal amounts of four different substances (A-D) where added separately to equal amounts of an acid and a thermometer placed in the mixture. For which substance is the reaction the least exothermic? [et-38]
temperature rises by 3oC
temperature rises by 5oC
temperature falls by 3oC
temperature falls by 5oC
Equal amounts of four different substances (A-D) where added separately to equal amounts of an acid and a thermometer placed in the mixture. For which substance is the reaction the least endothermic? [et-39]
temperature rises by 3oC
temperature rises by 5oC
temperature falls by 3oC
temperature falls by 5oC
Which of the following energy changes corresponds to the activation energy required for the forward reaction to take place? [et-40]
energy change 1
energy change 2
energy change 3
energy change 4
Which of the following energy changes corresponds to the overall energy change for the reaction? [et-42]
energy change 1
energy change 2
energy change 3
energy change 4
Which of the following energy changes corresponds to the activation energy required for the forward reaction to take place? [et-43]
energy change 1
energy change 2
energy change 3
energy change 4
Which of the following energy changes corresponds to the overall energy change for the reaction? [et-45]
energy change 1
energy change 2
energy change 3
energy change 4
When an exothermic reaction takes place, the reaction mixture gets hotter because? [et-46]
energy is always released in a chemical change which makes new substances
exothermic changes always produce gases
in an exothermic change the products are less stable than the reactants
more energy is released when new bonds are made than is needed to break existing bonds
When an exothermic reaction takes place, the reaction mixture gets hotter because? [et-47]
energy is always released in a chemical change which makes new substances
exothermic changes always produce gases
in an exothermic change the products are more stable than the reactants
more energy is absorbed when new bonds are made than is needed to break existing bonds
When an endothermic reaction takes place, the reaction mixture takes in heat because? [et-48]
energy is always absorbed in a chemical change which makes new substances
endothermic changes always produce energy
in an endothermic change the products are more stable than the reactants
more energy is absorbed when existing bonds are broken than is given out when new bonds are formed in the products
When an endothermic reaction takes place, the reaction mixture takes in heat because? [et-49]
energy is always absorbed in a chemical change which makes new substances
endothermic changes always produce energy
in an endothermic change the products are less stable than the reactants
more energy is released when new bonds are formed than is taken in when existing bonds in the reactants are broken
Energy is needed to make a mixture of methane and oxygen react. The mixture explodes when a lighted splint is applied. What type of energy is supplied by the splint? [et-50]
Activation energy
Catalyst energy
Kinetic energy
Renewable energy
Which of these involves a chemical reaction? [et-82] 1. baking bread : 2. boiling water : 3. corroding metals
1 and 2
1 and 3
2 and 3
All of them
Which of the following is a chemical change? [et-83]
cooling a cup of tea
dissolving sugar in coffee
lighting a match
melting an ice-cube
Which of the following is a physical change? [et-84]
dissolving sugar in coffee
lighting a match
making lime from limestone
making polythene from gaseous oil molecules
Which of the following involves a chemical reaction? [et-85]
cooking a cake
filtering sand from water
fractionally distilling oil
melting ice
Which of the following results in a chemical reaction? [et-86]
adding vinegar to water
leaving milk to go sour
mixing salt with water
stirring sugar with tea
Which of these involves a chemical reaction? [et-87]
apples decaying
ice melting
magnetising iron
boiling water
Which of these involves a physical change and NOT a chemical reaction? [et-88]
apples decaying
frying bacon
iron rusting
boiling water
Which of these involves a physical change and NOT a chemical reaction? [et-89]
apples decaying
frying bacon
iron rusting
freezing water
Which of these involves a chemical reaction? [et-90]
crushing apples
toasting bread
magnetising iron
freezing water
Which of these results in chemical change? [et-91]
adding lime to vinegar
adding milk to tea
mixing salt with water
mixing iron and
sulfur powders
Which of these results ONLY in a physical change? [et-92]
adding lime to vinegar
leaving bread to go mouldy
mixing salt with water
adding magnesium to hydrochloric acid
Which of the following temperature changes is NOT the result of a chemical change? [et-93]
a fall in temperature as liquid metal cools to solidify
a fall in temperature as a precipitate falls
a rise in temperature as neutralisation takes place
a rise in temperature when a fuel burns
The reaction between hydrogen and chlorine to form hydrogen chloride can be written as: H2(g) + Cl2(g) ===> 2HCl(g) Use the bond energies shown to calculate the energy change that takes place when hydrogen chloride is formed according to the above equation. (Bond energies in kJ/mol: H-H 435, Cl-Cl 245, H-Cl 430) [et-6]
90 kJ given out
180 kJ given out
125 kJ taken in
250 kJ taken in
The reaction between hydrogen and fluorine to form hydrogen fluoride can be written as H2(g) + F2(g) ===> 2HF(g) Use the bond energies shown to calculate the energy change that takes place when hydrogen fluoride is formed according to the above equation. (Bond energies in kJ/mol: H-H 435, F-F 155, H-F 560) [et-7]
15 kJ taken in
30 kJ taken in
265 kJ given out
530 kJ given out
The diagram below shows the reaction profile for the course of a chemical reaction. Which of the following statements is TRUE? [et-8]
The reaction is exothermic with an activation energy of 130 kJ/mol
The reaction is exothermic and 460 kJ/mol of heat energy is given out
The reaction is endothermic with an activation energy of 970 kJ/mol
The reaction is endothermic with 460 kJ/mol of heat taken in
The diagram below shows the reaction profile for the course of a chemical reaction. Which of the following statements is TRUE? [et-9]
The reaction is exothermic with an activation energy of 970 kJ/mol
The reaction is exothermic and 380 kJ/mol of heat energy is given out
The reaction is endothermic with an activation energy of 970 kJ/mol
The reaction is endothermic with 460 kJ/mol of heat taken in
The diagram below shows the reaction profile for the course of a chemical reaction. Which of the following statements is TRUE? [et-10]
The reaction is exothermic with an activation energy of 860 kJ/mol
The reaction is exothermic and 380 kJ/mol of heat energy is given out
The reaction is endothermic with an activation energy of 310 kJ/mol
The reaction is endothermic with 460 kJ/mol of heat taken in
The diagram below shows the reaction profile for the course of a chemical reaction. Which of the following statements is true? [et-11]
The reaction is exothermic with an activation energy of 860 kJ/mol
The reaction is exothermic and 770 kJ/mol of heat energy is given out
The reaction is endothermic with an activation energy of 860 kJ/mol
The reaction is endothermic with 220 kJ/mol of heat taken in
The chemical equation shows how water is formed from its elements. 2H2 + O2 ==> 2H2O The bond energies in kJ/mol are: H-H 440; O=O 500; H-O 460 How much energy is released when two moles of water are formed? [et-13]
460 kJ
480 kJ
920 kJ
2300 kJ
The reaction between hydrogen and bromine to form hydrogen bromide can be written as H2(g) + Br2(g) ===> 2HBr(g) Use the bond energies shown to calculate the energy change that takes place when hydrogen bromide is formed according to the above equation. (Bond energies in kJ/mol: H-H 435; Br-Br 200; H-Br 370) [et-14]
105 kJ given out
105 kJ taken in
270 kJ given out
270 kJ taken in
Which of the following reaction profiles represents an exothermic reaction with no activation energy? [et-15]
Which of the following reaction profiles represents an endothermic reaction with no activation energy? [et-16]
Which of the following reaction profiles represents a reaction with an activation energy but with no overall energy change? [et-17]
Which of the following reaction profiles represents an exothermic reaction with a small activation energy? [et-18]
Which of the following reaction profiles represents an endothermic reaction with a large activation energy? [et-19]
Which of the following reaction profiles represents an exothermic reaction with a large activation energy? [et-20]
Which of the following reaction profiles represents an endothermic reaction with a small activation energy? [et-21]
Which of the following energy changes corresponds to the activation energy required for the
reverse or backward reaction to take place? [et-41]
energy change 1
energy change 2
energy change 3
energy change 4
Which of the following energy changes corresponds to the activation energy required for the reverse or backward reaction to take place? [et-44]
energy change 1
energy change 2
energy change 3
energy change 4
An energy level diagram can be used to show the energy changes involved in the course of a chemical reaction. The reaction must be? [et-51]
an exothermic reaction
a thermal decomposition
an endothermic reaction
a reaction with zero activation energy
An energy level diagram can be used to show the energy changes involved in the course of a chemical reaction. The reaction must be? [et-52]
a combustion reaction
a thermal decomposition
an endothermic reaction
a reaction with zero activation energy
An energy level diagram can be used to show the energy changes involved in the course of a chemical reaction. The reaction must be? [et-53]
an exothermic reaction
a combustion reaction
an endothermic reaction
a reaction with zero activation energy
The diagram shows the energy changes during a reaction. What would occur if a catalyst was used?[et-54]
energy change 1 is lowered
energy change 2 is raised
energy change 3 is lowered
energy change 4 is raised
The diagram shows the energy changes during a reaction. What would occur if a catalyst was used?[et-55]
energy change 1 is lowered
energy change 2 is raised
energy change 3 is lowered
energy change 4 is raised
The
diagram shows the profile of the energy changes for a reaction. Which energy change is reduced by using a suitable catalyst? [et-56]
energy change 1
energy change 2
energy change 3
energy change 4
The
diagram shows the profile of the energy changes for a reaction. Which energy change is reduced by using a suitable catalyst? [et-57]
energy change 1
energy change 2
energy change 3
energy change 4
The
diagram shows the profile of the energy changes for a reaction. Which energy change represents the energy needed to break chemical bonds so that new products can form? [et-58]
energy change 1
energy change 2
energy change 3
energy change 4
The
diagram shows the profile of the energy changes for a reaction. Which energy change represents the energy needed to break chemical bonds so that new products can form? [et-59]
energy change 1
energy change 2
energy change 3
energy change 4
For the reaction: 3H2 + N2 ==> 2NH3 The breaking of bonds in a hydrogen molecule when it combines with nitrogen to form ammonia must be? [et-60]
electrolytic
electrostatic
endothermic
exothermic
For the reaction: 3H2 + N2 ==> 2NH3 The breaking of bonds in a nitrogen molecule when it combines with hydrogen to form ammonia must be? [et-61]
electrolytic
electrostatic
endothermic
exothermic
For the reaction: 3H2 + N2 ==> 2NH3 The forming of bonds in an ammonia molecule when hydrogen combines with nitrogen must be? [et-62]
electrolytic
electrostatic
endothermic
exothermic
The equation for the formation of ammonia from its elements is: 3H2 + N2 ==> 2NH3 Given the BOND ENERGIES in kJ/mol for H-H = 440; N-N = 940; N-H = 390, calculate the energy released when 2 moles of ammonia are formed. [et-63]
80 kJ
90 kJ
990 kJ
1110 kJ
The reaction between hydrogen and iodine to form hydrogen iodide can be written as H2(g) + I2(g) ===> 2HI(g) Use the bond energies shown to calculate the energy change that takes place when hydrogen iodide is formed according to the above equation. (Bond energies in kJ/mol: H-H 440, I-I 150, H-I 300) [et-64]
10 kJ given out
10 kJ taken in
600 kJ given out
590 kJ taken in
When hydrogen fluoride is heated it breaks down into hydrogen and fluorine. The equation can be written as: 2HF(g) ==> H2(g) + F2(g) Use the bond energies shown below to calculate the energy change that takes place when 2 moles of hydrogen fluoride thermally decomposes in this way. (bond energies in kJ/mol: H-H = 440; F-F = 155; H-F = 560) [et-65]
525 kJ taken in
525 kJ given out
560 kJ given out
560 kJ taken in
When hydrogen chloride is heated it breaks down into hydrogen and fluorine. The equation can be written as: 2HCl(g) ==> H2(g) + Cl2(g) Use the bond energies shown below to calculate the energy change that takes place when 2 moles of hydrogen chloride thermally decomposes in this way. (bond energies in kJ/mol: H-H = 440; Cl-Cl = 245; H-Cl = 430) [et-66]
175 kJ given out
175 kJ taken in
860 kJ given out
685 kJ taken in
When hydrogen bromide is heated it breaks down into hydrogen and bromine. The equation can be written as: 2HBr(g) ==> H2(g) + Br2(g) Use the bond energies shown below to calculate the energy change that takes place when 2 moles of hydrogen bromide thermally decomposes in this way. (bond energies in kJ/mol: H-H = 440; Br-Br = 200; H-Br = 370) [et-67]
740 kJ given out
640 kJ taken in
100 kJ taken in
100 kJ given out
When hydrogen iodide is heated it breaks down into hydrogen and iodine. The equation can be written as: 2HI(g) ==> H2(g) + I2(g) Use the bond energies shown below to calculate the energy change that takes place when 2 moles of hydrogen iodide thermally decomposes in this way. (bond energies in kJ/mol: H-H = 440; I-I = 150; H-I = 300) [et-68]
600 kJ given out
600 kJ taken in
10 kJ given out
10 kJ taken in
Methane molecules, CH4, can be broken down into gaseous carbon and hydrogen atoms. The energy needed to break the bonds to do this is 1664 kJ/mol. Therefore the average C-H bond energy in the molecule is? [et-69]
416 kJ
832 kJ
1664 kJ
6656 kJ
Ammonia molecules, NH3, can be broken down into gaseous nitrogen and hydrogen atoms. The energy needed to break the bonds to do this is 1164 kJ/mol. Therefore the average N-H bond energy in the molecule is? [et-70]
388 kJ
582 kJ
1164 kJ
291 kJ
Water molecules, H2O, can be broken down into gaseous oxygen and hydrogen atoms. The energy needed to break the bonds to do this is 928 kJ/mol. Therefore the average O-H bond energy in the molecule is? [et-71]
116 kJ
232 kJ
464 kJ
928 kJ
The diagram shows the energy changes as a reaction proceeds. For a reaction to be exothermic which of the following must be positive? [et-72]
Y + X - W
Y - X + W
W - Y
X - Y
The diagram shows the energy changes as a reaction proceeds. Which of the following is the activation energy? [et-73]
W - X
W + X - Y
W - Y
X - Y
The diagram shows the energy changes as a reaction proceeds. Which of the following is the overall energy change? [et-74]
W - X given out
W - X taken in
X - Y given out
X - Y taken in
The diagram shows the energy changes as a reaction proceeds. For a reaction to be endothermic which of the following must be positive? [et-75]
W - X
X - Y
W + X - Y
W - Y
The diagram shows the energy changes as a reaction proceeds. Which of the following is the activation energy? [et-76]
Y + X - W
Y - X + W
X - Y
W - Y
The diagram shows the energy changes as a reaction proceeds. Which of the following is the overall energy change? [et-77]
X - Y given out
W - Y taken in
X - Y given out
X - Y taken in
Sodium hydroxide and dilute hydrochloric acid react together to form sodium chloride without being heated. This is because the? [et-78]
the activation energy is high
the activation energy is low
the activation energy is zero
the reaction is exothermic
Natural gas and the oxygen in air will only react when heated. This is because the reaction? [et-79]
has a zero activation energy
has a low activation energy
is exothermic
has a high activation energy
The diagram shows the energy changes as a reaction proceeds. If a suitable catalyst is used, which of the following energy changes occurs? [et-80]
W - X is increased
W - X is reduced
X - Y is increased
X - Y is reduced
The diagram shows the energy changes as a reaction proceeds. If a suitable catalyst is used, which of the following energy changes occurs? [et-81]
W - X is increased
W - X is reduced
X - Y is increased
X - Y is reduced
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chemistry examination?
Heat is taken in when ammonium nitrate dissolves in water. This is an example of? [et-1]
The reaction between
sulfuric acid and zinc is exothermic. During the reaction, which observation is correct? [et-26]
Which of these process is always exothermic? [et-32]
Equal amounts of four different substances (A-D) where added separately to equal amounts of an acid and a thermometer placed in the mixture. For which substance is the reaction the least endothermic? [et-39]
Which of the following energy changes corresponds to the activation energy required for the forward reaction to take place? [et-40]
Which of the following energy changes corresponds to the activation energy required for the forward reaction to take place? [et-43]
When an exothermic reaction takes place, the reaction mixture gets hotter because? [et-46]
The diagram below shows the reaction profile for the course of a chemical reaction. Which of the following statements is TRUE? [et-8]
The diagram below shows the reaction profile for the course of a chemical reaction. Which of the following statements is TRUE? [et-10]
An energy level diagram can be used to show the energy changes involved in the course of a chemical reaction. The reaction must be? [et-51]
An energy level diagram can be used to show the energy changes involved in the course of a chemical reaction. The reaction must be? [et-53]
The diagram shows the energy changes as a reaction proceeds. For a reaction to be exothermic which of the following must be positive? [et-72]
The diagram shows the energy changes as a reaction proceeds. For a reaction to be endothermic which of the following must be positive? [et-75]
