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 sulphuric 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 sulphur 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