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Worksheetsenergy from chemicals
Total questions: 11
Worksheet time: 11mins
The burning of fuels is an exothermic reaction. what is the meaning of the term exothermic
A gas is produced
Energy is released
Heat is observed
The mass of the fuel decrease
Which statement about the combustion of fuel is correct?
it always produces carbondioxide
it always produces carbonmonooxide
it is always endothermic
it is always exothermic
Which statement about endothermic and exothermic reactions is correct?
In an endothermic reaction, less energy is absorbed in bond breaking than is released in bond forming.
In an endothermic reaction, the activation energy is always higher than in an exothermic reaction.
In an exothermic reaction, more energy is absorbed in bond breaking than is released in bond forming.
In an exothermic reaction, the reactants are higher on an energy level diagram than the products.
Which statement about fuels is correct?
Heat energy is only produced by burning fuels
Hydrogen is used as a fuel although it is difficult to store
Methane is a good fuel because it produces only water when burned.
Uranium is burned in air to produce energy.
Which arrow on the energy level diagram shows the overall energy change for an endothermic reaction?
A
B
C
D
Which row describes an endothermic reaction?
The equation for the complete combustion of methane is shown.
What is the energy change for the reaction?
–818 kJ /mol
–359 kJ /mol
–323 kJ /mol
+102 kJ / mol
Hydrogen fuel cells can be used to power cars. Which statements about a fuel cell are correct?
1 The balanced equation for the reaction is
H2 + O2 ==> H2O.
2 The fuel cell generates electricity.
3 In the fuel cell hydrogen is reduced.
4 The reactants are gases at room temperature.
1 and 2
1 and 3
2 and 4
3 and 4
10 g of ammonium nitrate is added to water at 25 °C and the mixture stirred. The ammonium nitrate dissolves and, after one minute, the temperature of the solution is 10 °C. Which word describes this change?
endothermic
exothermic
neutralisation
reduction
Fuel cells are used as energy sources in cars. Which row gives a fuel used in a fuel cell and the products formed?
A
B
C
D
Two elements, X and Y, react together to form a covalent molecule as shown. The reaction is exothermic. X2(g) + Y2(g) → 2XY(g) The bond energies are shown in the table.
What is the energy change for the reaction?
+184 kJ / mol
–184 kJ /mol
+247 kJ / mol
–247 kJ /mol
