Question :
1.Which of the following always necessary for a chemical reaction : 1318408
1.Which of the following is always necessary for a chemical reaction to occur between two reactants, A and B?
A) A and B must be present in the same physical state.
B) There must be equal amounts of A and B present.
C) A and B must collide with sufficient energy and the proper orientation.
D) The reaction must be carried out at room temperature.
E) The reaction must be carried out at a temperature higher than room temperature.
2.Which statement concerning energy changes in chemical reactions is FALSE?
A) The breaking of bonds requires energy, and the formation of bonds releases energy. B) Activation energy is the minimum amount of energy required to initiate a chemical reaction.
C) A reaction is exothermic if the products have a lower energy than the reactants.
D) A reaction is endothermic if the reactants have a lower energy than the products.
E) The overall energy change in a reaction is determined by the difference in energy between the products and the activated complex.
3.Which of the following is FALSE about the energy diagram shown?
A) The activation energy is 100 kJ.
B) Point 2 on the diagram represents the activated complex.
C) This reaction is exothermic.
D) The energy of the products is lower than the energy of the reactants.
E) ?H = −50 kJ
4.Which statement concerning energy changes in chemical reactions is FALSE?
A) In an exothermic reaction, the system loses heat to the surroundings.
B) In an endothermic reaction, the system absorbs heat from the surroundings.
C) In an endothermic reaction, the reactants have a lower energy than the products.
D) In an exothermic reaction, the products have a higher energy than the reactants.
E) Exothermic reactions are characterized by a negative ?H.
5.Which of the following statements concerning the reaction below is FALSE?
2HgO(s) ? 2Hg(l) + O2(g) ?H = 182 kJ
A) There is an increase in entropy in this reaction.
B) This reaction is endothermic.
C) 182 kJ of energy are required for every two moles of HgO that react.
D) The energy of the reactants is greater than the energy of the products.
E) The system absorbs energy from the surroundings in this reaction.
6.The amount of heat necessary to raise 1 gram of a substance by 1 degree Celsius is known as which of the following?
A) enthalpy
B) activation energy
C) specific heat
D) heat of vaporization
E) free energy
7.Consider the decomposition of calcium carbonate shown below. Which of the following statements correctly describes this reaction as it occurs in a test tube?
CaCO3(s) + 42.5 kcal ? CaO(s) + CO2(g)
A) The test tube would feel warm, since the reaction would absorb heat from the surroundings.
B) The test tube would feel cold, since the reaction would absorb heat from the surroundings.
C) The test tube would feel cold, since the reaction would release heat to the surroundings.
D) The test tube would feel warm, since the reaction would release heat to the surroundings.
E) It is impossible to predict without actually performing the experiment.
8.A candy sample is completely combusted in a bomb calorimeter. The calorimeter contains 982 g of water, and the measured temperature increase is 2.62°C. What is the fuel value of the candy sample in nutritional Calories? [SHw = 1.00 cal/g?°C]
A) 2573 Cal
B) 2570 Cal
C) 2.57 Cal
D) 0.00267 Cal
E) 2.67 × 10−6 Cal
9.Which statement concerning a reversible reaction at equilibrium is FALSE?
A) The concentration of the products is equal to the concentration of the reactants.
B) The forward and reverse reaction rates are equal.
C) There is no further change in the amount of reactants and products.
D) A stress to the system would cause the system to shift in the direction that best relieves the stress.
E) All of the above statements are true for a reversible reaction at equilibrium.
10.What is the term used to describe the energy barrier the reactants must overcome in order to form products in a chemical reaction?
A) energy of inception
B) activation energy
C) enthalpy
D) free energy
E) energy of formation
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john michaelll
