Unit 12

What is the ΔH for the dissociation of 3.500 moles of KNO3(s)?

+122.1kJ KNO3

What is the heat of reaction for the formation of 6.80 moles of Al2O3(s)?

-11393.4kJ Al2O3

What is the change in enthalpy when 84.45 grams of methane (CH4) gas combusts?

-4685kJ CH4

In a chemical reaction, the energy of the reactants is 850 Kj. The energy of the products is 250 Kj. The heat of reaction for this forward reaction is 1. -600 Kj and the reaction is exothermic 2. -600 Kj an the reaction is endothermic 3. +600 Kj and the reaction is exothermic 4. +600 Kj and the reaction is endothermic

1. -600 Kj and the reaction is exothermic

Given the reaction equilibrium: N2 + 3H2 <-> 2NH3 If the pressure is increased at a constant temperature, there will be an increase in the number of moles of 1. NH3, only 2. N2, only 3. H2, only 4. both N2 and H2

1. NH3, only

In a chemical reaction, the use of a catalyst usally results in a decrease in the: 1. activation energy 2. potential energy of the reactant 3. heat reaction 4. amount of products

1. activation energy

The effect of a catalyst on a chemical reaction is to change the: 1. activation energy 2. heat reaction 3. poteintial energy of the product 4. pnteintal energy of the reaction

1. activation energy

Which change may occur when a cyalyst is added to a reactation system? 1. activation energy for reactation decreases 2. the potential energy of the reactants increaases 3. the potential energy of the product decreases 4. the heat of the reaction decreases

1. activation energy for reactation decreases

A(g) + 2B(g) + heat <--> AB2(g) In the equilibrium system the rate of the forward reaction will increase if these is 1. an increase in pressure 2. an increase in the volume if the reaction vessel 3. a decrease in pressure 4. a decrease in the concentration of A(g)

1. an increase in pressure

For any chemical reaction, the heat of reaction is equal to the. 1. heat consent of products minus the heat consent of reactants 2. heat consent of reactants minus the heat consent of products 3. entropy of products minus entropy of reactants 4. entropy of reactants minus entropy of products

1. heat consent of products minus the heat consent of reactants

When a catayst lowers the activation energy of a reaction, the rate of both the forwatd and reverse reacations 1. increase 2. decrease 3. remains the same

1. increase

Given the balanced equation representing a reaction at 101.3 kPa and 298 K. N2 + 3H2 --> 2NH3 + 91.8kJ Which statement is true about this reaction 1. it is exothermic and H equals -91.8kJ 2. It is exothermic and H equals +91.8kJ 3. It is endothermic and H equals -91.8kJ 4. It is endothermic and H equals +91.8kJ

1. it is exothermic and H equals -91.8kJ

Adding a catylst to a chemical reaction will 1. lower the activiation energy needed 2. lower the Pe of the reactants 3. increase the activation energy needed 4. increases the Pe of the reaction

1. lower the activiation energy needed

When of the following does not affect reaction rate? 1. nature of products 2. temperature 3, catylsts 4. concentration of reactants

1. nature of products

Given the equilibrium reaction constant pressure 2HBr + 17.4 kcal <-> H2 + Br When the temperature is increased, the eqilbrium will shift to the 1. right, and the concentration of HBr will decrease 2. right, and the concentration of HBr will increase 3. left , and the concentration of HBr will decrease 4. left, and the concentration of HBr will increase

1. right, and the concentration of HBr will decrease

Which will occur if a catalyst is added to a reaction mixture? 1. the activation energy will be changed 2. only the rate of the forward reaction will be increased 3. only the rae of the reverse reaction will be increased 4. te energy charge (H) of the reaction will be decreased

1. the activation energy will be changed

A student adds two 50.0 mg peices of solid Ca to water. Which change could the student have made that would Most likely increase the rate of reaction? 1. used ten 10.0 mg peice of solid Ca instead 2. used on 100. mg peice pf solid Ca 3. decreased the amout of water presented 4. decreased the temperature of the water

1. used ten 10.0 mg peice of solid Ca instead

According to Table I, which salt releases energy as it dissolves 1. KNO3 2. LiBr 3. NH4NO3 4. NaCl

2. LiBr

Given the reaction at equilibrium: 2SO2 + O2 --> 2SO3 + heat Which change will shift the equilibrium to the right? 1. adding a catalyst 2. adding more O2 3. dereasing he pressure 4. increasing the temperature

2. adding more O2

Given the reaction at equilbrium: N2 + 3H2 <--> 2NH3 1. a decrease in the number of effective collisions 2. an increase in the number of effective collisions 3. a decrease in the activaion energy 4. an incease in the activation energy

2. an increase in the number of effective collisions

Increasing the concentration of reactants or increasing the Kelvin temperature would both 1. cause the heat of reaction to increase 2. cause the number of products to be produced faster 3. decrease the number of "effective" collision 4. increase the time needed to complete the reaction

2. cause the number of products to be produced faster

As the average kinetic energy on a reacion system decreases, the rate of reaction 1. increase 2. decteases 3. remains the same

2. decteases

The combustion of propane is best described as an 1. ecndothermic chemical change 2. endithermic physical change 2. exothermic chemical change 4. exothermic physical change

2. exothermic chemical change

In a reversible reaction, the difference between the activation energy of the foward reaction and the activation energy of the revsrse reaction is equal to the 1. activation complex 2. heat of reactant 3. potential energy of reactants 4. potential energy of products

2. heat of reactant

The difference between the activiation energy of the forward reaction and that of the reverse reaction is really the 1. energy of the reactants 2. heat of reaction 3. energy of the activated complex 4. products final energy

2. heat of reaction

As the temperature of a chemical reaction increases, the rate of reaction: 1. decrease 2. increase 3. remains the same

2. increase

Given the reaction at equilibrium: X2 + 2Y2 <-> 2XY2 + 80kcal The equilibrium point will shift to the right if the pressure is 1. increased and the temperature is increased 2. increased and the temperature is decreased 3. decreased and the temperature is increased 4. decreased and the temperature is decreased

2. increased and the temperature is decreased

If the concentration of one of the reactants In a chemical reaction is increased, the rate if the reaction usally: 1. decreases 2. increases 3. remains same

2. increases

Based on Reference Table I, which of the following reactants relasese the greatest amount of energy? 1. CH4(g) + 2O2(g) --> CO2(g) + 2H2O(l) 2. CO(g) + O2(g) --> CO2(g) 3. C8H18(l) + O2(g) --> 8CO2(g) + 9H2O(l) 4. C6H12O6(s) _ 6O2(g) --> 6CO2(g) + 6H2O(l)

3. C8H18(l) + O2(g) --> 8CO2(g) + 9H2O(l)

Which change of phases is endothermic? 1.CO2(g) --> CO2(s) 2. H2)(l) --> I2(s) 3. I2(s) --> I2(g) 4. H2O(g) --> H2O(l)

3. I2(s) --> I2(g)

Based on Reference Table I reaction has a positive heat of reaction? 1. CH4(g) + 2O2(g) --> CO2(g) + 2H2O(l) 2. CO(g) + O2(g) --> CO2(g) 3. NH4Cl(s) -H2O-> NH4+(aq) + Cl-(aq) 4. H+(aq) + OH-(aq) --> H2O(l)

3. NH4Cl(s) -H2O-> NH4+(aq) + Cl-(aq)

Based on Reference Table I, which of the following reactions relases the greatest amount of energy? 1. CH4(g) + 2O2(g) --> CO2(g) + 2H2O(l) 2. CO(g) + O2(g) --> CO2(g) 3. NH4Cl(s) -H2O-> NH4+(aq) + Cl-(aq) 4. H+(aq) + OH-(aq) --> H2O(l)

3. NH4Cl(s) -H2O-> NH4+(aq) + Cl-(aq)

Concerning potential energy diagrams, which of the following will be the largest in magnitude? 1. forward activiation energy 2. enthalpy 3. energy of activated complex 4. energy of the products

3. energy of activated complex

In a gas phase system at constant temperature, an increase in pressure will 1. increase the activation energy 2. decrease the activation energy 3. increase the reaction rate 4. decrease the reaction rate

3. increase the reaction rate

In a gaseous system, temperature remaining contant, an increae in pressure will: 1. increase the activation energy 2. decrease the activation energy 3. increase the reaction rate 4. decrease the reaction rate

3. increase the reaction rate

Zn + 2 HCl --> ZnCl2 + H2 The rate of this reaction can be increased by using 5.0 grams of powder zinc instead of a 5.0- gram strip of zinc because the powdered zinc has 1. lower kinetic energy 2. lower concentration 3. more surface area 4. more zinc atoms

3. more surface area

As increase in temperature increases the rate of a chemical reaction because the 1. activation energy increases 2. activation energy decreases 3. number of molecular collisions increases 4. number of molecular collisions decreases

3. number of molecular collisions increases

Which statment about a system at equilibrium is true? 1. the forward reaction rate is less than the reverse reaction rate. 2. the forward reaction rate is greater than the reverse reaction rate. 3. the forward reaction rate is equal than the reverse reaction rate. 4. the forward reaction rate stops and the the reverse reaction rate contiues..

3. the forward reaction rate is equal than the reverse reaction rate.

In a chemical reaction, the difference in potential energy between the products and the reactants is equal to 1. ΔS 2. ΔG 3. ΔH 4. ΔT

3. ΔH

Given the reaction at equilibroim: 2H3 + O2 <-> 2H2O + heat Which concentration changes occur when the temperature of the system is increased? 1. The H2 decreases and the O2 decreases 2. The H2 decreases and the O2 increase 3. The H2 increase and the O2 decreases 4. The H2 increase and the O2 increase

4. The H2 increase and the O2 increase

2POCl3 + energy <-> 2PCl3 + O2 Which changes occur when O2 is added to this system? 1. The equilibrium shifts to the right and the concentration of PCl3 increases 2. The equilibrium shifts to the right and the concentration of PCl decreases 3. The equilibrium shifts to the left and the concentration of PCl3 increases 4. The equilibrium shifts to the left and the concentration of PCl3 decrease

4. The equilibrium shifts to the left and the concentration of PCl3 decrease

The addition of a catalys to a reaction changes the potential energy of the 1. products 2. rectants 3. catalyst 4. activated complexes

4. activated complexes

A (s) + B (aq) --> C (aq) + D (s) Whoch change most likly increase the rate of the formation of products? 1. a decrease in pressure 2. an increase in pressure 3. a decrease in the Kenetic Energy 4. an increase in the Kinetic Energy

4. an increase in the Kinetic Energy

"Lowering the activation energy to increase the rate of the reaction" is really the denfinition of a (an) 1. reactant 2. enthalpy 3. concentration 4. catalyst

4. catalyst

Consider the reaction: H2O(l) + energy --> H2(g) + 1/2 O2(g) Which phases best describes this reaction? 1. exothermic, relasing energy 2. exothermic, absorbing energy 3. endothermic, release energy 4. endothermic, absorbing energy

4. endothermic, absorbing energy

H2O(l) + energy --> H2(g) + O2(g) Which phrase best describes the following reaction? 1. exothermic, releasing energy 2. exothermic, absorbing energy 3. endothermic, relasing energy 4. endothermic, absorbing energy

4. endothermic, absorbing energy

As the temperature in a reaction system inceases, the number of effective collisions between reactants particles 1. first increase, than decrease 2. decrease, only 3. first decreases, then increase 4. increase, only

4. increase, only

Which conditions will increase the rate of a chemical reaction? 1. decreased temperature and deceased concentration of reactants 2. decreased temperature and increased concentration of reactants 3. increased temperature and deceased concentration of reactants 4. increased temperature and increased concentration of reactants

4. increased temperature and increased concentration of reactants

Based on Referance Tables I how many Kilo Joales of heat are produced when 0.5 mole of C2H6 is formed from its elements?

40kJ

A catalyst can increase the rate of a reaction by A. increasing the activation energy B) decreasing the activation energy C) increasing the portential energy of the products D. decreasing the potential energy of the products

B) decreasing the activation energy

4Fe + 3O2 --> 2Fe2O3 + 1640kJ Which phrase best describes this reaction? A) endothermic with ΔH = +1640kJ B) exothermic with ΔH = -1640kJ C) exothermic with ΔH = +1640kJ D) endothermic with ΔH = -1640kJ

B) exothermic with ΔH = -1640kJ

2H2 + O2 --> 2H2O + 571.6kJ What is the approximate ΔH for the formation of 1 moles of H2O? A) + 284.8kJ B) +571.6kJ C) -285.8kJ D) -571.6kJ

C) -285.8kJ

A 1.0 gram piece of zinc reacts with 5 milliters of HCl(aq). Which of theses conditions of concentration and temperature would produce the greatest rate of reaction? A) 2.0 M HCl(aq) at 20°C B) 1.0 M HCl(aq) at 40°C C) 2.0 M HCl(aq) at 40°C D) 1.0 M HCl(aq) at 20°C

C) 2.0 M HCl(aq) at 40°C

Which statment correctly describes an endothermic chemical reaction? A) The products have higher potential energy than the reactants, and the ΔH is negitive B) The product have lower potential energy than the reactants, and the ΔH is positive C) The products have higher potential energy than the reactants, and the ΔH is positive D) The products have lower potential energy than the reactants, and the ΔH is negitive

C) The products have higher potential energy than the reactants, and the ΔH is positive

In a chemical reaction, the difference between the potential energy of the products and the potential energy of the reactants is defined as the A) heat of vaporization B) ionization energy C) heat of reaction D) activation energy

C) heat of reaction

A(g) + B(g) --> C(g) As the concentration of A(g) increases, the frequency of collisions of A(g) with B(g) A) remains the same B) decreases C) increases

C) increases

A cataylst increases the rate of a chemical reaction by A) lowering the potential energy of the products B) raising the temperature of the reactants C) lowering the activation energy of the reaction D) raising the concentration of the reactants

C) lowering the activation energy of the reaction

A + B --> C + D The reaction will most likely occur at the greatest rate if A and B respresents A) solutions of nonpolar molecular compounds B) ionic compounds in the solid phase C) solutions of ionic compounds D) nonpolar molecular compounds in the solid phase

C. solutions of ionic compounds

According to the Heats of Reaction at 101.3 kPa and 298 K chemistry refence table, which salt releases energy as it dissolves? A) LiBr B) NH4NO3 C) KNO3 D) NaCl

D) NaCl

Based on the nature of the reactants in each of the equations below, which reaction at 25°C will occur at the fastest rate? A) C(s) + O2(g) --> CO2(g) B) CaCO3(s) --> CaO(S) + CO2(g) C) CH3OH(l) + CH3COOH(l) --> CH3OOCH3(aq) + H2O(l) D) NaOH(aq) + HCl(aq) --> NaCl(aq) + H2O(l)

D) NaOH(aq) + HCl(aq) --> NaCl(aq) + H2O(l)

Which of the following statments explains why the speed of some chemical reactions is increased when the surface area of the reactant is increased? A) This change alters the electrical conductivity of the reactant particles. B) This change increases the concentration of the reactant C) This change increases the density of the reactant particles D) This change exposes more reactant particles to possible collision

D) This change exposes more reactant particles to possible collision

In order for a chemical reaction to occur, there must always be A) reacting particles with a high kinetic energy B) a bond that breaks in a reactant particle C) reacting particles with a high charge D) an effective collision between reacting particles

D) an effective collision between reacting particles

Raising the temperature speeds up the rate of a chemical reaction by increaseing A) the effectiveness of the collisions, only B) neither the effectiveness nor the frequency of the collisions C) the frequency of the collisions, only D) both the effectiveness and the frequency of the collisions

D) both the effectiveness and the frequency of the collisions

Which condition will increase the rate of a chemical reaction? A) decreased temperature and decreased concentration of reactants B) increased temperature and decreased concentration of reactants C) decreased temperature and increased concentration of reactants D) increased temperature and increased concentration of reactants

D) increased temperature and increased concentration of reactants

Increasing the temperature increases the rate of a reaction by A) lowering the activation energy B) lowering the frequency of effective colloisons between molecules C) increasing the activated energy D) increasing the frequency of effective collisions between reacting molecules

D) increasing the frequency of effective collisions between reacting molecules

Use the information in the table I of your chemistry refence tables to write the correct thermochemical equation for the dissociation of NH4Cl(s).

H2O +14.78kJ + NH4Cl(s) --> NH4+(aq) + Cl-(aq)

Use the information in the table I of your chemistry refence tables to write the correct thermochemical equation for the synthesis of NH3(g).

N29g) + 3H2(g) --> 2NH3(g) + -91.8kJ

What is true about the quanity of reactants and products when a system is at equilibrium?

Qualities are constant when at equlibrium

CH4(g) + 2O2(g) <--> CO2(g) + 2H2O(I) If more H2O(l) is added to the reaction vessel, what will occur? The concentration of H2O(l) will (increase/decrease)

decrease

CH4(g) + 2O2(g) <--> CO2(g) + 2H2O(I) If more O2(g) is added to the reaction vessel, what will occur? The concentration of CH4(g) will (increase/decrease)

decrease

CH4(g) + 2O2(g) <--> CO2(g) + 2H2O(I) If the some CH4(g) is removed from the reaction vessel, what will occur? The concentration of H2O(l) and CO2(g) will (increase/decrease)

decrease

CH4(g) + 2O2(g) <--> CO2(g) + 2H2O(I) If the some CO2(g) is removed from the reaction vessel, what will occur? The concentration of O2(g) and CH4(g) will (increase/decrease)

decrease

CH4(g) + 2O2(g) <--> CO2(g) + 2H2O(I) If more O2(g) is added to the reaction vessel, what will occur? The (forward/reverse) reaction rate will increase

forward

CH4(g) + 2O2(g) <--> CO2(g) + 2H2O(I) If more O2(g) is added to the reaction vessel, what will occur? The (forward/reverse) reaction will be favored.

forward

CH4(g) + 2O2(g) <--> CO2(g) + 2H2O(I) If the some CO2(g) is removed from the reaction vessel, what will occur? The (forward/reverse) reaction rate will increase

forward

CH4(g) + 2O2(g) <--> CO2(g) + 2H2O(I) If the some CO2(g) is removed from the reaction vessel, what will occur? The forward/revese) reaction will be fovored

forward

CH4(g) + 2O2(g) <--> CO2(g) + 2H2O(I) If more H2O(l) is added to the reaction vessel, what will occur? The concentration of CH4(g) and O2(g) will (increase/decrease)

increase

CH4(g) + 2O2(g) <--> CO2(g) + 2H2O(I) If more O2(g) is added to the reaction vessel, what will occur? The concentration of CO2(g) and H2O(l) will (increase/decrease)

increase

CH4(g) + 2O2(g) <--> CO2(g) + 2H2O(I) If the some CH4(g) is removed from the reaction vessel, what will occur? The concentration of O2(g) will (increase/decrease)

increase

CH4(g) + 2O2(g) <--> CO2(g) + 2H2O(I) If the some CO2(g) is removed from the reaction vessel, what will occur? The concentation of H2O(l) will (increse/decrease)

increse

CH4(g) + 2O2(g) <--> CO2(g) + 2H2O(I) If more H2O(l) is added to the reaction vessel, what will occur? The equilbrium will shift (right/left/no shift)

left

CH4(g) + 2O2(g) <--> CO2(g) + 2H2O(I) If the some CH4(g) is removed from the reaction vessel, what will occur? The equilibrium will shift (right/left/no shift)

left

A system is at equilibrium when...

rates of the foward reaction and reverse reaction are equal

according to le chateliers principle, why does a reactionś equilibrium shift when a stress is applied to it?

releve stress

CH4(g) + 2O2(g) <--> CO2(g) + 2H2O(I) If more H2O(l) is added to the reaction vessel, what will occur? The (forward/reverse) reaction rate will increase

reverse

CH4(g) + 2O2(g) <--> CO2(g) + 2H2O(I) If more H2O(l) is added to the reaction vessel, what will occur? The (forward/reverse) reaction will be favored

reverse

CH4(g) + 2O2(g) <--> CO2(g) + 2H2O(I) If the some CH4(g) is removed from the reaction vessel, what will occur? The (forward/reverse) reaction rate will increase

reverse

CH4(g) + 2O2(g) <--> CO2(g) + 2H2O(I) If the some CH4(g) is removed from the reaction vessel, what will occur? The (forward/reverse) reaction will be favored

reverse

CH4(g) + 2O2(g) <--> CO2(g) + 2H2O(I) If more O2(g) is added to the reaction vessel, what will occur? The equilibrium will shift (right/left/no shift)

right

CH4(g) + 2O2(g) <--> CO2(g) + 2H2O(I) If the some CO2(g) is removed from the reaction vessel, what will occur? The equilibrium will shift (right/left/no shift)

right