Question 1

Which of the following is FALSE about the energy diagram shown?

Accepted Answer

A

Question 2

Which of the following statements concerning the reaction below is FALSE? 2HgO(s)→ 2Hg(l)+ O₂(g)∆H = 182 kJ

Accepted Answer

The reaction is endothermic, meaning it absorbs energy (182 kJ) from the surroundings, indicating that the energy of the products is greater than the energy of the reactants, not the other way around. This is because energy is absorbed to break the bonds in HgO, resulting in a net gain of energy in the system.

Question 3

A carbohydrate sample weighing 0.235 g was found to have a fuel value of 3.84 kJ.What is the fuel value of one gram of this carbohydrate,in nutritional Calories? [1 cal = 4.18 J]

Accepted Answer

The fuel value per gram of the carbohydrate can be calculated by dividing the total energy by the mass of the sample: $3.84 \, \text{kJ} / 0.235 \, \text{g} = 16.34 \, \text{kJ/g}$. To convert this to nutritional Calories (where 1 Cal = 1 kcal = 1000 cal), first convert kJ to cal: $16.34 \, \text{kJ/g} \times (1000 \, \text{J/kJ}) / (4.18 \, \text{J/cal}) = 3906.22 \, \text{cal/g}$. Then, convert cal to Cal: $3906.22 \, \text{cal/g} / 1000 = 3.91 \, \text{Cal/g}$.

Question 4

Which statement concerning energy changes in chemical reactions is FALSE?

Accepted Answer

In an exothermic reaction, the products have a lower energy than the reactants, not higher. This is because energy is released to the surroundings, indicating that the reactants had more stored energy that was then released during the reaction.

Question 5

The rate of a chemical reaction increases with an increase in concentration of one or more of the reactants.This is best explained by which of the following statements?

Accepted Answer

The increased concentration of reactants leads to more frequent collisions between reactant molecules, which increases the likelihood of effective collisions that can lead to the formation of products, thus increasing the rate of the reaction.

Question 6

The amount of heat necessary to raise 1 gram of a substance by 1 degree Celsius is known as which of the following?

Accepted Answer

Specific heat is the amount of heat per unit mass required to raise the temperature by one degree Celsius.

Question 7

Which of the following is always necessary for a chemical reaction to occur between two reactants,A and B?

Accepted Answer

For a chemical reaction to occur, reactants A and B must collide with sufficient energy and the correct orientation to break existing bonds and form new ones. This is a fundamental principle of the collision theory in chemistry.

Question 8

What instrument is used for measuring the heat energy absorbed or released in a chemical reaction?

Accepted Answer

A calorimeter is specifically designed to measure the heat energy absorbed or released during a chemical or physical process.

Question 9

For the reaction shown below,Keq=2×10¹¹.Which of the following statements concerning this system at equilibrium is true? 2CO(g)+ O₂(g)⇌ 2CO₂(g)

Accepted Answer

The equilibrium constant (Keq) value of $2 \times 10^{11}$ indicates that the equilibrium lies significantly towards the products, meaning the equilibrium solution contains predominantly $CO_2$.

Question 10

The rate of a chemical reaction increases with an increase in temperature.Which of the following correctly explains why?

Accepted Answer

At higher temperatures, reactant molecules have more kinetic energy, which makes them move faster. This increased movement leads to more frequent collisions and a higher probability of these collisions overcoming the activation energy barrier, thus leading to more effective collisions and an increased rate of reaction.

Question 11

What thermodynamic quantity is the ultimate predictor of reaction spontaneity?

Accepted Answer

The ultimate predictor of reaction spontaneity is the Free Energy Change, ∆G. A negative ∆G indicates a spontaneous process, while a positive ∆G indicates a non-spontaneous process.

Question 12

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)

Accepted Answer

The reaction is endothermic, as indicated by the absorption of 42.5 kcal, so the test tube would feel cold as it absorbs heat from the surroundings.

Question 13

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)]

Accepted Answer

The heat absorbed by the water is calculated as: q = mass × specific heat × temperature change = 982 g × 1.00 cal/(g°C) × 2.62°C = 2572.84 cal. To convert to nutritional Calories (1 Cal = 1000 cal), divide by 1000: 2572.84 cal / 1000 = 2.57284 Cal, which rounds to 2.57 Cal.

Question 14

Which statement concerning a reversible reaction at equilibrium is FALSE?

Accepted Answer

At equilibrium, the rates of the forward and reverse reactions are equal, not necessarily the concentrations of products and reactants.

Question 15

What is the term used to describe the energy barrier the reactants must overcome in order to form products in a chemical reaction?

Accepted Answer

Activation energy is the term used to describe the minimum amount of energy that reactants must possess in order to undergo a specific chemical reaction and form products.

Question 16

The formation of rust (Fe₂O₃)on an exposed piece of metal typically takes several months.Which of the following statements is NOT a reasonable assumption about this chemical reaction? 4Fe(s)+ 3O₂(g)→ 2Fe₂O₃(s)

Accepted Answer

The formation of rust is a slow process, indicating that the reaction has a high activation energy, not a low one. This is why option B is not a reasonable assumption. The other options (A, C, D, E) are reasonable assumptions based on what is known about chemical reactions and their dependence on temperature, concentration of reactants, and the presence of catalysts.

Question 17

What is the equilibrium constant expression for the reaction shown below?

Accepted Answer

The answer of What is the equilibrium constant expression for...

Question 18

Which statement concerning energy changes in chemical reactions is FALSE?

Accepted Answer

The overall change in enthalpy (∆H) for a reaction is determined by the difference in energy between the reactants and the products, not between the products and the activated complex.

Question 19

How many small calories are equivalent to one nutritional Calorie?

Accepted Answer

One nutritional Calorie (with a capital "C"), also known as a kilocalorie, is equivalent to 1,000 small calories (with a lowercase "c").

Question 20

What is the name and symbol of the thermodynamic quantity that represents the heat absorbed or liberated in a chemical reaction at constant pressure?

Accepted Answer

Enthalpy Change, denoted as ∆H, is the thermodynamic quantity that represents the heat absorbed or liberated in a chemical reaction at constant pressure.

Quiz 7: Energy,rate and Equilibrium

Which of the following is FALSE about the energy diagram shown?

Which of the following statements concerning the reaction below is FALSE? 2HgO(s) → 2Hg(l) + O₂(g) ∆H = 182 kJ

A carbohydrate sample weighing 0.235 g was found to have a fuel value of 3.84 kJ.What is the fuel value of one gram of this carbohydrate,in nutritional Calories? [1 cal = 4.18 J]

Which statement concerning energy changes in chemical reactions is FALSE?

The rate of a chemical reaction increases with an increase in concentration of one or more of the reactants.This is best explained by which of the following statements?

The amount of heat necessary to raise 1 gram of a substance by 1 degree Celsius is known as which of the following?

Which of the following is always necessary for a chemical reaction to occur between two reactants,A and B?

What instrument is used for measuring the heat energy absorbed or released in a chemical reaction?

For the reaction shown below,Keq=2×10¹¹.Which of the following statements concerning this system at equilibrium is true? 2CO(g) + O₂(g) ⇌ 2CO₂(g)

The rate of a chemical reaction increases with an increase in temperature.Which of the following correctly explains why?

What thermodynamic quantity is the ultimate predictor of reaction spontaneity?

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 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) ]

Which statement concerning a reversible reaction at equilibrium is FALSE?

What is the term used to describe the energy barrier the reactants must overcome in order to form products in a chemical reaction?

The formation of rust (Fe₂O₃) on an exposed piece of metal typically takes several months.Which of the following statements is NOT a reasonable assumption about this chemical reaction? 4Fe(s) + 3O₂(g) → 2Fe₂O₃(s)

What is the equilibrium constant expression for the reaction shown below?

Which statement concerning energy changes in chemical reactions is FALSE?

How many small calories are equivalent to one nutritional Calorie?

What is the name and symbol of the thermodynamic quantity that represents the heat absorbed or liberated in a chemical reaction at constant pressure?

Quiz 7: Energy,rate and Equilibrium

Which of the following is FALSE about the energy diagram shown?

Which of the following statements concerning the reaction below is FALSE? 2HgO(s) → 2Hg(l) + O2(g) ∆H = 182 kJ

A carbohydrate sample weighing 0.235 g was found to have a fuel value of 3.84 kJ.What is the fuel value of one gram of this carbohydrate,in nutritional Calories? [1 cal = 4.18 J]

Which statement concerning energy changes in chemical reactions is FALSE?

The rate of a chemical reaction increases with an increase in concentration of one or more of the reactants.This is best explained by which of the following statements?

The amount of heat necessary to raise 1 gram of a substance by 1 degree Celsius is known as which of the following?

Which of the following is always necessary for a chemical reaction to occur between two reactants,A and B?

What instrument is used for measuring the heat energy absorbed or released in a chemical reaction?

For the reaction shown below,Keq=2×1011.Which of the following statements concerning this system at equilibrium is true? 2CO(g) + O2(g) ⇌ 2CO2(g)

The rate of a chemical reaction increases with an increase in temperature.Which of the following correctly explains why?

What thermodynamic quantity is the ultimate predictor of reaction spontaneity?

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 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) ]

Which statement concerning a reversible reaction at equilibrium is FALSE?

What is the term used to describe the energy barrier the reactants must overcome in order to form products in a chemical reaction?

The formation of rust (Fe2O3) on an exposed piece of metal typically takes several months.Which of the following statements is NOT a reasonable assumption about this chemical reaction? 4Fe(s) + 3O2(g) → 2Fe2O3(s)

What is the equilibrium constant expression for the reaction shown below?

Which statement concerning energy changes in chemical reactions is FALSE?

How many small calories are equivalent to one nutritional Calorie?

What is the name and symbol of the thermodynamic quantity that represents the heat absorbed or liberated in a chemical reaction at constant pressure?

Which of the following statements concerning the reaction below is FALSE? 2HgO(s) → 2Hg(l) + O₂(g) ∆H = 182 kJ

For the reaction shown below,Keq=2×10¹¹.Which of the following statements concerning this system at equilibrium is true? 2CO(g) + O₂(g) ⇌ 2CO₂(g)

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)

The formation of rust (Fe₂O₃) on an exposed piece of metal typically takes several months.Which of the following statements is NOT a reasonable assumption about this chemical reaction? 4Fe(s) + 3O₂(g) → 2Fe₂O₃(s)