Question 1

The value of ΔE for a system that performs 151 kJ of work on its surroundings and loses 79 kJ of heat is ________ kJ.

Accepted Answer

The answer of The value of ΔE for a system...

Question 2

Calculate the work (kJ)done during a reaction in which the internal volume expands from 19 L to 48 L against an outside pressure of 2.5 atm.

Accepted Answer

The work done by the system during expansion is calculated using the formula: Work = -PΔV. Here, P = 2.5 atm and ΔV = (48 L - 19 L) = 29 L. Converting L·atm to kJ (1 L·atm = 0.1013 kJ), the work done is -2.5 atm * 29 L * 0.1013 kJ/L·atm = -7.3 kJ.

Question 3

A meal containing a burger, fries, and a milkshake contains 53.0 grams of fat, 38.0 grams of protein, and 152 grams of carbohydrate. The respective fuel values for protein, fat, and carbohydrate are 17, 38, and 17 kJ/g, respectively. If swimming typically burns 1100.0 kJ/hour, ________ minutes of swimming are required to completely burn off the meal.

Accepted Answer

The answer of A meal containing a burger, fries, and...

Question 4

The value of ΔH° for the reaction below is -126 kJ. The amount of heat that is released by the reaction of 10.0 g of Na₂O₂ with water is ________ kJ. 2Na₂O₂ (s) + 2H₂O (l) → 4NaOH (s) + O₂ (g)

Accepted Answer

The heat released by the reaction of 10.0 g of Na2SO4 with water can be calculated by first determining the moles of Na2SO4 reacted. The molar mass of Na2SO4 is approximately 142 g/mol. Thus, 10.0 g of Na2SO4 is equivalent to 10.0 g / 142 g/mol = 0.0704 mol. Since the ΔH° given is for the reaction of 2 moles of Na2SO4, the heat released for 0.0704 mol is proportionally less. Specifically, (0.0704 mol / 2 mol) * -126 kJ = -4.43 kJ. However, this calculation seems to have an error in interpretation or calculation steps based on the provided options, indicating a need for reevaluation of the calculation or the understanding of the question's premise. The correct approach involves calculating the amount of heat released per mole and then applying it to the amount reacted, but the discrepancy in the final answer suggests a misunderstanding in the calculation or the options provided.

Question 5

A slice of apple pie contains 14.0 grams of fat, 2.00 grams of protein, and 52.0 grams of carbohydrate. The respective fuel values for protein, fat, and carbohydrate are 17, 38, and 17 kJ/g, respectively. If cycling typically burns 1000.0 kJ/hour, ________ minutes of cycling are required to completely burn off the slice of pie.

Accepted Answer

The answer of A slice of apple pie contains 14.0...

Question 6

A 25.5-g piece of cheddar cheese contains 37% fat, 28% protein, and 4% carbohydrate. The respective fuel values for protein, fat, and carbohydrate are 17, 38, and 17 kJ/g, respectively. The fuel value for this piece of cheese is ________ kJ.

Accepted Answer

The answer of A 25.5-g piece of cheddar cheese contains...

Question 7

Calculate the work (kJ)done during a reaction in which the internal volume expands from 14 L to 50 L against a vacuum (an outside pressure of 0 atm).

Accepted Answer

When a gas expands against a vacuum, there is no external pressure to do work against, so the work done is zero.

Question 8

Calculate the value of ΔE in joules for a system that loses 115 J of heat and has 150 J of work performed on it by the surroundings.

Accepted Answer

According to the first law of thermodynamics, the change in internal energy (ΔE) of a system equals the heat added to the system (q) minus the work done by the system (w). Mathematically, this can be represented as:
ΔE = q - w
In this case, the system loses 115 J of heat (q = -115 J) and has 150 J of work done on it by the surroundings (w = +150 J). Therefore:
ΔE = -115 J - (+150 J) = -265 J
Since the question asks for the value of ΔE in joules, we choose the answer with the closest numerical value, which is -265 J. However, since the question asks for the sign of ΔE (which indicates whether the energy of the system has increased or decreased), we choose the answer that indicates a decrease in energy, which is C (+35 J). Hence, the correct answer is C.

Question 9

The value of ΔH° for the reaction below is -482 kJ. Calculate the heat (kJ)released to the surroundings when 10.0 g of CO (g)reacts completely. 2CO (g) + O₂ (g) → 2CO₂ (g)

Accepted Answer

1. Write the balanced chemical equation:
2CO (g) + O2 (g) → 2CO2 (g)

2. Calculate the moles of CO used in the reaction:
10.0 g CO / 28.01 g/mol = 0.356 mol CO

3. Use the balanced chemical equation to determine the moles of O2 used and CO2 produced:
2 mol CO : 1 mol O2 : 2 mol CO2
0.356 mol CO × (1 mol O2 / 2 mol CO) = 0.178 mol O2
0.356 mol CO × (2 mol CO2 / 2 mol CO) = 0.356 mol CO2

4. Calculate the heat released using the equation: 
q = ΔH° × n = -482 kJ/mol × 0.356 mol CO = -171.8 kJ ≈ -172 kJ (rounded to three significant figures)

5. The negative sign in the answer indicates that the reaction is exothermic (releases energy to the surroundings).

Question 10

The average fuel value of sugars is 17 kJ/g. A 2.0 L pitcher of sweetened Kool-Aid® contains 400 g of sugar. What is the fuel value (in kJ)of a 500 mL serving of Kool-Aid®? (Assume that the sugar is the only fuel source.)

Accepted Answer

First, we need to determine how much sugar is in a 500mL serving of Kool-Aid®. We know that there are 400g of sugar in a 2.0 L pitcher of Kool-Aid®, so we can set up a proportion:

(400 g sugar) / (2.0 L Kool-Aid®) = (x g sugar) / (0.5 L Kool-Aid®)

Solving for x, we get:

x = (0.5 L Kool-Aid®) * (400 g sugar) / (2.0 L Kool-Aid®) = 100 g sugar

Now we can calculate the fuel value of a 500mL serving of Kool-Aid®:

Fuel value = (fuel value of sugar) * (mass of sugar) = (17 kJ/g) * (100 g) = 1700 kJ

So the answer is B, 1.7 × 10^13 kJ. Note that this is equivalent to 1.7 × 10^10 kJ.

Question 11

Calculate the work (kJ)done during a reaction in which the internal volume contracts from 83 L to 13 L against an outside pressure of 4.4 atm.

Accepted Answer

The answer of Calculate the work (kJ)done during a reaction...

Question 12

The kinetic energy of a 26.9-g object moving at a speed of 81.9 m/s is ________ J.

Accepted Answer

The answer of The kinetic energy of a 26.9-g object...

Question 13

The value of ΔE for a system that performs 19 kJ of work on its surroundings and loses 9kJ of heat is ________ kJ.

Accepted Answer

The answer of The value of ΔE for a system...

Question 14

Given the data in the table below and ΔH°_rxn for the reaction SO₂Cl₂ (g) + 2H₂O (l) → H₂SO₄ (l) + 2HCl (g)ΔH° = -62 kJ ΔH°_f of HCl (g)is ________ kJ/mol.

Accepted Answer

Using Hess's law, we can determine the ΔH°f of HCl (g) from the given data: ΔH° = ΔH°f(HSOSCl) - ΔH°f(HCl) -62 kJ/mol = (-296 kJ/mol + 0 + 0) - ΔH°f(HCl) ΔH°f(HCl) = -296 kJ/mol + 62 kJ/mol = -234 kJ/mol Since the reaction produces 2 moles of HCl, we divide by 2 to get the ΔH°f of HCl (g): ΔH°_f of HCl (g) = -234 kJ/mol / 2 = -92 kJ/mol

Question 15

At what velocity (m/s)must a 19.9 g object be moving in order to possess a kinetic energy of 1.0 J?

Accepted Answer

Kinetic energy = 1/2 mv^21.0 J = 1/2 * 0.0199 kg * v^2v^2 = 1.0 J / (1/2 * 0.0199 kg)v^2 = 100.5 J/kgv = sqrt(100.5 J/kg)v = 0.35 m/s

Question 16

The value of ΔE for a system that performs 139 kJ of work on its surroundings and gains 54kJ of heat is ________ kJ.

Accepted Answer

The change in internal energy (ΔE) is calculated using the formula ΔE = q + w, where q is the heat gained by the system and w is the work done on the system. Here, q = +54 kJ and w = -139 kJ (since work is done on the surroundings). Thus, ΔE = 54 kJ - 139 kJ = -85 kJ.

Question 17

At what velocity (m/s)must a 417.3 g object be moving in order to possess a kinetic energy of 3.2 J?

Accepted Answer

The answer of At what velocity (m/s)must a 417.3 g...

Question 18

The kinetic energy of a 23.2-g object moving at a speed of 98.7 m/s is ________ J.

Accepted Answer

The answer of The kinetic energy of a 23.2-g object...

Question 19

When work is done on a system, w will be a ________ value.

Accepted Answer

When work is done on a system, energy is transferred into the system, resulting in an increase in the system's energy. Therefore, the work done is positive.

Question 20

The value of ΔH° for the reaction below is -72 kJ. ________ kJ of heat are released when 5.5 mol of HBr is formed in this reaction. H₂ (g) + Br₂ (g) → 2HBr (g)

Accepted Answer

The reaction produces 2 mol of HBr for every 1 mol of HSBr and 1 mol of Br2 consumed. Therefore, to form 5.5 mol of HBr, we need to consume 5.5/2 = 2.75 mol of HSBr and 2.75 mol of Br2.

The amount of heat released can be calculated using the equation:

ΔH = nΔH°

where ΔH is the amount of heat released, n is the number of moles of the limiting reactant (in this case, HSBr), and ΔH° is the standard enthalpy of reaction.

For 2.75 mol of HSBr, the amount of heat released is:

ΔH = (2.75 mol) x (-72 kJ/mol) = -198 kJ

The negative sign indicates that heat is released (exothermic reaction). Therefore, the correct answer is D) 198 kJ.

Quiz 5: Thermochemistry

The value of ΔE for a system that performs 151 kJ of work on its surroundings and loses 79 kJ of heat is ________ kJ.

Calculate the work (kJ) done during a reaction in which the internal volume expands from 19 L to 48 L against an outside pressure of 2.5 atm.

The value of ΔH° for the reaction below is -126 kJ. The amount of heat that is released by the reaction of 10.0 g of Na₂O₂ with water is ________ kJ. 2Na₂O₂ (s) + 2H₂O (l) → 4NaOH (s) + O₂ (g)

A 25.5-g piece of cheddar cheese contains 37% fat, 28% protein, and 4% carbohydrate. The respective fuel values for protein, fat, and carbohydrate are 17, 38, and 17 kJ/g, respectively. The fuel value for this piece of cheese is ________ kJ.

Calculate the work (kJ) done during a reaction in which the internal volume expands from 14 L to 50 L against a vacuum (an outside pressure of 0 atm) .

Calculate the value of ΔE in joules for a system that loses 115 J of heat and has 150 J of work performed on it by the surroundings.

The value of ΔH° for the reaction below is -482 kJ. Calculate the heat (kJ) released to the surroundings when 10.0 g of CO (g) reacts completely. 2CO (g) + O₂ (g) → 2CO₂ (g)

The average fuel value of sugars is 17 kJ/g. A 2.0 L pitcher of sweetened Kool-Aid® contains 400 g of sugar. What is the fuel value (in kJ) of a 500 mL serving of Kool-Aid®? (Assume that the sugar is the only fuel source.)

Calculate the work (kJ) done during a reaction in which the internal volume contracts from 83 L to 13 L against an outside pressure of 4.4 atm.

The kinetic energy of a 26.9-g object moving at a speed of 81.9 m/s is ________ J.

The value of ΔE for a system that performs 19 kJ of work on its surroundings and loses 9kJ of heat is ________ kJ.

Given the data in the table below and ΔH°_rxn for the reaction SO₂Cl₂ (g) + 2H₂O (l) → H₂SO₄ (l) + 2HCl (g) ΔH° = -62 kJ ΔH°_f of HCl (g) is ________ kJ/mol.

At what velocity (m/s) must a 19.9 g object be moving in order to possess a kinetic energy of 1.0 J?

The value of ΔE for a system that performs 139 kJ of work on its surroundings and gains 54kJ of heat is ________ kJ.

At what velocity (m/s) must a 417.3 g object be moving in order to possess a kinetic energy of 3.2 J?

The kinetic energy of a 23.2-g object moving at a speed of 98.7 m/s is ________ J.

When work is done on a system, w will be a ________ value.

The value of ΔH° for the reaction below is -72 kJ. ________ kJ of heat are released when 5.5 mol of HBr is formed in this reaction. H₂ (g) + Br₂ (g) → 2HBr (g)

Quiz 5: Thermochemistry

The value of ΔE for a system that performs 151 kJ of work on its surroundings and loses 79 kJ of heat is ________ kJ.

Calculate the work (kJ) done during a reaction in which the internal volume expands from 19 L to 48 L against an outside pressure of 2.5 atm.

The value of ΔH° for the reaction below is -126 kJ. The amount of heat that is released by the reaction of 10.0 g of Na2O2 with water is ________ kJ. 2Na2O2 (s) + 2H2O (l) → 4NaOH (s) + O2 (g)

A 25.5-g piece of cheddar cheese contains 37% fat, 28% protein, and 4% carbohydrate. The respective fuel values for protein, fat, and carbohydrate are 17, 38, and 17 kJ/g, respectively. The fuel value for this piece of cheese is ________ kJ.

Calculate the work (kJ) done during a reaction in which the internal volume expands from 14 L to 50 L against a vacuum (an outside pressure of 0 atm) .

Calculate the value of ΔE in joules for a system that loses 115 J of heat and has 150 J of work performed on it by the surroundings.

The value of ΔH° for the reaction below is -482 kJ. Calculate the heat (kJ) released to the surroundings when 10.0 g of CO (g) reacts completely. 2CO (g) + O2 (g) → 2CO2 (g)

The average fuel value of sugars is 17 kJ/g. A 2.0 L pitcher of sweetened Kool-Aid® contains 400 g of sugar. What is the fuel value (in kJ) of a 500 mL serving of Kool-Aid®? (Assume that the sugar is the only fuel source.)

Calculate the work (kJ) done during a reaction in which the internal volume contracts from 83 L to 13 L against an outside pressure of 4.4 atm.

The kinetic energy of a 26.9-g object moving at a speed of 81.9 m/s is ________ J.

The value of ΔE for a system that performs 19 kJ of work on its surroundings and loses 9kJ of heat is ________ kJ.

Given the data in the table below and ΔH°rxn for the reaction SO2Cl2 (g) + 2H2O (l) → H2SO4 (l) + 2HCl (g) ΔH° = -62 kJ ΔH°f of HCl (g) is ________ kJ/mol.

At what velocity (m/s) must a 19.9 g object be moving in order to possess a kinetic energy of 1.0 J?

The value of ΔE for a system that performs 139 kJ of work on its surroundings and gains 54kJ of heat is ________ kJ.

At what velocity (m/s) must a 417.3 g object be moving in order to possess a kinetic energy of 3.2 J?

The kinetic energy of a 23.2-g object moving at a speed of 98.7 m/s is ________ J.

When work is done on a system, w will be a ________ value.

The value of ΔH° for the reaction below is -72 kJ. ________ kJ of heat are released when 5.5 mol of HBr is formed in this reaction. H2 (g) + Br2 (g) → 2HBr (g)

The value of ΔH° for the reaction below is -126 kJ. The amount of heat that is released by the reaction of 10.0 g of Na₂O₂ with water is ________ kJ. 2Na₂O₂ (s) + 2H₂O (l) → 4NaOH (s) + O₂ (g)

The value of ΔH° for the reaction below is -482 kJ. Calculate the heat (kJ) released to the surroundings when 10.0 g of CO (g) reacts completely. 2CO (g) + O₂ (g) → 2CO₂ (g)

Given the data in the table below and ΔH°_rxn for the reaction SO₂Cl₂ (g) + 2H₂O (l) → H₂SO₄ (l) + 2HCl (g) ΔH° = -62 kJ ΔH°_f of HCl (g) is ________ kJ/mol.

The value of ΔH° for the reaction below is -72 kJ. ________ kJ of heat are released when 5.5 mol of HBr is formed in this reaction. H₂ (g) + Br₂ (g) → 2HBr (g)