Question 1

When one mole of gaseous hydrogen peroxide,H₂O₂,is made from hydrogen and oxygen gases,the enthalpy change is -136 kJ.Which of the following correctly represents the thermochemical equation? (i)H₂(g)+ O₂(g)$\rightarrow$H₂O₂(g)+ 136 kJ (ii)H₂(g)+ O₂(g)+ 136 kJ $\rightarrow$ H₂O₂(g) (iii)H₂(g)+ O₂(g)$\rightarrow$ H₂O₂(g)?0?H = -136 kJ (iv)H₂(g)+ O₂(g)$\rightarrow$ H₂O₂(g)?0?H = +136 kJ

Accepted Answer

The correct thermochemical equation should have the products and reactants on opposite sides of the reaction arrow and should include the correct enthalpy change. Option i has the correct placement of reactants and products but the enthalpy change is not included in the equation. Option ii has the enthalpy change included but has the products and reactants on the same side of the arrow. Option iii has the correct placement of reactants and products but the enthalpy change is labeled as ?0?H instead of -136 kJ. Option iv has the correct placement of reactants and products and the correct enthalpy change, so the best answer is i and iii.

Question 2

Ammonium sulfate can be made by the reaction H₂SO₄ + 2 NH₃ $\rightarrow$(NH₄)₂SO₄.What quantity of ammonium sulfate will result from the reaction of 5.00 kg of ammonia and 20.0 kg of sulfuric acid?

Accepted Answer

The answer of Ammonium sulfate can be made by the...

Question 3

Formation of two moles of hydrogen chloride gas from the gases hydrogen and chlorine is a reaction for which $\Delta$H is -185 kJ.Which of the following statements is correct?
(i)The reaction is exothermic.
(ii)Enthalpy of the system decreases.
(iii)Heat is a "product".

Accepted Answer

(i) The negative value of the enthalpy change (-185 kJ) indicates that the reaction is exothermic, as energy is released to the surroundings.
(ii) The enthalpy of the system decreases, as indicated by the negative value of the enthalpy change (-185 kJ). 
(iii) Heat is a "product" because it is released to the surroundings during the reaction.

Question 4

How much energy is required to produce 1.00 kg of aluminum by the reaction 2 Al₂O₃(s)+ 3 C(s)+ 1.97 * 10³ kJ $\rightarrow$4 Al(s)+ 3 CO₂(g)?

Accepted Answer

The answer of How much energy is required to produce...

Question 5

$\Delta$H = +572 kJ for the decomposition of water by the reaction 2 H₂O( )$\rightarrow$2 H₂(g)+ O₂(g).How many grams of water can be decomposed by 5.00 *10³ kJ of energy?

Accepted Answer

First, we need to calculate how many moles of energy are needed to decompose water:
572 kJ x (1 mol H2O / 483.6 kJ) = 1 mol H2O
So, 5.00 x 10^10 kJ of energy can decompose:
(5.00 x 10^10 kJ) x (1 mol / 1.204 x 10^-2 mol) x (1/2) x (18.015 g / 1 mol) = 3.15 x 10^5 g = 315 g of water.

Therefore, the answer is B) 315 g.

Question 6

The metabolism of glucose can be represented by the equation C₆H₁₂O₆(s)+ 6 O₂(g)$\rightarrow$6 CO₂(g)+ 6 H₂O(g)$\Delta$H = -2.82 *10³ kJ.How many grams of glucose must be metabolized to produce 282 kJ of energy?

Accepted Answer

The given reaction releases 2820 kJ per mole of glucose. To produce 282 kJ, 1/10th of a mole of glucose is needed. The molar mass of glucose is 180 g/mol, so 1/10th of a mole is 18.0 g.

Question 7

Cu₂HgI₄ is prepared according to the equation 2 CuI + HgI₂ $\rightarrow$Cu₂HgI₄.When 2.00 g of each reactant are used,which one is the limiting reactant?

Accepted Answer

The answer of Cu₂HgI₄ is prepared according to the equation...

Question 8

A typical diet provides about 2000 food Calories per day,or 2000 kilocalories.Calculate the equivalent number of joules.

Accepted Answer

2000 kilocalories is equivalent to 8.4 million joules. When converting between units of energy, it is important to use the correct conversion factor, which is 1 food Calorie = 4184 joules. Therefore, 2000 Calories is equal to 2000 x 4184 = 8,368,000 joules. Rounded to the nearest million, this is 8.4 million joules, which is closest to choice C.

Question 9

A typical candy bar contains 281 food Calories,which is 281 kcal.How many kilojoules are contained in one such candy bar?

Accepted Answer

1 food calorie is equal to 4.184 kilojoules. Therefore, to convert 281 food Calories to kilojoules, we multiply by 4.184:

281 kcal x 4.184 kJ/kcal = 1177.804 kJ

Rounding to two significant figures gives 1.18 x 10^3 kJ, which is answer choice B.

Question 10

When 1.00 g of C₆H₁₂O₆(s)is formed during photosynthesis,15.67 kJ of the sun's energy is converted to chemical energy.What is the thermochemical equation for the photosynthesis of glucose?

Accepted Answer

The answer of When 1.00 g of C₆H₁₂O₆(s)is formed during...

Question 11

If the reaction N₂ + 3 H₂ $\rightarrow$2 NH₃ is carried out using 1.40 g of N₂ and 0.400 g of H₂,what mass of excess reactant will remain?

Accepted Answer

The answer of If the reaction N₂ + 3 H₂...

Question 12

The thermochemical equation describing the heat change in the decomposition of limestone,CaCO₃,is given by CaCO₃(s)+ 176 kJ$\rightarrow$ CaO(s)+ CO₂(g).What is the heat change that accompanies the decomposition of 25.0 g of limestone?

Accepted Answer

The answer of The thermochemical equation describing the heat change...

Question 13

Consider the following thermochemical equation: CaO(s)+ H₂O( )$\rightarrow$ Ca(OH)₂(s)$\Delta$H = -66.5 kJ Which of the following statements is/are correct? (i)The reaction is exothermic (ii)The reaction releases 66.5 kJ per gram of Ca(OH)₂(s)formed (iii)Alternatively,the$\Delta$H term could be added to the product side of the equation

Accepted Answer

The answer of Consider the following thermochemical equation: CaO(s)+ H₂O(...

Question 14

Convert 357 J to kcal.

Accepted Answer

1 calorie = 4.184 joules, so 357 J = 357 / 4.184 = 85.3 calories = 0.0853 kcal.

Question 15

The decomposition of potassium chlorate is written as shown below.What energy change occurs when 12.3 g of KClO₃ decompose? 2 KClO₃(s)+ 89.6 kJ $\rightarrow$ 2 KCl(s)+ 3 O₂(g)

Accepted Answer

The answer of The decomposition of potassium chlorate is written...

Question 16

Aqueous HCl is added to an aqueous solution of NaOH at 25 °C and the result is shown in the figure below.  Which of the following correctly characterizes this reaction?

Accepted Answer

The graph shows a decrease in temperature during the reaction, indicating that energy is being released and the reaction is exothermic.

Question 17

A chemist combines hydrochloric acid with a sodium hydroxide solution,transferring 5.75 kJ of heat.Express this in calories.

Accepted Answer

The conversion factor between kJ and cal is 1 kJ = 239 cal. Therefore, to convert 5.75 kJ to calories, we multiply by 239 to get:
5.75 kJ * 239 cal/kJ = 1372.25 cal
Rounding to two significant figures, we get 1.4 x 10^3 cal or 1.37 x 10^3 cal. The closest answer choice is E, which is 1.37 x 10^3 cal, so that is the best choice.

Question 18

Calculate the mass of Na₂O that can be produced by the reaction of 4.00 g of sodium and 2.00 g of oxygen in the reaction 4 Na + O₂ $\rightarrow$2 Na₂O.

Accepted Answer

The limiting reactant is sodium (Na). The molar mass of Na is 23 g/mol, so 4.00 g of Na is 0.174 mol. The balanced equation shows 4 mol of Na reacts with 1 mol of O2 to produce 2 mol of Na2O. Therefore, 0.174 mol of Na produces 0.087 mol of Na2O. The molar mass of Na2O is 62 g/mol, so 0.087 mol of Na2O is 5.39 g.

Question 19

When C₂H₅Cl(g)is burned in oxygen,chlorine gas is produced in addition to carbon dioxide and water vapor.5145 kJ of heat are released for every four moles of C₂H₅Cl(g)burned.Which of the following correctly represents the thermochemical equation?

Accepted Answer

The thermochemical equation should show the heat released as a negative value, indicating an exothermic reaction.

Question 20

What is the theoretical yield of phosphorus triiodide when 4.50 g of phosphorus is combined with 45.0 g of iodine? The compound is made by the direct combination of the elements.

Accepted Answer

The answer of What is the theoretical yield of phosphorus...

Quiz 10: Quantity Relationships in Chemical Reactions

Ammonium sulfate can be made by the reaction H₂SO₄ + 2 NH₃ $\rightarrow$ (NH₄) ₂SO₄.What quantity of ammonium sulfate will result from the reaction of 5.00 kg of ammonia and 20.0 kg of sulfuric acid?

Formation of two moles of hydrogen chloride gas from the gases hydrogen and chlorine is a reaction for which $\Delta$ H is -185 kJ.Which of the following statements is correct? (i) The reaction is exothermic. (ii) Enthalpy of the system decreases. (iii) Heat is a "product".

How much energy is required to produce 1.00 kg of aluminum by the reaction 2 Al₂O₃(s) + 3 C(s) + 1.97 * 10³ kJ $\rightarrow$ 4 Al(s) + 3 CO₂(g) ?

The metabolism of glucose can be represented by the equation C₆H₁₂O₆(s) + 6 O₂(g) $\rightarrow$ 6 CO₂(g) + 6 H₂O(g) $\Delta$ H = -2.82 *10³ kJ.How many grams of glucose must be metabolized to produce 282 kJ of energy?

Cu₂HgI₄ is prepared according to the equation 2 CuI + HgI₂ $\rightarrow$ Cu₂HgI₄.When 2.00 g of each reactant are used,which one is the limiting reactant?

A typical diet provides about 2000 food Calories per day,or 2000 kilocalories.Calculate the equivalent number of joules.

A typical candy bar contains 281 food Calories,which is 281 kcal.How many kilojoules are contained in one such candy bar?

When 1.00 g of C₆H₁₂O₆(s) is formed during photosynthesis,15.67 kJ of the sun's energy is converted to chemical energy.What is the thermochemical equation for the photosynthesis of glucose?

If the reaction N₂ + 3 H₂ $\rightarrow$ 2 NH₃ is carried out using 1.40 g of N₂ and 0.400 g of H₂,what mass of excess reactant will remain?

The thermochemical equation describing the heat change in the decomposition of limestone,CaCO₃,is given by CaCO₃(s) + 176 kJ $\rightarrow$ CaO(s) + CO₂(g) .What is the heat change that accompanies the decomposition of 25.0 g of limestone?

Convert 357 J to kcal.

The decomposition of potassium chlorate is written as shown below.What energy change occurs when 12.3 g of KClO₃ decompose? 2 KClO₃(s) + 89.6 kJ $\rightarrow$ 2 KCl(s) + 3 O₂(g)

A chemist combines hydrochloric acid with a sodium hydroxide solution,transferring 5.75 kJ of heat.Express this in calories.

Calculate the mass of Na₂O that can be produced by the reaction of 4.00 g of sodium and 2.00 g of oxygen in the reaction 4 Na + O₂ $\rightarrow$ 2 Na₂O.

When C₂H₅Cl(g) is burned in oxygen,chlorine gas is produced in addition to carbon dioxide and water vapor.5145 kJ of heat are released for every four moles of C₂H₅Cl(g) burned.Which of the following correctly represents the thermochemical equation?

What is the theoretical yield of phosphorus triiodide when 4.50 g of phosphorus is combined with 45.0 g of iodine? The compound is made by the direct combination of the elements.

Quiz 10: Quantity Relationships in Chemical Reactions

Ammonium sulfate can be made by the reaction H2SO4 + 2 NH3 →\rightarrow→ (NH4) 2SO4.What quantity of ammonium sulfate will result from the reaction of 5.00 kg of ammonia and 20.0 kg of sulfuric acid?

Formation of two moles of hydrogen chloride gas from the gases hydrogen and chlorine is a reaction for which Δ\DeltaΔ H is -185 kJ.Which of the following statements is correct? (i) The reaction is exothermic. (ii) Enthalpy of the system decreases. (iii) Heat is a "product".

How much energy is required to produce 1.00 kg of aluminum by the reaction 2 Al2O3(s) + 3 C(s) + 1.97 * 103 kJ →\rightarrow→ 4 Al(s) + 3 CO2(g) ?

Δ\DeltaΔ H = +572 kJ for the decomposition of water by the reaction 2 H2O( ) →\rightarrow→ 2 H2(g) + O2(g) .How many grams of water can be decomposed by 5.00 *103 kJ of energy?

The metabolism of glucose can be represented by the equation C6H12O6(s) + 6 O2(g) →\rightarrow→ 6 CO2(g) + 6 H2O(g) Δ\DeltaΔ H = -2.82 *103 kJ.How many grams of glucose must be metabolized to produce 282 kJ of energy?

Cu2HgI4 is prepared according to the equation 2 CuI + HgI2 →\rightarrow→ Cu2HgI4.When 2.00 g of each reactant are used,which one is the limiting reactant?

A typical diet provides about 2000 food Calories per day,or 2000 kilocalories.Calculate the equivalent number of joules.

A typical candy bar contains 281 food Calories,which is 281 kcal.How many kilojoules are contained in one such candy bar?

When 1.00 g of C6H12O6(s) is formed during photosynthesis,15.67 kJ of the sun's energy is converted to chemical energy.What is the thermochemical equation for the photosynthesis of glucose?

If the reaction N2 + 3 H2 →\rightarrow→ 2 NH3 is carried out using 1.40 g of N2 and 0.400 g of H2,what mass of excess reactant will remain?

The thermochemical equation describing the heat change in the decomposition of limestone,CaCO3,is given by CaCO3(s) + 176 kJ →\rightarrow→ CaO(s) + CO2(g) .What is the heat change that accompanies the decomposition of 25.0 g of limestone?

Convert 357 J to kcal.

The decomposition of potassium chlorate is written as shown below.What energy change occurs when 12.3 g of KClO3 decompose? 2 KClO3(s) + 89.6 kJ →\rightarrow→ 2 KCl(s) + 3 O2(g)

Aqueous HCl is added to an aqueous solution of NaOH at 25 °C and the result is shown in the figure below. Which of the following correctly characterizes this reaction?

A chemist combines hydrochloric acid with a sodium hydroxide solution,transferring 5.75 kJ of heat.Express this in calories.

Calculate the mass of Na2O that can be produced by the reaction of 4.00 g of sodium and 2.00 g of oxygen in the reaction 4 Na + O2 →\rightarrow→ 2 Na2O.

When C2H5Cl(g) is burned in oxygen,chlorine gas is produced in addition to carbon dioxide and water vapor.5145 kJ of heat are released for every four moles of C2H5Cl(g) burned.Which of the following correctly represents the thermochemical equation?

What is the theoretical yield of phosphorus triiodide when 4.50 g of phosphorus is combined with 45.0 g of iodine? The compound is made by the direct combination of the elements.

Ammonium sulfate can be made by the reaction H₂SO₄ + 2 NH₃ $\rightarrow$ (NH₄) ₂SO₄.What quantity of ammonium sulfate will result from the reaction of 5.00 kg of ammonia and 20.0 kg of sulfuric acid?

Formation of two moles of hydrogen chloride gas from the gases hydrogen and chlorine is a reaction for which $\Delta$ H is -185 kJ.Which of the following statements is correct? (i) The reaction is exothermic. (ii) Enthalpy of the system decreases. (iii) Heat is a "product".

How much energy is required to produce 1.00 kg of aluminum by the reaction 2 Al₂O₃(s) + 3 C(s) + 1.97 * 10³ kJ $\rightarrow$ 4 Al(s) + 3 CO₂(g) ?

The metabolism of glucose can be represented by the equation C₆H₁₂O₆(s) + 6 O₂(g) $\rightarrow$ 6 CO₂(g) + 6 H₂O(g) $\Delta$ H = -2.82 *10³ kJ.How many grams of glucose must be metabolized to produce 282 kJ of energy?

Cu₂HgI₄ is prepared according to the equation 2 CuI + HgI₂ $\rightarrow$ Cu₂HgI₄.When 2.00 g of each reactant are used,which one is the limiting reactant?

When 1.00 g of C₆H₁₂O₆(s) is formed during photosynthesis,15.67 kJ of the sun's energy is converted to chemical energy.What is the thermochemical equation for the photosynthesis of glucose?

If the reaction N₂ + 3 H₂ $\rightarrow$ 2 NH₃ is carried out using 1.40 g of N₂ and 0.400 g of H₂,what mass of excess reactant will remain?

The thermochemical equation describing the heat change in the decomposition of limestone,CaCO₃,is given by CaCO₃(s) + 176 kJ $\rightarrow$ CaO(s) + CO₂(g) .What is the heat change that accompanies the decomposition of 25.0 g of limestone?

The decomposition of potassium chlorate is written as shown below.What energy change occurs when 12.3 g of KClO₃ decompose? 2 KClO₃(s) + 89.6 kJ $\rightarrow$ 2 KCl(s) + 3 O₂(g)

Calculate the mass of Na₂O that can be produced by the reaction of 4.00 g of sodium and 2.00 g of oxygen in the reaction 4 Na + O₂ $\rightarrow$ 2 Na₂O.

When C₂H₅Cl(g) is burned in oxygen,chlorine gas is produced in addition to carbon dioxide and water vapor.5145 kJ of heat are released for every four moles of C₂H₅Cl(g) burned.Which of the following correctly represents the thermochemical equation?