Calculate the change in enthalpy for the given reaction

Question

Assignment:

1- Calculate the change in enthalpy for the reaction. (Use 1.0g/mL as the density of the solution and 4.18J/g^oC as the specific heat capacity.)?

Instant cold packs, often used to ice athletic injuries on the field, contain ammonium nitrate and water separated by a thin plastic divider. When the divider is broken, the ammonium nitrate dissolves according to the following endothermic reaction:
NH₄NO₃(s)→NH₄+(aq)+NO₃- (aq)

In order to measure the enthalpy change for this reaction, 1.25 g of NH4NO3 is dissolved in enough water to make 25.0 mL of solution. The initial temperature is 25.8^oC and the final temperature (after the solid dissolves) is 21.9^oC .

2- When 0.501g of biphenyl (C₁₂H₁₀ ) undergoes combustion in a bomb calorimeter, the temperature rises from 25.2^oC to 29.4^oC. Find ΔE rxn for the combustion of biphenyl in kJ/mol biphenyl. The heat capacity of the bomb calorimeter, determined in a separate experiment, is 5.86 kJ/^oC .

3- What is the enthalpy for reaction 1 reversed? Express your answer numerically in kilojoules per mole. reaction 1 reversed: N₂O₄ →N ₂+2O₂

4- Calculate the enthalpy of the reaction

2NO(g)+O₂(g)→2NO₂(g) given the following reactions and enthalpies of formation:
1. 1/ 2 N₂ (g)+O₂(g)→NO₂(g), ΔH^oA =33.2 kJ
2. 1/ 2 N₂(g)+ 1/ 2O₂(g)→NO(g), ΔH^oB =90.2 kJ
Express your answer with the appropriate units.

5- Calculate the enthalpy of the reaction
4B(s)+3O₂ (g)→2B₂O₃(s)
given the following pertinent information:

1. B2O₃(s)+3H₂O(g)→3O₂(g)+B₂H₆(g), ΔHoA =+2035 kJ
2. 2B(s)+3H ₂ (g)→B2H6(g), ΔHoB =+36 kJ
3. H₂ (g)+ 1₂O₂ (g)→H2O(l), ΔHoC =-285 kJ
4. H₂O(l)→H₂O(g), ΔHoD =+44 kJ
Express your answer with the appropriate units.

6- Ozone, O₃ is destroyed when ClO levels are high. ClO is likely formed from the decomposition of chlorofluorocarbons (CFCs) in sunlight.

Standard enthalpies of formation for selected substances are given in the table below.

Substance	ΔHof (kJ/mol )
ClO(g)	101.0
ClO2(g)	102.0
O(g)	247.5
O2(g)	0
O3(g)	142.3

A- Calculate the standard enthalpy change of the reaction
ClO(g)+O₃(g)→ClO₂(g)+O₂(g) Express your answer in kilojoules using four significant figures.

B- Calculate the standard enthalpy change of the reaction
ClO₂(g)+O(g)→ClO(g)+O₂(g) Express your answer in kilojoules using four significant figures.

C- Add the following reactions together:
ClO(g)+O₃(g)ClO₂(g)+O(g) → → ClO₂(g)+O₂(g)ClO(g)+O₂(g) Identify which species cancel and which do not.

7- Consider the reaction N₂(g)+3H₂(g)→2NH₃(g), ΔH =-92.3kJ
What will ΔH be for the reaction if it is reversed?
Express your answer with appropriate units.

8- calculate the change in enthalpy for Reaction 2.

Reaction 1: C₃H₈ (g)+5O₂ (g)→3CO₂ (g)+4H₂O(g), ΔH 1 =-2043 kJ
Reaction 2: 4C₃H₈(g)+20O₂(g)→1₂CO₂(g)+1₆H₂O(g), ΔH 2 =?

Express your answer to four significant figures and include the appropriate units.

9- calculate the reaction enthalpy, ΔH , for the following reaction:

CH₄(g)+2O₂(g)→CO₂(g)+2H₂O(l)

Use the series of reactions that follow:

1. C(s)+2H₂ (g)→CH₄(g), ΔH =-74.8 kJ .
2. C(s)+O₂(g)→CO₂ (g) , ΔH =-393.5 kJ .
3. 2H₂ (g)+O₂ (g)→2H₂O(g) , ΔH =-484.0 kJ .
4. H₂O(l)→H₂O(g), ΔH =44.0 kJ .
Express your answer with appropriate units.

10- Calculate the standard enthalpy change for the reaction
2A+B?2C+2D
Use the following data:

Substance	ΔH o f (kJ/mol)
A	-267
B	-383
C	191
D	-481

Express your answer to three significant figures and include the appropriate units.

11- What is ΔH^o rxnfor the following chemical reaction?
H₂O(l)+CCl₄(l)→COCl₂(g)+2HCl(g)
You can use the following table of standard heats of formation (ΔH^of ) to calculate the enthalpy of the given reaction.

Element/ Compound	Standard Heat of Formation (kJ/mol)	Element/ Compound	Standard Heat of Formation (kJ/mol)
H(g)	218	N(g)	473
H2(g)	0	O2 (g)	0
CCl4 (l)	-139.5	O(g)	249
H2O(l)	-285.8	HCl(g)	-92.30kJ
C(g)	71	COCl2 (g)	-218.8kJ
C(s)	0	HNO3 (aq)	-206.6

Express the standard enthalpy of reaction to three significant figures and include the appropriate units.

12- The combustion of ethene, C₂H₄ , occurs via the reaction
C₂H₄ (g)+3O₂ (g)→2CO₂ (g)+2H₂O(g)

with heat of formation values given by the following table:

Substance	ΔH o f (kJ/mol)
C2H4 (g)	52.47
CO2 (g)	-393.5
H2O(g)	- 241.8

Calculate the enthalpy for the combustion of ethene.
Express your answer to four significant figures and include the appropriate units.

13- For which of the following reactions is ΔH o rxn equal to ΔH o f of the product(s)?
You do not need to look up any values to answer this question.
Check all that apply.
Check all that apply.

	Na(s)+ 12F2 (l)→NaF(s)
	2H2 (g)+O2 (g)→2H2O(g)
	H2(g)+12O2(g)→H2O(g)
	H2O2(g)→12O2(g)+H2O(g)
	2Na(s)+F2 (g)→2NaF(s)
	Na(s)+ 12F2 (g)→NaF(s)

14- What is the balanced chemical equation for the reaction used to calculate ΔH^of of BaCO₃ (s) ? If fractional coefficients are required, enter them as a fraction (i.e. 1/3). Indicate the physical states using the abbreviation (s ), (l ), or (g ) for solid, liquid, or gas, respectively. Use (aq ) for aqueous solution.
Express your answer as a chemical equation

The standard enthalpy of formation (ΔH^of ) is the enthalpy change that occurs when exactly 1 mol of a compound is formed from its constituent elements under standard conditions. The standard conditions are 1 atm pressure, a temperature of 25^oC , and all the species present at a concentration of 1 M . A "standard enthalpies of formation table" containing ΔH o f values might look something like this:

Substance	ΔH o f
H(g)	218 kJ/mol
H2 (g)	0 kJ/mol
Ba(s)	0 kJ/mol
Ba2+ (aq)	- 538.4 kJ/mol
C(g)	71 kJ/mol
C(s)	0 kJ/mol
N(g)	473 kJ/mol
O2 (g)	0 kJ/mol
O(g)	249 kJ/mol
S2 (g)	129 kJ/mol

15- nitrogen triiodide, NI₃ , and determine which of the following statements are correct.
Check all that apply.

NI₃ is a highly stable compound when it is dry.

In this reaction, heat is absorbed from the surroundings.

The enthalpy of NI₃ is greater than the enthalpy of the decomposition products.

In this reaction, iodine is produced as one of the products.

The decomposition of NI₃ is an exothermic reaction.

16- The decomposition of NI 3 to form N₂ and I₂ releases - 290.0 kJ of energy. The reaction can be represented as
2NI₃(s)→N₂(g)+3I₂(g),ΔH rxn =-290.0 kJ

Find the change in enthaply when 19.0g of NI 3 decomposes.
Express your answer to three significant figures and include the appropriate units.

17-Consider the exothermic reaction
2C₂ H₆ (g)+7O₂ (g)→4CO₂ (g)+6H₂O(g)

Calculate the standard heat of reaction, or ΔH^o rxn , for this reaction using the given data. Also consider that the standard enthalpy of the formation of elements in their pure form is considered to be zero.

 

Reactant or product	ΔHof (kJ/mol)
C2H6 (g)	-84.7
CO2(g)	-393.5
H2O(g)	-241.8

Express your answer to four significant figures and include the appropriate units.

17- Enthalpy H is a measure of the energy content of a system at constant pressure. Chemical reactions involve changes in enthalpy, ΔH which can be measured and calculated:ΔH rxn^o =∑ products mΔH f^o -∑ reactants nΔH f^o where the subscript "rxn" is for "enthalpy of reaction" and "f" is for "enthalpy of formation" and m and n represent the appropriate stoichiometric coefficients for each substance.The following table lists some enthalpy of formation values for selected substances.
Substance ΔH f^o (kJ/mol)

Substance	ΔH f o (kJ/mol)
HCl(g)	-92
Al(OH)3 (s)	-1277
H2O(l)	-285.8
AlCl3 (s)	-705.6
H2O(g)	-241.8

a- Determine the enthalpy for this reaction:Al(OH)₃(s)+3HCl(g)→AlCl₃(s)+3H₂O(l) Express your answer in kilojoules per mole to four significant figures.

b- Consider the reaction 2Al(OH)₃(s)→Al2O₃ (s)+3H₂O(l) with enthalpy of reaction
ΔH rxn^o =21.00kJ/mol. What is the enthalpy of formation of Al₂O₃ (s)? Express your answer in kilojoules per mole to four significant figures.

18- Use the data below to answer the questions.

Substance	ΔH o f (kJ/mol)
C(g)	718.4
CF4 (g)	- 679.9
CH4 (g)	- 74.8
H(g)	217.94
HF(g)	- 268.61

Keep in mind that the enthalpy of formation of an element in its standard state is zero.

a- Suppose that 0.610mol of methane, CH₄ (g) is reacted with 0.760mol of fluorine, F₂(g) , forming CF₄(g) and HF(g) as sole products. Assuming that the reaction occurs at constant pressure, how much heat is released?Express your answer to three significant figures and include the appropriate units.