chemistry

According to the equation below, what is the enthalpy change when 400.0 g of propane is burned in excess oxygen?C3H8 (g) + 5O2 (g) ) → 3CO2 (g) + 4H2O (l) ΔH = -2221kJ

- 20.19 MJ

Given:H2S(g)+3F2(g) → SF4(g)+2HF(g)ΔHbond(H-S)=+347 kJ/molΔHbond(F-F)=+155 kJ/molΔHbond(S-F)=+327 kJ/molΔHbond(H-F)=+567 kJ/mol Determine the enthalpy of the gas phase reaction (ΔH).

-1283 kJ/mol

Calculate ΔHΔH for the reaction Sn(s)+H2O(g)→SnO(s)+H2(g)Sn(s)+H2O(g)→SnO(s)+H2(g) given the following thermochemical equations: Sn(s)+O2(g)2SnO(s)+O2(g)2H2(g)+O2(g)→→→SnO2(s)2SnO2(s)2H2O(g)ΔH1ΔH2ΔH3===−581.0kJ−292.9kJ−483.6kJ

-192.8

Given:C2H4(g) +3O2(g)↔2CO2(g)+2H2O(g)ΔHf(C2H4)= 52.5 kJ/molΔHf(H2O)=-285.8 kJ/molΔ H0rxn=-1411.1 kJ/mol.

-393.5 kJ/mol

If the heat of formation of NH3(g)NH3(g) is −−46 kJ/molkJ/mol, which of the following thermochemical equations is correct?

12N2(g)+32O2(g)→NH3(g)ΔH=−46kJ12N2(g)+32O2(g)→NH3(g)ΔH=−46kJ

When 1.00 mole of NH4NO3 dissolves in water, the enthalpy change is ΔH = + 25.7 kJ. What is the enthalpy change if 17.5 grams of NH4NO3 are dissolved in water?

5.62 kJ

How much heat is needed to raise the temperature of a 5.0 gram block of aluminum from 22.0° C to 37.0° C?

68 J

The specific heat of silver (Ag) is 0.245 J/ºC g. Determine the energy required to raise the temperature of 350. g of Ag from 293 K to 400 K.

9.17 kJ

Choose the correct classification of chemical energy process for the reaction shown below.N2 (g) + O2 (g) + energy (heat) → 2NO (g)

Endothermic process

What is the first law of thermodynamics?

Energy can be converted from one form to another, but it is neither created nor destroyed.

Which statement below best describes the fundamental principle of thermochemistry?

Energy is released when chemical bonds are formed; energy is consumed when chemical bonds are broken.

Many portable gas heaters and grills use propane, C3H8(g)C3H8(g). Using enthalpies of formation, calculate the quantity of heat produced when 18.0 gg of propane is completely combusted in air under standard conditions. Assume that liquid water is forming.

Q=906kJ C3H8(g)+5O2(g)→3CO2(g)+4H2O(l)

When solutions containing silver ions and chloride ions are mixed, silver chloride precipitates: Ag+(aq)+Cl−(aq)→AgCl(s),ΔH=−65.5kJ a)Calculate ΔHΔH for the production of 0.440 mol of AgClAgCl by this reaction. b)Calculate ΔH for the production of 7.50 g of AgCl c)Calculate ΔH when 9.29×10−4mol of AgCl dissolves in water.

a) -28.8kJ b)-3.43kJ c) 60.5kJ

a) What is the value of the standard enthalpy of formation of an element in its most stable form? b)Write the chemical equation for the reaction whose enthalpy change is the standard enthalpy of formation of fructose, C6H12O6(s), ΔH∘f∘[C6H12O6]

a) 0 b)6C(s)+6H2(g)+3O2(g)→C6H12O6(s)

Consider the following hypothetical reactions: A→B ΔH=+25kJ B→C ΔH=+64kJ a)Use Hess's law to calculate the enthalpy change for the reaction A→C B)

a) 89kJ b)

2CH3OH(g)→2CH4(g)+O2(g),ΔH=+252.8kJ a)Is this reaction exothermic or endothermic? b)Calculate the amount of heat transferred when 29.0 g of CH3OH(g) is decomposed by this reaction at constant pressure. c) For a given sample of CH3OH, the enthalpy change during the reaction is 82.6 kJkJ . What mass of methane gas is produced? d)How many kilojoules of heat are released when 38.2 gg of CH4(g) reacts completely with O2(g) to form CH3OH(g) at constant pressure?

a) endothermic b)114 kJ c)10.5g d)304kJ

a)Write an equation that expresses the first law of thermodynamics in terms of heat and work. b) Under what conditions will the quantity q be a negative number and the quantity ww be a positive number?

a) ΔE=q+w b) q is negative when the system loses heat to surroundings, ww is positive when the surroundings does work on the system.

a) Calculate ΔE, if q=q= 0.762 kJkJ and w=w= -820 JJ . b) Calculate ΔE, if a system releases 66.5 kJ of heat to its surroundings while the surroundings do 41.0 kJ of work on the system. c)Identify whether each process is endothermic or exothermic: the process from Part A: q= 0.762 kJkJ and w= -820 JJ ; the process from Part B: a system releases 66.5 kJ of heat to its surroundings while the surroundings do 41.0 kJ of work on the system.

a) −5.8×10−2kJ b)-26kJ c)The process from Part A is endothermic and the process from Part B is exothermic

The specific heat of ethanol, C2H5OH(l), is 2.44 J/(g⋅K). a)How much heat is needed to raise the temperature of 72.0 g of ethanol from 10.6 ∘C to 24.6 ∘C? b)Which will require more heat, increasing the temperature of 1 mol of C2H5OH(l) by a certain amount or increasing the temperature of 1 mol of H2O(l) by the same amount?

a)2460J b)greater than the molar heat capacity of water, thus increasing the temperature of 1 molmol of C2H5OH(l)

A 1.800-gg sample of solid phenol (C6H5OH(s)) was burned in a bomb calorimeter, which has a total heat capacity of 11.66 kJ/∘C. The temperature of the calorimeter plus its contents increased from 21.36∘C∘C to 26.37∘C∘C. a)Write a balanced chemical equation for the reaction that takes place in the bomb calorimeter. b)What is the heat of combustion per gram of phenol? c)What is the enthalpy per mole of phenol?

a)C6H5OH(s)+7O2(g)→6CO2(g)+3H2O(l) b)-32.5 kJ/g c)-3050kJ/mol

Consider the following reaction: 2Mg(s)+O2(g)→2MgO(s),ΔH=−1204kJ a) Is this reaction exothermic or endothermic? b)Calculate the amount of heat transferred when 3.52 gg of Mg(s) reacts at constant pressure. c) How many grams of MgO are produced during an enthalpy change of -235 kJkJ ? d)how many kilojoules of heat are absorbed when 40.1 gg of MgO(s) is decomposed into Mg(s)Mg(s) and O2(g)O2(g) at constant pressure?

a)exothermic b)-87.2kJ c) 15.7g d)599kJ

The overall enthalpy change for a reaction

depends only on the amount of matter that undergoes the change and on the initial state of the reactants and the final state of the products

During an exothermic process,

heat flows from the system to the surroundings

ΔH f°

is usually reported at 298K

In which of the following processes is Δ H positive if carried out under atmospheric pressure?

melting of ice

If we define the system as the gases inside the cylinder, which of the following best describes the signs of q, w, and ΔE for this reaction?

q>0, w<0, the sign of ΔE cannot be determined from the information given

Combustion reactions are most conveniently studied

using constant-volume calorimetry

For a hypothetical reaction X(g)→Y(g) you are told that the enthalpy of Y(g) is greater than that of X(g). Which of the following statements is false?

ΔH for the reaction is negative.

Estimate the ∆H value when hydrogen reacts with oxygen per the following chemical reaction:2 H‒H(g) + O=O(g) → 2 H‒O-H(g)

−485 kJ