Concept explainers
Interpretation:
To calculate the average
Concept introduction:
The
The change of enthalpy to form one mole of a substance from its constituent elements when all the substances in the standard form is known as standard enthalpy of formation.
The standard enthalpy of formation
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Chapter 21 Solutions
Chemistry & Chemical Reactivity
- The standard enthalpy of formation of XeF4 is 218 kJ/mol. Use this value and the enthalpy of dissociation of the FF bond to calculate the XeF bond dissociation enthalpy.arrow_forwardwhat is the enthalpy change when 45.7 grams of dinitrogen tetraoxide form? 2 NO2 (g) → N2O4 (g) Delta H = – 57.2 kJ a. +2.61 x 10^3 kJ b. – 28.4 kJ c. + 57.2 kJ d. – 49.7 kJ e. – 57.2 kJ f. +28.4 kJ g. None of these h. +49.7 kJ i. – 2.61 x 10^3 kJarrow_forwardIn a hydrogen molecule, the two hydrogen atoms are held together by a single bond with a bond energy of 436 kJ/mol of hydrogen. In other words, to break the H-H bonds in one mole of molecular hydrogen requires the expenditure of 436 kJ of energy. Using the balanced chemical equation for the formation of water from oxygen and hydrogen (shown above), and interpreting the stoichiometric coefficients as mole amounts, how much energy must be expended in breaking the H-H bonds? kJarrow_forward
- Using the standard enthalpy of formation data, determine which bond is stronger: the P–Cl bond in PCl3(g) or in PCl5(g)?arrow_forwardWhat is the lewis structure for SiO2?arrow_forwardA nonmetal like oxygen forms both ionic and covalent bonds, depending on the identity of the element to which it bonds. What type of bonding is observed in CaO and CO 2? Explain why two different types of bonding are observed.arrow_forward
- How much heat is absorbed (in kilojoules) during production of 127 g of NO by the combination of nitrogen and oxygen?arrow_forwardAnswer the following questions that relate to the chemistry of nitrogen. (a) Two nitrogen atoms combine to form a nitrogen molecule, as represented by the following equation. 2 N(g) ® N2(g) Using the table of average bond energies below, determine the enthalpy change, AH, for the reaction. Average Bond Energy (k) mol-1) Bond N-N 160 N=N 420 N°N 950 (b) The reaction between nitrogen and hydrogen to form ammonia is represented below. N2(g) + 3 H2(g)® 2 NH3(g) AH° = -92.2 kJ Predict the sign of the standard entropy change, AS', for the reaction. Justify your answer. (C) The value of AG° for the reaction represented in part (b) is negative at low temperatures but positive at high temperatures. Explain.arrow_forwardAmmonia is an important chemical used in the production of fertilizer. Industrial production of ammonia from atmospheric nitrogen is difficult because of the energy required to cleave the N-N triple bond. Consider the balanced reaction of ammonia: N2(g) + 3H2(g) → 2 NH3 (9). This reaction has a value of K = 4.3 x 10-2 at 25 °C. Part A Estimate the AH for this reaction using bond energies. Bond Bond Dissociation Energy kcal/mol (kJ/mol) N-H 93 (391) N-N 38 (160) H-H 103 (432) N = N 226 (946) Express your answer as an integer. ΜΕ ΑΣΦ ? kJ/molarrow_forward
- Calculate the lattice energy of AgBr(s) using the following thermodynamic data (all data is in kJ/mol). Ag(s) ΔHsublimation = 265 kJ/mol Ag(g) Ionization energy = 711 kJ/mol Br-Br(g) Bond energy = 173 kJ/mol Br(g) Electron affinity = -345 kJ/mol AgBr(s) ΔH°f = -120 kJ/mol ______________ kJ/molarrow_forwardCalculate the standard enthalpy of formation of the M2O(s) metal oxide (AH+ in kJ/mol) using the following data: Bond dissociation enthalpy of O2(g) = +498 kJ/mol First electron affinity of O = -141 kJ/mol Second electron affinity of O = +744 kJ/mol Enthalpy of sublimation of M + 116 kJ/mol First ionization energy of M = + 463 kJ/mol Lattice enthalpy of M₂O(s) = -2248 kJ/mol Refer to sections 9.4 and 9.5 in the textbook for definitions of ionization energy and electron affinity. Do not use scientific notation for your answer. Do not enter units. Your Answer:arrow_forwardAnswer the questions in the table below about the shape of the borane (BH3) molecule. How many electron groups are around the central boron atom? Note: one "electron group" means one lone pair, one single bond, one double bond, or one triple bond. What phrase best describes the arrangement of these electron groups around the central boron atom? (You may need to use the scrollbar to see all the choices.) (choose one) X G <arrow_forward
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