Concept explainers
Interpretation:To explain the concept to choose a better lubricant having high viscosity.
Concept introduction:
Viscosity: It is a common experience of daily
life that different liquids flow with different speeds, for example, water flows in greater speed than glycerol. Obviously some sort of internal friction is operating which checks the flow of liquids and which varies from liquid to liquid. This internal friction in liquids is primarily due to intermolecular force of attraction between the molecules. If we have a laminar flow of liquid in a tube, then the velocity of the layer just in touch with the side of the tube is zero and it increases as we proceed towards the center of the tube as shown in the figure. Thus, there exists velocity gradient between the different layers of the liquids.
Due to greater intermolecular attraction between the molecules of liquids, the molecules moving in any layer will tend to impede the movement of the molecules in the adjacent faster moving layer as a result the velocity of the molecules in the faster layer decreases. Unless this decrease is prevented by applying a force along the layer in the forward direction, the velocity of the faster moving layer will go on decreasing and ultimately it will become zero. At this stage the liquid will stop flowing.
- Lubricant: A lubricant is an organic substance having high molecular weight, which is needed to reduce the interactions between surfaces of two material and control the generation of heat due to the movement of the surfaces. The molecule must have high viscosity for the effective application. It has a wide application in field of motors in vehicle, pump and many a field.
Want to see the full answer?
Check out a sample textbook solutionChapter 8 Solutions
Chemistry for Engineering Students
- Bond Enthalpy When atoms of the hypothetical element X are placed together, they rapidly undergo reaction to form the X2 molecule: X(g)+X(g)X2(g) a Would you predict that this reaction is exothermic or endothermic? Explain. b Is the bond enthalpy of X2 a positive or a negative quantity? Why? c Suppose H for the reaction is 500 kJ/mol. Estimate the bond enthalpy of the X2 molecule. d Another hypothetical molecular compound, Y2(g), has a bond enthalpy of 750 kJ/mol, and the molecular compound XY(g) has a bond enthalpy of 1500 kJ/mol. Using bond enthalpy information, calculate H for the following reaction. X2(g)+Y2(g)2XY(g) e Given the following information, as well as the information previously presented, predict whether or not the hypothetical ionic compound AX is likely to form. In this compound, A forms the A+ cation, and X forms the X anion. Be sure to justify your answer. Reaction: A(g)+12X2(g)AX(s)The first ionization energy of A(g) is 400 kJ/mol. The electron affinity of X(g) is 525 kJ/mol. The lattice energy of AX(s) is 100 kJ/mol. f If you predicted that no ionic compound would form from the reaction in Part e, what minimum amount of AX(s) lattice energy might lead to compound formation?arrow_forwardWhich one of the following ionic compounds has the smallest lattice formation enthalpy (lattice energy) thus making it the least favorable to form a stable lattice? A) MgF₂ B) Na₂O C) CaO D) LiBrarrow_forward16). Using the thermochemical data below calculate the lattice energy for the formation of Na₂O. Na(s) → Na(g) 107.3 kJ/mol Na(g) → Na (g) + 1 e - 495.9 kJ/mol -418 kJ/mol 249.1 kJ/mol -141 kJ/mol -1484.5 kJ/mol 2 Na(s) + O₂(g) →→→ Na₂O(s) 1/2 O₂(g) → 0(g) O(g) + 1 e→O(g) O(g) +1e0²(g)arrow_forward
- Carbon naturally occurs in two forms: diamond and graphite. Why do these two forms have very different properties? The key difference is that diamonds have other elements bonded within their structure. The differences are explained by the number of covalent and ionic bonds within each substance. The differences are explained by the density: graphite is very high and diamond is much lower. The differences are explained by how the carbon atoms within each substance are covalently bonded together.arrow_forward10. You're preparing for a camping trip. you see two different stoves you can pack for your trip to do all your cooking. Which fuel would you prefer to carry? One stove uses fuel propane. The other stove uses naphtha (hexane) fuel. Start by writing a balanced combustion equation for both of these reactions. Use either standard enthalpies of formation or bond energies to determine the enthalpy changes for the combustion of these two fuels. Then suggest which stove, the one that uses propane or the one that uses naphtha, would you recommend to pack for your camping trip? Explain. (You may need more space for your response).arrow_forwardA hydrated salt is one in which water molecules are suspended in the crystal lattice structure of the salt. Upon heating what happens to these water molecules? What change can be expected in the structure and appearance of the salt?arrow_forward
- What is lattice energy? A.Lattice energy is ionization energy + electron affinity/2 B.Lattice energy is the standard enthalpy of formation of an ionic solid C.Lattice energy is the energy needed for an ionic solid to dissolve D Lattice energy is the energy of formation of one mole of ionic solid from gaseous ionsarrow_forwardEstimate the ionic radius of Cs+. The lattice energy of CsCl is 633 kJ/mol. For CsCl the Madelungconstant, M, is 1.763, and the Born exponent, n, is 10.7. The ionic radius of Cl– is known to be 1.81 Åarrow_forwardWhich of the equations shown in the image respresent the lattice A) Ca(s)+ Br2(g) → CaBr2(s) energy? B) Ca(g) +Br2(g) → CaBr2(s) C) Ca²*(g) + 2 Br´(g) → CaBr2(s) D) Ca2*(g) + Br22(g) → CaBr2(s)arrow_forward
- Calculate the lattice energy of magnesium sulfide from the data given below. Mg(s) Mg(g) AE 148 kJ/mol Mg2g) 8S(g) AE 2232 kJ/mol 2e AE 2186 kJ/mol Mg(g) S8(s) Sig) 2eSg) AE= 450 kJ/mol 8Mg(s)S8(s) -» 8M9S(s) AE = -2744 kJ/mol Mg2+(g) S2g) MgS(s) AElattice = ?arrow_forwardWhich of the compounds has higher lattice energy? Explain your answer. i) Na2O or Na2Farrow_forwardWhich ionic solid do you expect to have the most negative lattice energy? MgO O CaCl2 O CaS O NaClarrow_forward
- Chemistry by OpenStax (2015-05-04)ChemistryISBN:9781938168390Author:Klaus Theopold, Richard H Langley, Paul Flowers, William R. Robinson, Mark BlaserPublisher:OpenStaxChemistry: The Molecular ScienceChemistryISBN:9781285199047Author:John W. Moore, Conrad L. StanitskiPublisher:Cengage LearningIntroductory Chemistry: A FoundationChemistryISBN:9781337399425Author:Steven S. Zumdahl, Donald J. DeCostePublisher:Cengage Learning
- Chemistry for Engineering StudentsChemistryISBN:9781337398909Author:Lawrence S. Brown, Tom HolmePublisher:Cengage LearningChemistry & Chemical ReactivityChemistryISBN:9781133949640Author:John C. Kotz, Paul M. Treichel, John Townsend, David TreichelPublisher:Cengage LearningChemistry & Chemical ReactivityChemistryISBN:9781337399074Author:John C. Kotz, Paul M. Treichel, John Townsend, David TreichelPublisher:Cengage Learning