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|1 List the intermolecular and intramolecular forces. Why is the term |2 Identify intramolecular and intermolecular forces for each of the |

|intramolecular sometimes a misnomer? |following. Predict the order in which they would melt. |

| |GeH4 SiH4 SnH4 CH4 |

|3 A. Identify intramolecular and intermolecular forces for each of the |4 Does the following diagram best describe a crystalline solid, liquid, |

|following. The electronegativities of Se, S, and Te are all within 0.5 of |or gas? Explain. |

|each other which is quite small. Predict the order in which they would melt.|[pic] |

|When these substances melt, are intermolecular or intramolecular forces | |

|being broken? | |

| | |

|H2Te H2S H2O H2Se | |

| | |

|B. If a mixture contained all four of these substances in the liquid phase, | |

|which would be the first to distill? Which would be the last? How does this | |

|list compare with your list in part A? Why? | |

|5 The following are in order; do they go in order of increasing or |6 In the Lewis structure shown below, A, D, E, Q, X, and Z represent |

|decreasing melting points? Use intramolecular and intermolecular forces to |elements in the first two periods of the periodic table. Identify all |

|thoroughly justify the order. |six elements and explain how you determined the identity. |

| |[pic] |

|C, BaCl2, HF, CO, Ne, H2 | |

| | |

|What type of solid would each substance form? Are any solid types not | |

|represented? If so, list them and give an example. | |

|7 Which of the following molecules can form hydrogen bonds with other |8 As the intermolecular attractive forces between molecules increase in|

|molecules of the same kind? Draw two molecules for each selection and |magnitude, do you expect each of the following to increase or decrease |

|indicate Hydrogen bonding. Circle covalently-bonded hydrogens that cannot |in magnitude? |

|H-bond. |*boiling point, freezing point, viscosity, surface tension, adhesion, |

| |cohesion, capillary action, vapor pressure |

|CH3F CH3NH2 CH3OH CH3Br | |

|9 What kinds of attractive forces exist between particles in molecular |10 The state of aggregation of solids can be described as belonging to |

|solids, network solids, ionic solids, and metallic solids (discuss |the following four types: |

|electrons)? |(1) ionic (3) network |

| |(2) metallic (4) molecular |

|A white substance melts with some decomposition at 730°C. As a solid, it is |For each of these types of solids, sketch a diagram of the solid and |

|a nonconductor of electricity, but it dissolves in water to form a |indicate the kinds of particles that occupy the lattice points and |

|conducting solution. Which type of solid might the substance be? How do you |identify forces among these particles. How could each type of solid be |

|know? |identified in the laboratory? |

|11 Identify the type of solid the representation below depicts. List all |12 The diagram uses a polar stationary phase and a nonpolar mobile |

|the properties of this solid type that you know. Use features of the diagram|phase. Given the following solutions, identify which would be A and |

|to explain why this solid has two properties you listed. |which would be B. |

|[pic] |Br2____&NH3_____ |

| |CH3Cl___&CH4____ |

| |ethane_____ðanol_____ |

| | |

| |Calculate the Rf values |

| |for A and B. |

|13 Lab equipment: beaker, scale, graduated cylinder, weigh boat, volumetric |14 For practice: For the following: draw the lewis structure (with |

|flasks (100mL and 500mL), water, solid NaCl, Erlenmeyer flask |formal charges), name the shape according to modern bonding theory, |

| |identify angles, and indicate polarity and hybridization. |

|A. The equipment above is available to you. Thoroughly explain how to make | |

|100 mL of a 2.5M solution of NaCl. Show any calculations needed. |Explain similarities and differences. |

| |phosphite and phosphate |

|B. Explain how to dilute the solution made in part A into 500mL of 1.0M NaCl| |

|solution. Show any calculations needed. | |

Answers:

|1. inter=London dispersion, dipole-dipole, hydrogen bond; intra=covalent, metallic, ionic; |2. lowest: CH4, SiH4, GeH4,SnH4 (if you assume that |

|intramolecular is a misnomer because only the individual particles of covalent substances are called |the first three are covalent and have only LDF, they |

|molecules (formula unit is used for ionic and metallic has no name for individual parts) |increase in molecular weight and therefore increase |

| |strength of LDF; the last one is ionic) |

|3. This one is tricky ;) You need to know that the electronegativities of S, Se, and Te are pretty |4. liquid: , no repeating structure like a crystalline |

|close to each other…. |solid, not spaced out enough to be a gas (although you |

| |could make an argument for gas, liquid is still the |

|A. lowest: H2S, H2Se, H2Te, H2O (the first three are all dipole-dipole and LDF, but their closeness in|best answer) |

|electronegativity means that the increasing molar mass makes the larger ones have a higher LDF forces | |

|and a higher meting point; H-bonding in water makes it highest), intermolecular forces are being | |

|broken when these substances melt. | |

| | |

|B. H2S would distill first; water would distill last; the order is the same because the forces that | |

|hold these in the solid state are the same forces holding them in the liquid state. | |

|5. they decrease; lowest: H2, Ne, CO, HF, BaCl2, C (LDF, stronger LDF because it has more electrons, |6. A is fluorine, D is carbon, E is oxygen, Q is |

|dipole-dipole, H-bond, ionic, network; metallic is missing: Cu, Zn, are examples) ( if two things have|nitrogen, Z/X are hydrogen |

|the same forces, you must explain why they are different to get full credit | |

|7. CH3NH2 and CH3OH can do H-bonding because they have hydrogen attached to N/O/F (see below). |8. Everything increases except vapor pressure (which |

|Although CH3F has hydrogen and fluorine, they are not attached to each other. CH3Br doesn’t have NOF, |decreases) |

|so it cannot do hydrogen bonding. | |

|[pic] | |

| | |

|[pic] | |

|9. Molecular (intermolecular), network (covalent, electrons are being shared), ionic (intramolecular |10. USE YOUR FOLDABLE TO CHECK YOUR DRAWINGS. |

|electrostatic attractions, electrons are trapped onto ions), metallic (nondirectional covalent, | |

|intramolecular, sea of electrons); the unknown is most likely an ionic solid |Lattice points are occupied by: |

| |-Molecular (covalent compounds or nonmetal atoms) |

| |-network (carbon, silicon, or SiC or SiO2) |

| |-metallic (the core electrons and nuclei of metal |

| |atoms, valence electrons have been removed) |

| |-ionic (ions) |

| | |

| |USE YOUR FOLDABLE TO CHECK YOUR ANSWER TO HOW THESE |

| |SUBSTANCES COULD BE IDENTIFIED IN THE LAB. |

|11. The solid is a metal. Metals have low vapor pressures, conduct heat and electricity, and mare |12. Since the mobile phase is nonpolar, nonpolar |

|malleable/ductile. |molecules should travel with the nonpolar solute (where|

|Good conductor of heat/electricity-The valence electrons are delocalized and relatively free to move |they are more soluble/attracted to) rather than |

|Malleable/Ductile-Deforming the solid doesn’t change the environment immediately surrounding each |sticking to the polar stationary phase. |

|metal core | |

| |Br2_A__&NH3_B___ |

| |CH3Cl_B_&CH4_A__ |

| |ethane__A__ðanol__B__ |

| | |

| |Rf values: |

| |[pic] |

|13. |14. phosphite has -1 FC on all three O atoms, 107, sp3,|

|A. First calculate the mass of NaCl needed: |polar; phosphate has 1 double bond and resonance, sp3, |

|[pic] |107, polar |

|Then, measure 14.61 grams of NaCl using a weigh boat and a scale. Then, place this in a 100mL | |

|volumetric flask and fill partially with distilled water. Wait for the solid to completely dissolve. | |

|Add water until the bottom of the meniscus meets the line on the neck of the volumetric flask. Stir to| |

|combine. | |

| | |

|B Calculate the volume of the 2.5 Molar solution needed. | |

|M1V1=M2V2 | |

|(2.5 M) V1 = (1.0 M)(500mL) (if V2 is in mL, V1 will also be; liters could be used as well) | |

|V1 = 200 mL | |

| | |

|Measure 200mL of the 2.5 M NaCl stock solution. Place this in a volumetric flask. Fill partially with | |

|distilled water. Stir. Add water until the bottom of the meniscus meets the line on the neck of the | |

|volumetric flask. Stir to combine. [Note: if this had been the dilution of an acid, the acid would | |

|have been added to the water; since this is not an acid, the order that I combine the 200mL of | |

|solution and the 300mL of water doesn’t matter. | |

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