front 1 what is dispersion force | back 1 present in all molecules and atoms and increase with increasing molar mass; always weak in small molecules |
front 2 why does having a larger electron cloud result in a greater dispersion force | back 2 because the electrons are held less tightly by the nucleus and therefore polarize easier |
front 3 why do boiling points increase with increase strength of intermolecular forces | back 3 because more thermal energy is required to separate the particles from the liquid state into the gas state |
front 4 what is dipole-dipole force | back 4 it exists in all molecules that are polar has electron rich and electron deficient regions |
front 5 what has higher melting and boiling points | back 5 polar molecules |
front 6 what is miscibility | back 6 the ability to mix without separating into two states |
front 7 what is a permanent dipole | back 7 molecules, such as acetone, are attracted to one another via dipole-dipole interactions |
front 8 what is a hydrogen bond | back 8 strong attraction between the H atom and F, O, or N |
front 9 what is the strongest intermolecular force that occurs in pure substances | back 9 hydrogen bonds |
front 10 what is a ion-dipole force | back 10 occurs when an ionic compound is mixed with a polar compound; very strong with aqueous solutions |
front 11 Pick the compound with the highest boiling point in each pair. Explain your reasoning A) CH3OH or CH3SH B) CH3OCH3 or CH3CH3COH C) CH4 or CH3CH3 | back 11 A) CH3OH - hydrogen bonding B) CH3CH2OH- hydrogen bonding C) CH3Ch3- bigger mass |
front 12 In each pair of compounds, pick the one with the higher vapor pressure at a given temp a) CH or CH3Cl b) CH3CH2CH2OH or CH3OH c)CH3OH or H2O | back 12 a) CH- smaller mass b) CH3OH- smaller mass c) H2CO - lacks hydrogen bonding |
front 13 Which compound would you expect to have a greater surface tension: acetone or water. Explain | back 13 Water because surface tension increases with increasing intermolecular forces |
front 14 Water in a glass tube that contains grease or oil residue displays a flat meniscus whereas water in a clean glass tube displays a concave meniscus. Explain | back 14 water experiences adhesive forces with glass that are stronger than its cohesive forces, causing it to climb the surface of a glass tube. water does not experience strong intermolecular forces with oil, so if the tube is coated in oil, the water's cohesive forces will be greater and it will not be attracted to the surface of the tube |
front 15 which evaporates more quickly: 55 ml of water in a beaker with a diameter of 4.5 cm of 55 ml of water in a dish with a diameter of 12 cm | back 15 the water in the 12 cm dish will evaporate more quickley because the bigger the surface area, the more molecules to obtain enough energy at the surface and break free |
front 16 which evaporates more quickly: 55 ml of water in a beaker or 55 ml of acetone in a beaker | back 16 acetone because it is more volatile than water and acetone has the higher vapor pressure bc it is lighter |
front 17 how much energy is released when 65.8 g of water freezes | back 17 22 kj |
front 18 an 8.5 g ice cube is placed into 225 g of water. Calculate the temp change in the water upon the complete melting of the ice | back 18 2.7 C |
front 19 How much ice (in grams) would have to melt to lower the temp of 352 ml of water from 25 C to 5 C (assume the density of water is 1 g/ml) (heat of fusion is 6.02 kJ/mol) | back 19 87.99 grams |
front 20 how much heat (in kj) is evolved in converting 1 mol of steam at 145 C to ice at -50 C. The heat capacity of steam is 2.01 J/g *C, and that of ice is 2.09 J/g*C (heat of fusion for steam is 2230, heat of fusion for water is 334, heat of fusion for ice is 6.02) | back 20 51.2 kj |
front 21 what has the smallest surface area | back 21 sphere |
front 22 what is viscosity | back 22 the resistance of a liquid to flow |
front 23 where is viscosity greater in | back 23 substances with strong intermolecular forces because if molecules are more strongly attached to each other, they do not flow around each other as freely |
front 24 what is capillary action | back 24 the ability of a liquid to flow against gravity up a narrow tube; like taking a blood sample |
front 25 what is cohesive forces | back 25 the attraction between molecules in a liquid; cause the liquid to stay together |
front 26 what is adhesive forces | back 26 the attraction between those molecules and the surface of the tube; causes liquids to spread out over the surface of the tube |
front 27 what is vaporization | back 27 the process by which thermal energy can overcome intermolecular forces and produce a state change from a liquid to a gas |
front 28 why does evaporation take faster than condensation | back 28 most of the newly evaporated molecules escape into the surrounding atmosphere and never come back |
front 29 what increases the rate of vaporization | back 29 increasing temp increasing surface area decreasing strength of intermolecular forces |
front 30 is motor oil volatile or nonvolatile | back 30 nonvolatile |
front 31 is vaporization endothermic or exothermic process | back 31 endothermic |
front 32 why do weak intermolecular forces result in volatile substances | back 32 because the intermolecular forces are easily overcome by thermal energy |
front 33 what happens if the pressure increases in a liquid-vapor system | back 33 some of the vapor condenses, bringing the pressure back down to the equilibrium pressure |
front 34 what is sublimation | back 34 the transition from solid to gas |
front 35 what is deposition | back 35 the transition from gas to solid |
front 36 why does sublimation occur at a greater rate than deposition | back 36 because of the most newly sublimed molecules escape into the surrounding atmosphere and never come back |
front 37 is melting ice endothermic or exothermic | back 37 endothermic because it absorbs heat from the liquid |
front 38 is freezing endothermic or exothermic | back 38 exothermic because heat is released |
front 39 what takes less time: heat of vaporization or heat of fusion | back 39 heat of fusion |
front 40 what is the triple point in a phase diagram | back 40 represents the unique set of conditions at which three states are equally stable and in equilibrium |
front 41 what is unique about water | back 41 the solid form is less dense than its liquid form, which is why ice floats water expands when it freezes |