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115 Cards in this Set
- Front
- Back
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What are moles?
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The SI base unit used to measure the amount of a substance whose # of atoms of C in exactly 12g of carbon-12.
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What is Avogadro's #?
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6.02 x 10^23. (# of molecules in a mole.)
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What is molar mass?
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Mass in grams of 1 mole of a substance.
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What is mole ratio?
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The conversion factor that relates the amounts in moles of any 2 substances involved in a chemical reaction.
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What is the excess reactant?
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The substance that is not used up completely in a reaction.
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What is the limiting reactant?
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The substance that controls the quantity of product that can form in a chemical reaction.
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What is percent yield?
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The ratio of the actual yield to the theoretical yield multiplied by 100.
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# moles = ?
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mass given
---------------- molar mass |
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number of moles of given
---------------------------------- = coefficient of given |
number of moles of unknown
-------------------------------------- coefficient of unknown |
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mass =
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# of moles x molar mass
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22.4 L of a gas =
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1 mole at STP.
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What is an exothermic process?
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One that releases heat.
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What is an endothermic process?
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One that absorbs heat.
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What is enthalpy?
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Change in heat at constant pressure.
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What is entropy?
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Measure of the disorder of a system.
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What is a calorimeter?
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A meeasuring instrument that determines quantities of heat.
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What does the 'Law of Conservation of Energy' state?
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The fundamental principle of physics that the total energy of an isolated system is constant despite internal changes.
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What is activation energy?
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The energy barrier that must be overcome during a collision of two potential reactants in order for a reaction to occur.
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How is the Heat of Reaction affected by a catalyst?
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It's not. Activation energy is the one that affects it.
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What can Hess's law be used for?
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To predict energy changes that are not easily measured.
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What does Hess's law state?
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The energy change in an overall chemical reaction is equal to the sum of the energy changes in the individual reactions comprising it.
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What is heat of fusion?
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The heat required to convert a solid into a liquid with no temperature change.
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What is heat of vaporization?
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The heat required to convert a substance from the liquid to the gas.
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What is boiling point?
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The temperature at which a liquid changes to a gas.
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What is freezing point?
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The temperature at which a liquid changes to a solid.
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What is condensation?
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Liquefaction of vapor.
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What is melting point?
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The temperature at which a solid changes to a liquid.
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What is deposition?
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The change of state from a gas directly to a solid.
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What is concentration?
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The amount of solute per unit volume or mass of solvent or of solution.
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What is triple point?
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A point in a phase diagram where the three states of matter are in equilibrium.
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What is critical temperature?
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The temperature above which a gas cannot be liquefied; the temperature above which a substance cannot exhibit distinct gas and liquid phases.
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What is equilibrium?
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A balanced condition resulting from two opposing reactions.
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What is a phase diagram?
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A graph of pressure versus temperature that shows the conditions under which the phases of a substance exist.
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What does the kinetic-molecular theory state?
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That particles of matter are always in motion.
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What is sublimation?
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The change of state from a solid directly to a gas.
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______ consist of large numbers of tiny, fast-moving particles that are far apart relative to their size.
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Gases
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The particles of a liquid are ____ and ____ ordered than those of a gas and are ____ ordered than those of a solid.
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closer, more, less
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Liquids have a _____ volume and a fairly ____ density, and they are relatively _________.
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definite, high, incompressible
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What property to liquids and gases have in common?
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They can both flow and are thus considered fluids.
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The particles of a _____ are not nearly as free to move about as those of a _____ or ____ are.
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solid, liquid, gas
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______ may be crystalline or amorphous.
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Solids
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What five assumptions are the kinetic-molecular theory of gases based on?
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1. Gases consist of large numbers of tiny particles that are far apart relative to their size.
2. Collisions between gas particles and between particles and container walls are elastic collisions. 3. Gas particles are in continuous, rapid, random motion. They therefore possess kinetic energy, which is energy of motion. 4. There are no forces of attractions between gas particles. 5. The temperature of a gas depends on the average kinetic energy of the particles of the gas. |
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KE = 1/2mv^2
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m = mass of particle
v = speed of particle |
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Use kinetic-molecular theory to explain expansion in gases.
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Gas particles move rapidly in all directions, without significant attraction between them.
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Use kinetic-molecular theory to explain fluidity in gases.
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Because the attractive forces between gas particles are insignificant, gar particles glide easily past one another.
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Use kinetic-molecular theory to explain low density in gases.
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The particles are so much father apart in the gaseous state.
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The kinetic-molecular theory is more likely to hold true for gases whose particles have what?
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Little attraction for each other.
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What is absolute zero?
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The temperature -273°C, given a value of zero in the Kelvin scale.
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One atmosphere of pressure (atm) is equal to ______ mm Hg.
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760.
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What is a barometer?
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A device used to measure atmospheric pressure. (Evangelista Torricelli)
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What does Dalton's law of partial pressures state?
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The total pressure of a gas mixture is the sum of the partial pressures of the component gases.
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What is the ideal gas law?
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The mathematical relationship among pressure, volume, temperature, and the number of moles of a gas.
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What is the ideal gas constant?
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The constant R. It's value depends on the units chosen for pressure, volume, and temperature.
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What is an ideal gas?
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A hypothetical gas that perfectly fits all the assumptions of the kinetic-molecular theory.
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What does STP stand for?
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Standard temperature pressure.
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Many gases behave nearly ideally if pressure is not very ____ and temperature is not very ____.
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high, low
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What does Boyle's law state?
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The pressure of a ideal gas is inversely proportional to its volume, if the temperature and amount of gas is held constant.
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What laws does the combined gas law contain?
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Charles's law, Boyle's law, and Gay-Lussac's law.
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What does Gay-Lussac's law state?
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When gases react, they do so in a definite proportion by volume, if the volumes are measured at the same pressure and temperature.
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What is a Pascal?
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The SI unit of pressure, equal to a force of one newton* per square meter.
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A gas whose pressure P, volume V, and temperature T are related by PV = nRT, where n is the number of moles of gas and R is the _______________.
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ideal gas law constant
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What does the ideal gas law state?
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The product of pressure and the volume of an ideal gas is directly proportional to the number of moles of the gas and the absolute temperature.
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What does Graham's Law of Diffusion state?
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That the rate of fefusion of gases at the same temperature and pressure are inversely proportional to the square roots of their molar masses.
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What are colloids?
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Mixtures formed by particles that are intermediate in size between those in solutions and suspensions. (Ex: milk)
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What is a suspension?
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A mixture in which the particles in the solvent are so large that they settle out unless the mixture is constantly stirred. (Ex: jar of muddy water)
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What is an electrolyte?
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A substance that dissolves in water to give a solution that conducts electric current.
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What is a solution?
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A homogeneous mixture of two or more substances in a single phase.
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The amount of solute that can be dissolved in a definite amount of solvent is used as the measure of _________.
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solubility
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Liquids that dissolve freely in one another in any proportion are __________.
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miscible
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Liquids that are not soluble in each other are _________.
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inmiscible
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What is molarity?
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The number of moles of solute in one liter of solution.
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molarity (M) = ?
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amount of solute (mol)
------------------------------ volume of solution (L) |
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What is molality?
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The concentration of a solution expressed in moles of solute per kilogram of solvent.
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molality = ?
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moles solute
--------------------------- mass of solvent (kg) |
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What are colligative properties?
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Physical properties of solutions that depend upon the number but not the kind of solute particles present.
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What is a nonelectrolyte?
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A substance whose aqueous solutions do not conduct electricity.
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What is an amalgam?
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An alloy that contains mercury.
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What is boiling point elevation?
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The increase in the boiling point of a solvent caused by the dissolution of a nonvolatile solute.
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What is precipitate?
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An insoluble substance that has been formed from substances dissolved in a solution.
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What are spectator ions?
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Ions in a solution that do not participate in a chemical reaction.
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What are alloys?
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Solid solutions in which the atoms of two or more metals are uniformly mixed.
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Increasing the surface area of the solute _________ the rate of dissolution.
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increases
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Agitation of a solute _________ the rate of dissolution.
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increases
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How does agitation of a solute increase the rate of dissolution?
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By dispersing the solute particles and bringing fresh solvent into contact with the solute surface.
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How does increasing the surface area of the solute increase the rate of dissolution?
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The more finely divided a substance is, the greater the surface area per unit mass and the more quickly it dissolves.
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Heating a solvent _________ the rate of dissolution.
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increases
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What is a saturated solution?
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A solution that contains the maximum amount of dissolved solute.
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What is an unsaturated solution?
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A solution that contains less solute than a saturated solution under the existing conditions.
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What is a supersaturated solution?
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A solution that contains more dissolved solute than a saturated solution contains under the same conditions.
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Increases in pressure ________ gas solubilities in liquids.
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increase
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Increasing the temperature usually _______ gas solubility.
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decreases
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Increasing the temperature generally __________ the solubility of solids.
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increases
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An equivalent temperature increase can result in a large _______ in solubility or some solvents and only a slight change for others.
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increase
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What is the symbol for the hydronium ion?
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H3O+.
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How is H3O+ formed?
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By the capture of a hydrogen ion by a water molecule. A strong covalent bond is formed between the hydrogen ion and water oxygen; all hydrogen ions in aqueous solution are bound inside hydronium ions.
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What is an amphoteric substance?
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A substance that can act as either an acid or a base in a reaction.
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What is a polyprotic acid?
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One with several hydrogens that can dissociate.
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What is a hydroxide ion's symbol?
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OH-.
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What is salt?
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NaCl. A solid compound composed of both metallic and nonmetallic elements.
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What is titration?
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A Procedure in which one solution is added to another solution until the chemical reaction between the two solutes is complete; the concentration of one solution is known and that of the other is unknown.
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What is end point?
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The point at which an indicator changes colour and a titration is stopped.
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What is an acid?
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A substance that produces H+(aq) ions in aqueous solution. Strong acids ionize completely or almost completely in dilute aqueous solution. Weak acids ionize only slightly.
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What is a base?
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A substance that produces OH- (aq) ions in aqueous solution. Strong soluable bases are soluble in water and are completely dissociated. Weak bases ionize only slightly.
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What is a neutralization reaction?
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A chemical change in which one compound acquires H+ from another. The compound that receives the hydrogen ion is the base; the compound that surrenders it is an acid.
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What is a strong acid?
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An acid that completely dissociates into hydrogen ions and anions in solution. Strong acids are strong electrolytes. (HCl)
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What is a strong base?
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A strong base is an base that completely dissociates into ions in solution. Strong bases are strong electrolytes. (Alkali metals)
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What is a weak acid?
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An acid that only partially dissociates into hydrogen ions and anions in solution. Weak acids are weak electrolytes.
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What is a weak base?
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A base* that only partially dissociates into ions in solution. Weak bases are weak electrolytes. (Ammonia)
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What is chemical equilibrium?
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A state of dynamic balance in which the rates of forward and reverse reactions are equal; there is no net change in concentrations of reactants or products while a system is at equilibrium.
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What is a conjugate acid-base pair?
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In Bronsted-Lowry terminology, a reactant and product that differ by a proton, H+.
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What is double replacement?
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A double displacement or metathesis is a reaction in which two reactants trade fragments:
AB + CD = AC + BD |
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What is an empirical formula?
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A formula that shows which elements are present in a compound, with their mole ratios indicated as subscripts.
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What is calorimetry?
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Experimental determination of heat absorbed or released by a chemical or physical change.
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Percent yield =
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actual yield (grams)
-------------------------------- theoretical yield (grams) |
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How does one find theoretical yield?
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* Balance the reaction and determine the stoichiometry or ratios of reactants to products.
* Find the number of moles of each starting material used. * Determine which reagent is limiting. * Calculate the moles of product expected if the yield were 100% based on the limiting reagent. * Calculate the grams of product corresponding to the number of moles expected. |
