| Question | Answer |
| Actual Yield vs. Percent Yield | Actual yield / theoretical yield x 100% = percent yield |
| Theoretical yield | Amount of a product formed when the limiting reagent is completely consumed. Maximum amount of compound that can be produced |
| Limiting reactant (limiting reagent) | The reactant that runs out first and thus limits the amounts of products that can form. To find, compare mole ratio of balanced equations with mole ratio of reactants actually present |
| Stoichiometric Mixture | One that contains the relative amounts of reactants that match the numbers in the balanced equation. All reactant consumed to form products |
| Chemical reaction | Chemical change involves a reorganization of the atoms in one or more substances. Bonds have been broken and new ones have been formed. Atoms neither created nor destroyed. Gives 2 types of information. 1) Nature of reactants and products. 2) Relative numbers of each |
| Molecular formula | Exact formula of the molecule involved. Must know molar mass |
| Empirical formula | Smallest whole-number ratio |
| Determining the formula of a compound | To find formula, use weighed sample of compound and decompose it into its elements or react it with oxygen to produce other substances |
| Percent composition of compounds | 2 ways of describing composition of a compound. 1. Numbers of constituent atoms. 2. Percentages (by mass) of its elements |
| Formula Unit | Molecular formula equivalent, for ionic compounds |
| Molar mass | The mass in grams of one mole of the compound |
| Avogadro's Number | 6.022 x 10^23 atoms = 1 mole |
| Mole | The number equal to the number of carbon atoms in exactly 12 grams of pure C-12. Used for counting atoms. The mole is defined such that a sample of a natural element with a mass equal to the element's atomic mass expressed in grams contains 1 mole of atoms |
| Average Atomic Mass | Atomic weight given on the periodic table an average value of all the isotopes of given element. Percentages based on commonality in nature |
| Mass Spectrometer | Most accuarate meathod for comparing masses of atoms. Atoms or molecules passes into beam of electrons which knock off other e- and hcange them into positive ions. Ions go into magnetic field and are deflected based on their own magnetic field. Most massive ions deflected the smallest amount. Comparison of positions gives accurate values of relative masses |
| Modern system for atomic masses based on C-12 | C-12 = exactly 12 atomic mass units (amu) |
| Counting by Weighing | Count atoms as if they were all identical. Simply need to know the average mass of the objects. Can determine the number of atoms in a given sample by finding its mass. |
| Chemical Stoichiometry | Quantities of materials consumed and produced in chemical reactions |
18 cards - created sep 20, 6:04pm