6180625
Description
Flashcards by Minoshka Bocarro, updated more than 1 year ago
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Created by Minoshka Bocarro
over 7 years ago
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| Question | Answer |
| Stoichiometry | The study of relative amounts, ratios, of substances involved in chemical reactions |
| A balanced chemical equation indicates | Mole ratio of reactants and products (the relative number of molecules participating in a chemical reaction) |
| A balanced chemical equation does not indicate | The rate of a reaction The extent of a reaction Requires or gives off heat What temperature or pressure is needed How individual atoms or molecules are transformed from reactants to products |
| Mass-mass stoichiometry | Calculating the mass of one substance in a reaction by using the equation and mass of one of the other substances -write balanced equation (known and unknown) -change known mass into moles -molar ratio used to predict moles -change the moles into mass |
| Limiting reactant | The reactant completely used up Determines the amount of product formed |
| Excess reactant | Any unreacted reactents |
| Mass-concentration stoichiometry | Two solutions may be mixed to form a precipitate or solids may dissolve in some solutions to form new products Same steps as mass-mass but using the formula n=cV |
| Gravimetric analysis | Quantitative analysis by mass |
| Weighing to constant mass | A repetitive cycle of heating and weighing the sample until no further decrease in mass is detected |
| Alkalinity | A measure of how well a body of water is able to resist changes in pH and therefore withstand acid pollution |
| Buffers | Some solutes in water can act to resist changes in pH0 |
| Volumeteric analysis | Measured volumes of solutions where one is an accurately known concentration and the unknown concentration of the second solution can be determined using stoichiometry |
| Solution stoichiometry | Involves reactions in solution such as precipitation reactions and the neutralization of an acid and a base |
| Acid-base titrations | Experimental technique used for volumetric analysis based on neutralisation reactions where the unknown concentration of a solution is determined by reacting it with a solution of known concentration |
| Standard solution | A solution of known concentratiotn Prepared by dissolving an accurate amount of solute in water using a volumetric flask calibrated to contain the specific volume |
| Burette | Instrument used to deliver definite but variable volumes of liquid |
| Titre | The volume of liquid measured by the burette |
| Aliquot | A known volume of liquid delivered by a pipette |
| Equivalence point | Point at which chemically equivalent amounts of acid and base are present (according to equation) |
| End point | Point at which the indicator changes colour usually about one drop after equivalence point but only if carefully chosen to make sure that it is close to the equivalence point |
| Concordant | Titres within 0.05 mL of each other |
| Primary standard | Pure substances that: -have a high state of purity -accurately known formula -stable (not change over time during storage or a reaction with the atmosphere) -cheap & readily available - high molar mass so that weighing errors are minimised |
| Indicators | Substances that have different colours depending on the pH of their surroundings |
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