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45 Cards in this Set
- Front
- Back
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Lab safety procedures (5) |
-natural fibres -never touch or taste chemicals - bring hand near test tube to test for heat - clamp test tubes near the top at a 45degree angle pointing away from people - use appropriate lubricant when inserting glass tubing/thermometer into rubber stoppers |
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caution shape vs dangerous shape |
triangle for caution, octagon for dangerous |
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Scientific method |
observe, hypothesis, design experiment, repeat, eventually make theory or law. |
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law |
statement of fact without explanations |
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theory |
a generally accepted set of explanations |
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manual seperation |
use hand or magnet |
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decanting |
pouring a liquid off of a solid sometimes using a rod |
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filtering |
-takes advantage of varying particle size can only be used if a solid is mixed, NOT dissolved in a liquid. -a vacuum can speed up the process |
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evaporation |
-recovers solids dissolved in liquids -takes advantage of boiling point -calculate mass before and after evaporation to determine concentration -use when liquid is not important |
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Distillation |
-evaporation except vaporized liquid is caught and condensed to separate the solute and the solvent -takes advantage of boiling point - fractional distillation is used for substances with close boiling points. |
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Solvent Extraction |
-takes advantage of solubility - add water to dissolve one component of mixture and filter it to separate the dissolved substance from the undissolved substance -can be used for liquids because the solution that is soluble will have a greater density when the solution is added to it so it will sink to the bottom |
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Recrystallization |
-takes advantage of concentration -put impure solid in evaporating dish and add water to dissolve the solid. slowly heat up the dish and the first solid/crystal that forms will be the element that is most abundant in the mixture. |
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centrifugation |
takes advantage of different masses of particles - put substance in the centrifuge and it will spin and the heavier particles will sink to the bottom. -does not work for solutions or anything in which the particles would not sink to the bottom eventually without a centrifuge. |
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Chromatography |
takes advantage of solubility -has solvent carry solutes over stationary phase and they separate based off of solubility. |
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solute |
what has been dissolved |
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solvent |
what dissolves a substance. |
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characteristics of pure substances (5) |
-chemically combined -fixed proportions -fixed properties -one type of chemical unit(atom or molecule) - includes elements and compounds |
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characteristics of impure substances (5) |
-2 or more substances physically combined - unfixed proportions -random properties - can be heterogeneous or homogeneous |
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significant digits |
-all the digits you are certain of plus one estimate - do NOT apply to counted numbers or defined values. |
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multiplication and division with sig figs |
answer has same number of sig figs as the number with the fewest sig figs in the equation |
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adding and subtracting with sig figs |
answer is rounded to the decimal place of the number with the fewest |
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anions |
negative ions (non metals) |
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cations |
positive ions (metals) |
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compounds charge |
neutral |
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polyatomic ions |
charged group of covalently bonded ions |
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ionic compound |
electrons transferred. just because metals and nonmetals bond does not mean they are ionic |
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covalent compound |
electrons shared |
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covalent compound naming |
use prefixes |
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hydrates |
salts that have water incorporated into them. to signify one you put a dot and write H20 beside it |
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anhydrous |
hydrates with no water |
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naming acids |
ide- hydro...ic acid ate- ...ic acid ite- ...ous acid |
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avogadros hypothesis |
equal volumes of gases at the same temperature and pressure have the same number of particles. means that mole ratio=volume ration for gases |
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mole |
6.02 x 10^23 |
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standard molar volume of gases |
22.4L/mol |
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molar mass |
the mass of 1 mole of a substance when written 8u it means 8 times the mass of 1/12 of a carbon-12 atom. |
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Molarity |
moles per litre of solution |
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molar concentration notation |
signified by square brackets |
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standard solution |
a solution of known concentration |
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what happens when an ionic compound dissolves |
when an ionic compound dissolves the same ions that associated together to form the compound dissassociate |
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Empirical formula |
the simplest whole number ratio of of the atoms in a compound |
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molecular formula |
the actual ratio of the atoms in a compound |
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Evidence of a chemical change (4) |
-precipitate forms -colour change -bubbles -noticeable absorption or release of energy/heat |
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steps for writing chemical equations |
-start with elements that appear in only one place on both sides of the equation - balance elements that appear in multiple spots last right before balancing atoms in elemental form -balance polyatomic ions as a group when possible -let coefficients lead you through an equation |
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formula for acid |
an acid is an anion with enough hydrogen to balance it. the H comes first in the equation |
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Formula for a base |
a base is a cation with enough hydroxide to make it neutral. the OH comes last in the equation |
