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29 Cards in this Set
- Front
- Back
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composition of earth
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crust was broken by asteroid impacts, volcanic activity
volatile gases that were released reacted to change the composition of earth's atmosphere and surface |
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chemical equations
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proportions of reactants and products during a chemical reaction, changes on the atomic level, physical states
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types of reactions
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combination reaction
decomposition reaction single displacement reaction double displacement reaction combustion reaction |
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combination reaction
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2+ substances combine to form a product
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mole
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6.022*10^23 particles (avogadro's number)
relates mass of a substance to a number of particles it contains |
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molar mass
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mass (in g) equal to the mass of an individual atom or molecule (in amu)
mass of one mole of the substance (atom, molecule, formula unit) |
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stoichiometry
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quantitative relationship between the reactants and products involved in a chemical reaction
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law of conservation of mass
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the sum of masses of the reactants of a chemical equation is equal to the sum of the masses of the products
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balanced chemical equation
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mass and charge on both sides should be equal, balanced coefficients and elements
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combustion reactions
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reactions between oxygen (O2) and another element in a compound
ex. 4SO2 + 2O2 -> 4SO3 |
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hydrocarbons
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molecular compounds composed of only hydrogen and carbon
"organic" compounds products are CO2 and H2O |
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carbon cycle
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1) carbon enters the atmosphere as CO2
2) absorption by producers and photosynthesis 3) respiration 4) detritus, fossil fuels 5) combustion |
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photosynthesis
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plants use energy from sunlight to convert CO2 and H2O into glucose
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respiration
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living organisms use glucose as a source of energy
C6H12O6 + 6O2 -> CO2 + 6H2O |
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combustion of hydrocarbons
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same reaction as respiration
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percent composition
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=mass of A in the whole/mass of whole *100
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finding empirical formula
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1) convert percentages to grams (assume 100g)
2) convert grams to moles 3) write pseudoformula using moles as subscripts 4) divide all by smallest number of moles 5) multiply all mole ratios by number to make all whole numbers |
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empirical vs. molecular formulas
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many compounds have the same empirical formula but different molecular formulas
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mass spectrometers
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instruments to determine the mass of substances
-convert molecules into ions -separate ions based on mass/charge ratio |
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mass % composition
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empirical formula
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mass spectral data
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molecular mass
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find molecular formula
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1) find empirical formula weight
2) ratio of molecular weight to the empirical formula weight n= molecular weight/empirical formula weight 3) multiply each subscript of the empirical formula by n |
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combustion analysis
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common technique for analyzing compounds is to burn a known mass of compound and weight the amounts of product and by knowing the mass of the product and composition of constituent element in the product, the original amount of constituent element can be determined
once the masses of all constituent elements in the original compound have been determined the empirical formula can be found |
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combustion analysis part 2
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percent of carbon and hydrogen in CaHb can be determined from the mass of H2O and CO2 produced by combustion:
CaHb + excess O2 -> aCO2 (g) + b/2 H2O |
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limiting reactants
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substance that is completely consumed in the chemical reaction
determines the amount of product that can be formed during the reaction |
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how to find the limiting reactant
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1) convert first element to moles to moles of resulting compound
2) molar mass of compound 3) grams expected to produce do for both elements** but do it towards whatever you want to produce.. whichever gets less is the limiting reactant |
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theoretical yield
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calculated amount of product formed based on the amount of limiting reactant
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actual yield
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measured amount of product formed
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percent yield
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actual yield/theoretical yield * 100
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