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16 Cards in this Set
- Front
- Back
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Define a Molecule can an ionic compound be a molecule? |
combo of two+ atoms held by covalent bonds *ionic compounds do not form true molecules - defined by formula unit (empirical formula) b/c no molecule actually exists |
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Molecular Weight (amu)
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sum of atomic weights of all atoms in a molecule
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Formula Weight (amu)
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for ionic compounds, found by adding all atomic weights for contituents according to empirical formula (amu)
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What is a mole? what is avogadros number? define molar mass 1 mole of a compound is equal to its molecular weight - what is the mass of one mole of a compound called? |
Mole: quantity of any substance equal to the number of particles found in 12 grams of C-12 -number particles is called Avogadros number =6.02x10^22 mol^-1 ex: atoms, dollar bills, kittens... Molar mass: mass of 1 mole compound |
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Gram Equivalent Weight vs Equivalent Vs. Normality How does molarity ∆ from normality? |
not same as equivalent: number of moles of hydrogens H+ ions, or electrons, etc. a compound can donate ex: one mole HCl: donates one mol H+ 1 Equivalence Weight: amount of compound(in grams) that will donate a mole of something ex: HCl mm= 36.5g, so 36.5g to donate 1 mole H+ ex: H2CO3: mm= 62g/mol so only need 31g to produce 1 mole H+ Equivalents= mass compound (g) / gram equivalent weight (g) Normality (N): is simply equivalents/ L * most commonly used for [H+] ex: 1N solution acid has [H+]= 1 mole/liter Molarity Vs Normality Molarity= Normality/n * 1N HCl solution, the molarity would be 1M *in 1N of H2CO3, (H+=n=2),M= 0.5M note: one mole of HCl will not neutralize one mole of Ca(OH)2. they donate ∆ equivalents 1n vs 2n |
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Structural Formula
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shows bonds between atoms ex: C6H12O6 - glucose * no ID of they are arranged |
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Law of Constant Composition
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any pure sample of given compound will contain same elements in an identical mass ratio -ex: H2O samples- all have a ratio of 2:1 H to O in terms of mass 1 gram H for 8g of O |
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Empirical Formula vs Molecular Formula which one measures exact number which one measures the simplest ratio? |
Empirical: simplest whole number ratio of elements in compound **whole number ex: CH2O glucose CH2O -monosaccharides Molecular: exact number of atoms - multiple of empirical formula -ex: C6H12O6, glucose |
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Percent Composition
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Percent of element by mass in a compound %comp. = (mass elements / mm ) x100 * can use empirical formula or molecular- same ratio given %s of elements and the molar mass, can find the molecular formula - QUICK: multiply decimal version of % by the mm -divide by element's atomic weight to get ratio -simplify to get empirical formula(simplest ratio) |
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Types of reactions
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Combination Reaction - two reacants---> one product Decomposition Rxn -opposite combination usually w/ heat - one reactant breaks down into two products Combustion Rxn - involves fuel (usual hydrocarbon) - normal product CO2 and H2O -oxidation of a fuel Single Displacement Rxn - atom/ion replaced by another ion/element -often classified as redox rxn (∆ oxi. states) Double Displacement - metathesis rxn -swap places - usually part of product precipitates/ gas leaves and weak electrolyte remains Neutralization Reactions - double displacement rxn acid+base produce a salt and usually water |
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Tips for balancing chemical equations
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coefficients represent relative number of moles of given compound involved- in whole numbers -focus on least represented elements first -work way up to most represented normally oxygen and hydrogen |
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Limiting Reagent Vs Excess Reagent which is used up first? |
Limiting reagent is used up first in rnx, the rest left are the excess reagents * if values of multiple reacents given, most likely need to know the limiting reagent to find limiting reagent - compare the reactants in units of moles -gram-to-gram is misleading(need mm) for ratio -have to use stoichiometric ratios to see which one yields more(excess reagent) of the product |
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How do you calculate the percent Yield? How is the actual yield different than the theoretical yield? which type of yield accounts for the maximum amount of product generated |
Yield: amount product predicted(theoretically) or produced( actual yield) theoretical calculates max possible yield w/ balanced equation and limiting reagent Percent Yield= Actual / theoretical x100 |
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Which type of reaction classes generally take place in ionic solutions? What is a cation vs anion? what type of bonds do ions form? |
Ions: many redox and acid-base rxns occur in ionic solvents Cations : + charged Anions: Neg. charged both form ionic bonds: electrostatic attraction between oppositely charged particles multi chargeable ions Iron II --> Fe2+ Iron III --> Fe3+ Monatomic anions- end in -ide Hydride H- Sulfide S^2- Fluroide F- Oxide O^2- Nitride N^3- Phosphide P^3- Polyatomic anions w/ oxygens: oxyanions -ite (less oxygen ) and -ate( more oxygen) Nitrite NO2- Nitrate NO3- Sulfite SO3^2- Sulfate SO4^2- Hypo- even more less oxygen ex: Hypochlorite ClO- Per- most oxygen ex: perchlorate ClO4- |
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Ion charges are Ion charges the same as oxidation states? |
Ion charge= oxidation state Group 1/ alkali metals +1 Group 2/ alkali earth metals +2 Halogens(VIIA) (7 val e-) so -1 |
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Electrolytes
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Electrolyte: Solute that enables solutions to carry currents (electrical conductivity)ex: aqueous solutions - has ions- pure water is still weak- poor conductor only from autodissociation
**electrolytes are good if they are completely soluble or readily dissociate so nonpolar covalent compounds are super weak b/c hardly form current-carrying ions |
