2
CHEM 1301A midterm Exam with accurate detailed || || || || || || ||
solutions
Atoms - ✔✔Building blocks of matter
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- Protons: + charge, found in nucleus
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- Electrons: - charge, outside nucleus, very light
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- Neutrons: no charge, found in nucleus
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Atomic Number - ✔✔The number of protons in the nucleus of an atom
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Mass Number - ✔✔The sum of the number of neutrons and protons in an atomic nucleus
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Isotopes - ✔✔Atoms with the same number of protons but a different number of neutrons
|| || || || || || || || || || || || || ||
- Have same atomic number but different mass
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Isotopic Abundance - ✔✔Average atomic mass =
|| || || || || || ||
(% isotopic abundance/100) x isotopic mass
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Ions - ✔✔Positively and negatively charged atoms
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- Cation: loses an electron, becomes more +
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- Anion: gains an electron, becomes more -
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Molecules - ✔✔Groups of two or more atoms held together by chemical bonds
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- Compound: molecule containing atoms of more than one element
|| || || || || || || || ||
- Diatomic: only 2 atoms (HOBrFINCl)
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- Polyatomic: more than 2 atoms (H2O)
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,2
Moles - ✔✔The number of atoms contained in exactly 12g of pure C-12
|| || || || || || || || || || || ||
-NA: 6.02x10^23 ||
- # mol x NA = # particles
|| || || || || || ||
Molar Mass - ✔✔The mass of one mole of molecules
|| || || || || || || || ||
- sum of atomic masses of all the atoms in a molecule
|| || || || || || || || || || ||
- n = m/MM
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Mass % - ✔✔mass % = (mass of one species / total mass of sample) x 100%
|| || || || || || || || || || || || || || || ||
- useful for: % of an element in a compound, % of a compound on a mixture
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Empirical and Molecular Formulas - ✔✔- Empirical: the simplest ratio of atoms in a molecule|| || || || || || || || || || || || || ||
- Molecular: whole ratio
|| || ||
- Steps to find molecular from empirical:
|| || || || || ||
1. m/MM to find moles
|| || || ||
2. divide by smallest n to get the ratio
|| || || || || || || ||
3. multiply to get to the nearest whole number
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Mole Fraction and % - ✔✔Mole fraction: # n of one species / total n
|| || || || || || || || || || || || || ||
Mole %: (# n of one species / total n) x 100%
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Average Molar Mass of Mixtures - ✔✔MM = (Xa x MMa) + (Xb x MMb) + (Xc x MMc) etc.
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- X is the mole fraction
|| || || || ||
Molarity - ✔✔The number of moles of solute per liter of solution || || || || || || || || || || ||
- M = amount of solute (n) / amount of solution (n)
|| || || || || || || || || || ||
- M = n/V
|| || ||
, 2
- molarity may change if temp. changes because temp. affects volume
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Dilution - ✔✔Reducing the concentration of a solution || || || || || || ||
- number of moles of solute does not change, given that no chemical reaction takes place
|| || || || || || || || || || || || || || ||
- M1V1 = M2V2
|| || ||
Density of a Solution - ✔✔d = mass of solution / volume of solution
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- always refers to entire solution
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ppm and ppb - ✔✔ratio of the mass of solute to the mass of solution (same units) and multiplied
|| || || || || || || || || || || || || || || || || || ||
by 1 million/billion
|| ||
- ppm/b = (mass solute / mass soltution) x 10^6 or 9
|| || || || || || || || || || ||
- ppm: mass solute is very small compared to very small relative to mass of solution
|| || || || || || || || || || || || || || ||
- ppm: very low concentrations of solute
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Law of Conservation of Mass - ✔✔The combined mass of the reactants equals the combined
|| || || || || || || || || || || || || || ||
mass of the products || || ||
% Yield - ✔✔% yield = (actual yield/theoretical yield) x 100
|| || || || || || || || || ||
- theoretical yield gives the amount of product that would be produced if the reaction went
|| || || || || || || || || || || || || || || ||
perfectly
Limiting Reagent - ✔✔Reagent whose amount is insufficient to react completely with all other
|| || || || || || || || || || || || || ||
reagents ||
- once the limiting reagent is consumed, the reaction stops
|| || || || || || || || ||
1. Balanced equation
|| ||
2. Calculate moles
|| ||
3. Divide moles by corresponding stoichiometric coefficient
|| || || || || ||
CHEM 1301A midterm Exam with accurate detailed || || || || || || ||
solutions
Atoms - ✔✔Building blocks of matter
|| || || || ||
- Protons: + charge, found in nucleus
|| || || || || || ||
- Electrons: - charge, outside nucleus, very light
|| || || || || || ||
- Neutrons: no charge, found in nucleus
|| || || || || ||
Atomic Number - ✔✔The number of protons in the nucleus of an atom
|| || || || || || || || || || || ||
Mass Number - ✔✔The sum of the number of neutrons and protons in an atomic nucleus
|| || || || || || || || || || || || || || ||
Isotopes - ✔✔Atoms with the same number of protons but a different number of neutrons
|| || || || || || || || || || || || || ||
- Have same atomic number but different mass
|| || || || || || ||
Isotopic Abundance - ✔✔Average atomic mass =
|| || || || || || ||
(% isotopic abundance/100) x isotopic mass
|| || || || ||
Ions - ✔✔Positively and negatively charged atoms
|| || || || || ||
- Cation: loses an electron, becomes more +
|| || || || || || ||
- Anion: gains an electron, becomes more -
|| || || || || || ||
Molecules - ✔✔Groups of two or more atoms held together by chemical bonds
|| || || || || || || || || || || ||
- Compound: molecule containing atoms of more than one element
|| || || || || || || || ||
- Diatomic: only 2 atoms (HOBrFINCl)
|| || || || ||
- Polyatomic: more than 2 atoms (H2O)
|| || || || || ||
,2
Moles - ✔✔The number of atoms contained in exactly 12g of pure C-12
|| || || || || || || || || || || ||
-NA: 6.02x10^23 ||
- # mol x NA = # particles
|| || || || || || ||
Molar Mass - ✔✔The mass of one mole of molecules
|| || || || || || || || ||
- sum of atomic masses of all the atoms in a molecule
|| || || || || || || || || || ||
- n = m/MM
|| || ||
Mass % - ✔✔mass % = (mass of one species / total mass of sample) x 100%
|| || || || || || || || || || || || || || || ||
- useful for: % of an element in a compound, % of a compound on a mixture
|| || || || || || || || || || || || || || || ||
Empirical and Molecular Formulas - ✔✔- Empirical: the simplest ratio of atoms in a molecule|| || || || || || || || || || || || || ||
- Molecular: whole ratio
|| || ||
- Steps to find molecular from empirical:
|| || || || || ||
1. m/MM to find moles
|| || || ||
2. divide by smallest n to get the ratio
|| || || || || || || ||
3. multiply to get to the nearest whole number
|| || || || || || || ||
Mole Fraction and % - ✔✔Mole fraction: # n of one species / total n
|| || || || || || || || || || || || || ||
Mole %: (# n of one species / total n) x 100%
|| || || || || || || || || || ||
Average Molar Mass of Mixtures - ✔✔MM = (Xa x MMa) + (Xb x MMb) + (Xc x MMc) etc.
|| || || || || || || || || || || || || || || || || || ||
- X is the mole fraction
|| || || || ||
Molarity - ✔✔The number of moles of solute per liter of solution || || || || || || || || || || ||
- M = amount of solute (n) / amount of solution (n)
|| || || || || || || || || || ||
- M = n/V
|| || ||
, 2
- molarity may change if temp. changes because temp. affects volume
|| || || || || || || || || ||
Dilution - ✔✔Reducing the concentration of a solution || || || || || || ||
- number of moles of solute does not change, given that no chemical reaction takes place
|| || || || || || || || || || || || || || ||
- M1V1 = M2V2
|| || ||
Density of a Solution - ✔✔d = mass of solution / volume of solution
|| || || || || || || || || || || || ||
- always refers to entire solution
|| || || || ||
ppm and ppb - ✔✔ratio of the mass of solute to the mass of solution (same units) and multiplied
|| || || || || || || || || || || || || || || || || || ||
by 1 million/billion
|| ||
- ppm/b = (mass solute / mass soltution) x 10^6 or 9
|| || || || || || || || || || ||
- ppm: mass solute is very small compared to very small relative to mass of solution
|| || || || || || || || || || || || || || ||
- ppm: very low concentrations of solute
|| || || || || ||
Law of Conservation of Mass - ✔✔The combined mass of the reactants equals the combined
|| || || || || || || || || || || || || || ||
mass of the products || || ||
% Yield - ✔✔% yield = (actual yield/theoretical yield) x 100
|| || || || || || || || || ||
- theoretical yield gives the amount of product that would be produced if the reaction went
|| || || || || || || || || || || || || || || ||
perfectly
Limiting Reagent - ✔✔Reagent whose amount is insufficient to react completely with all other
|| || || || || || || || || || || || || ||
reagents ||
- once the limiting reagent is consumed, the reaction stops
|| || || || || || || || ||
1. Balanced equation
|| ||
2. Calculate moles
|| ||
3. Divide moles by corresponding stoichiometric coefficient
|| || || || || ||
