Part 4 Flashcards

1
Q

how do you calculate number of moles present?

ex: how many moles are in 9.52g of MgCl2?

A

mol = weight of sample (g)/ mw

mol = 9.52 / 95.21 = .10 mol

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2
Q

to find moles given grams of a compound, what formula is used?

A

mol= g/mw

```
g= grams of sample
(mw= mw of compound)
~~~

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3
Q

what is the formula for percent composition of an element?

A

% composition = mass of X in formula / mw x 100

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4
Q

what is an ionic equation?

A

includes spectator ions that do not participate in the actual reaction (displacement rxn)

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5
Q

what is a net ionic reaction?

A

shows only the species involved in the reaction, not the spectators
(displacement rxn)

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6
Q

what type of reaction is double displacement and involves an acid reacting with a base to produce salt and water?

A

neutralization

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7
Q

how do you calculate theoretical yield?

A

theor. = (starting amount)(mw product) / ( mw of starting)

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8
Q

how do you calculate percent yield?

A

% yield= product amount/ theo. yield

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9
Q

the slowest step in a proposed rxn mechanism is known as what?

A

rate-determining step

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10
Q

how are orders of rxn determined?

A

experimentally

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11
Q

what is an enthalpy change?

A

represented by deltaH; the difference between the the potential energy of the products and the potential energy of the reactants

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12
Q

what does a negative delta H represent?

A

an exothermic reaction; heat is given off

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13
Q

what does a positive delta H represent?

A

an endothermic reaction; heat absorbed

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14
Q

as a rule of thumb, the rate of a reaction will double approximately, for each increase in temperature of how much?

A

10 degree Celsius increase= rate of rxn doubles approximately

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15
Q

what are the four main factors affecting reaction rate?

A
  1. reactant concentrations
  2. temperature
  3. medium
  4. catalysts
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16
Q

when the forward rate of rxn = the reverse, what is the rxn said to be at?

A

equilibrium

17
Q

what is Kc? what is it denotated as when dealing with gas?

A

equilibrium constant

kp= gas

18
Q

neutral, nonmetallic elements will always have electrons in what shell?

A

p

19
Q

how many electrons can a p-subshell hold?

A

6

20
Q

if a compound contains NH4 is it ionic or covalent bond?

A

ionic, even though it doesn’t contain a metal