unit 7 Flashcards

1
Q

mole ratios

A

allows us to convert between the moles of each reactant and products

determined from coefficients in the balanced equation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

limiting reactant

A

reactant that is totally consumed when a reaction is completed

limits amount of product that can be formed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

excess reactant

A

reactant that remains after the limiting reagent is consumed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

percent purity (by mass) =

A

(mass of pure substance / mass of impure sample) x 100%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

percent yield =

A

(amount of product obtained / amount of product expected) x 100%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

theoretical yield defnition

A

amount of product expected

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

percent composition definition

A

percent of a compound’s mass that comes from each element

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

how can a compounds theoretical percent composition be calculated?

A

its chemical formula

-calculate the mass contribution for each element
(moles of element / 1 mol of compound) x (Molar mass of element)

-add the masses to determine the mass of 1 mole of the compound

-divide the mass contribution for each element by the molar mass, multiply by 100%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

empirical formula definition

A

chemical formula that shows the simplest ratio of atoms of elements in a compound

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

molecular formula definition

A

actual number of each type of atom of a compound

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

structural formula defintion

A

shows the type, number, and arrangement of atoms in a formula, shows how atoms are bonded together

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

structural isomers definition

A

compounds with the same molecular formula but different structural formulas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

how to determine empirical formulas from percent composition

A
  1. put percents over 100g of the compound
  2. convert the mass of each element
  3. divide the numbers of moles for each element by smallest number of moles
  4. write formulas based on calculations
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

how to calculate the molecular formula of a compound

A
  1. calculate the empirical formula mass of the compound
  2. divide molecular formula mass by the empirical formula mass
  3. multiple subscripts by number calculated in step 2 to get formula
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

combustion analysis use

A

determine the empirical formula of a hydrocarbon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

combustion reaction products

A

water and carbon dioxide

17
Q

combustion analysis steps

A
  1. determine masses of C and H in original sample
  2. if a 3rd element is present, subtract measured masses of H and C from original sample mass
  3. determine moles of C and H (and 3rd element if present) in the original sample
  4. find the relative moles of each element by dividing the lowest number to give an empirical formula