unit 5) stochiometry

Question 1

what is a quantitive reaction

Answer 1

its a reaction where 99% or more complete
one reaction is completly used up (reaction wont stop till no more reactant)

Question 2

whats a spontenious reaction

Answer 2

its a rection that occurs as soon as reactants are mixed

Question 3

whats one thing that must happen to make a chemical reaction

Answer 3

there must be collisions collison reacttion theory- (chem entites must collide to cause a reaction)

Question 4

what are the steps of net ionic equations

Answer 4

1- balanced chem equation
2- then they dissociate is soluble ionic compounds
3- then remove any spectator ions any that are the same on both sides
4- re-write

Question 5

when do the ions in the dissociation process have coeffs

Answer 5

when the compound has a coeff in front or if theres a charge that was swapped onto it

Question 6

when hydro carbon combustion and odd number on one side and even on other what do you do

Answer 6

add up coeffs that are already there then write number on the oxygen and double on the product side

Question 7

what are the steps to gravimetric stoichiometry

Answer 7

1- write balanced chem equation / write info
2- then find moles of compound / element with the most info
3- then times required over given to find moles for thing tring to find
4- then solve for mass or whatever it is trying to find

Question 8

what is the limiting regent

Answer 8

reactant whoes entite completly consumed in a reaction none is left over

Question 9

what is execess regent

Answer 9

reactant entities present large amounts so some left over

Question 10

whats a common way when testing stochiometry

Answer 10

filtering

Question 11

what is the predictied value in percent yield and percent differnece

Answer 11

the predictied value is the stoichemestry

Question 12

what is the experimental values in percent yield and percent differece

Answer 12

theyre info from the lab

Question 13

when looking for the experimental value in percent yield what fomula do you use

Answer 13

exp yield= predicted times by % / 100

Question 14

what are some reasons that experiments can be inaccurate

Answer 14

• mesuments could be rounded
• purity not always 100% pure
• washing percipitate) fine particles may be lost during filtration
  -quolitative judgemnts- may think reaction do when isnt

Question 15

when given an experiment and says mass of paper and mass of paper and reactant what would you first to

Answer 15

sub values of filter paper and compound and filterpaper combined then its just experimental and then thats the experimental value

Question 16

with gas stoichemestry how do you solve

Answer 16

1- balanced chem reaction
2- then find number of moles if stp of satp then use n=v/vm if not use pv=nrt
3- after finding moles use reqiured/given to find moles of substance looking
4- solve for whatever value needed usally m

Question 17

whats the difference between qualitative analysis and quantitative analysis

Answer 17

qualitative- identifying a substance present
qualntitative - identifying mass / quantitiy there

Question 18

in colorimetry solution color what groups dont impact color

Answer 18

groups, 1, 2 and then 17

Question 19

how do you identify what element goes with what color

Answer 19

specific elements on the table thats in the compound is the color

(look for one element on there the ion thats on the color table makes the whole compound color )

Question 20

what is spectrophotometry

Answer 20

aq ions can be identified by eye but more precise when light produces rainbow then has sip to only show one color then detects how much absorbed

Question 21

whats another way to identify elements with colors

Answer 21

flame colors ) several metal ions turn flames different colors

Question 22

whats law conservation mass

Answer 22

matter cannot be made nor destroyed but the reactants just re-arrange into new products

Question 23

whith quantitive analysis involving percipitation what is it combined with

Answer 23

its combined with excess quantity of another reactant to make sure all sample reacts

Question 24

in gravimetric analysis with precipitation reaction what is it not possible to predict quantity

Answer 24

the quantity of excess reagent

Question 25

what experiment can you use to determing limiting reagent completeted

Answer 25

the trial and error procedure the top of the solution
creates a clear layer on top shows limiting reagent complete

Question 26

how to determine a reaction is quantitive

Answer 26

1- balanced chem equation
2- mols then req/given to get other mols
3- then find mass of it
4- then mass of filter paper - filter paper wirh added precipitate
5- percent diff then percent yield

Question 27

the diff between theo yield and actual yield can have multiple causes

Answer 27

• some reactants are unreacted
  -some product may be lost when transfering containers
  -some reactants can form other products

Question 28

what is the rule of thumb

Answer 28

the quantity / amount excess reagent is 10% more then required / limiting
(or just times by 1.1)

Question 29

how to know when to use rule of thumb

Answer 29

when question says something is excess reagent and asking to solve mass g of it then use stoich then to get excess times answer by 1.1

Question 30

how do you determine which thing is excess and limiting

Answer 30

1) convert both into mols

2) use the mols of the compound furthest on left times req/given to find moles of other thing already predicted moles

3) then see if req/given value is bigger / smaller then original mols

• if req/given value bigger then n=m/M then its limiting vise vera

Question 31

what does titration calculate

Answer 31

it helps solve the amount concentration of substance in the solution

Question 32

were is the titrant located in lab

Answer 32

the titrant is in the buret and is added into the erlenmeyere flask (sample value)

Question 33

what does the burret do

Answer 33

it has a precisely mared glass cylinder allows precise accurate measurment and controls how much volume of reacting solution

Question 34

what does the elenmeyer flask do

Answer 34

it holds the sample solution

Question 35

what does the pipette do

Answer 35

it transports measured vol of sample solution in flask

Question 36

what is the equivalence point

Answer 36

when exact theroretical amount tirtant has been added to completely react with sample

( two substances fully reacted just enough so none leftover)

Question 37

during acid / base titration whats equivelence point

Answer 37

it all depends and isnt always 7 because of strong acids/ weak and strong bases / weak

Question 38

how do you measure equivence point

Answer 38

• by looking at the sudden change in ph color and staying perminetly that color
• or how well in conducts

Question 39

what does endpoint stand for

Answer 39

it is when ou actually see a sudden change moment you know when youre reaction is finished (like color in ph)

Question 40

what is the solution is the buret called / in flask

Answer 40

the titrent in buret is B
the sample in erlemeyer flask is A

Question 41

how do you solve titration problems

Answer 41

-pick the vol of solution added within 0.2 range and average them
-then write under the same compund/entites as vol
- then use stoich to solve for the c of it