ch6-chemical analysis

Question 1

whatre mixtures

Answer 1

2 or more elements that ARENT chemically combined

Question 2

whatre the 4 physical ways of seperating mixtures

Answer 2

1-filtration
2-crystalisation
3-distilation
4-chromotography

Question 3

whatre the 2 types of distilation

Answer 3

fractional and simple

Question 4

whatre the differences between fractional and simple distilation

Answer 4

they both use a condenser (surrounded by cool water) but simple is used to seperate solid from liquid while fractional is used to seperate 2 liquids with different boiling points

Question 5

when is filtration used

Answer 5

to seperate insoluble solids from a liquid

Question 6

when is crystalisation used

Answer 6

to seperate a soluble solid from a liquid by heating the liquid which evaportaes away from the solid thats colleted at the beaker

Question 7

why is paper chromotography used

Answer 7

to identify pure substances from mixtures and analyse unkknown substances in solutions

Question 8

descrube the method of paper chromotography

Answer 8

1- draw a starting line in pencil (cause it wont dissolve) on the bottom of the paper
2-place 2 dots woth different colors
3-place paper in solvent
4-pure substances will produce 1 dot while mixtures will produce more than 1
5-calculate rf value

Question 9

what happens in paper chromotography if a substance is more soluble

Answer 9

itll move farther up the paper and be in mobile phase for longer

Question 10

what is in stationary phase and whats in mobile phase

Answer 10

mobile- solvent since its continuesly moving
stationary-paper since it doesnt move

Question 11

how do we calculate rf values from chromorography

Answer 11

distance traveled by substance/distance traveled by solvent

Question 12

why do we use rf values

Answer 12

to identify different substances thatre matched against databases

Question 13

what are the characteristics of ammonia

Answer 13

sharp chocking smell

Question 13

whats the positive test for ammonia

Answer 13

damp red litimus paper turns blue and white smoke of ammonium chloride when near hydrogen chloride gas (from hcl)

Question 13

whats type of white smoke is released when ammonia is held near hyrodgen chlorine gas (from hcl)

Answer 13

ammonium chlride smoke

Question 14

whats the test for hydrogen

Answer 14

lighted splint pops

Question 15

whats the test for oxygen

Answer 15

glowing splint relights

Question 16

whats the test fir chlorine

Answer 16

damp red litimus paper turns blue then white

Question 17

whats the test for carbon dixode

Answer 17

lime water(calcium hydroxide)turns cloudy

Question 18

what 3 metals form white precipitates when reacted with sodium hydroxide

Answer 18

calcium aluminium and magnesium

Question 18

whatre the 2 ways to test for metal positive ions

Answer 18

flame tests and sodium hydroxide precipitate test

Question 18

what colour precipitate is formed when iron (3) ions react with sodium hydroxide

Answer 18

brown

Question 19

what colour precipitate is formed when copper ions react with sodium hydroxide

Answer 19

blue

Question 19

what colour precipitate is formed when iron (2) ions react with sodium hydroxide

Answer 19

green

Question 20

what metal white precipitate dissolves in sodium hydroxide

Answer 20

aluminium

Question 21

what 5 metal ions can be tested using flames

Answer 21

lithium sodium potassium calcium barium

Question 22

what flame colour is a positive lithium ion

Answer 22

crimson

Question 23

what flame colour is a positive sodium ion

Answer 23

yellow

Question 24

what flame colour is a positive potassium ion

Answer 24

lilac

Question 25

what flame colour is a positive calcium ion

Answer 25

red

Question 26

what flame colour is a positive barium ion

Answer 26

green

Question 27

how do we test for carbonates

Answer 27

1- add dilue acid 2-acid will react w carbonate to produce co2 and it will fizz 3-carbon dioxide gas should turn limewater cloudy

Question 27

what are the 3 halide ions we can test for

Answer 27

bromide chloride and iodide

Question 28

how do we idenitfy halide ions

Answer 28

first add nitric acid then silver nitrate solution then diff halide will form diff coloured precipitates

Question 29

whats color is the silver nitrate precipitate of chloride

Answer 29

white

Question 30

whats color is the silver nitrate precipitate of bromide

Answer 30

cream

Question 31

whats color is the silver nitrate precipitate of iodide

Answer 31

yellow

Question 32

what 2 substances do you add to identify sulfates

Answer 32

add hydrochloric acid then barium chloride

Question 33

what precipitate di sulfates form

Answer 33

white barium sulfate precipitate