Revision topic 6

Question 1

what are the 3 differences between compounds and mixtures

Answer 1

compounds have fixed compositions while mixtures dont, compounds need to be chemically separated, while mixtures more easily by filtration distillation crystallization and chromatography, compounds have their atoms have chemical bonds between them while mixtures dont have chemical bonds between there atoms

Question 2

what is filtration

Answer 2

it is a technique used to separate insoluble substances from substances that are soluble in a particular solvent

Question 3

what is cristilazation

Answer 3

It is the obtaining pure salt from a filtrate, by running a water bath for the filtrate and waiting till it hits its crystallization point by seeing crystals forming then put in a room temperature till it fully crystallizes

Question 4

what is distillation

Answer 4

It is the separation of two liquids in a mixture by boiling them then cool the vapor produced to condenses back to the liquid and this works because each liquid has different boiling points

Question 5

what are the possible problems of distillation

Answer 5

we cant get pure liquids because the vapor is given off before the boiling points

Question 6

what is chromatography

Answer 6

chromatography is a method used to separate and identify substances in a mixture

Question 7

explain how chromatography works

Answer 7

chromatography has a mobile phase and a stationary phase, where the mobile phase is the solvent and the stationary phase is the paper, each substance has a different attraction to the mobile phase and the stationary phase for example if a substance has more attraction to the stationary phase compared to the mobile phase it won’t travel very far

Question 8

how do we identify unknown substances found in chromatography

Answer 8

by dividing the distance moved by substance over the distance moved by a solvent to get a retention factor (Rf) which all substances have a set value for

Question 9

what is the test for hydrogen

Answer 9

a lighted splint pops

Question 10

what is the test for oxygen

Answer 10

a glowing splint relights

Question 11

what is the test for carbon dioxide

Answer 11

limewater turns cloudy white

Question 12

test for ammonia

Answer 12

red litmus paper turns blue

Question 13

test for chlorine

Answer 13

blue litmus paper turns red then bleach

Question 14

what is the flame color for Lithium, Sodium, Potassium, Calcium, and Barium

Answer 14

lithium - crimson 
sodium - yellow
potassium - lilac 
calcuim - red
barium - green

Question 15

how do you run flam test

Answer 15

nichrome loop dip it in HCl to sterilize it then put the metal of the loop then proceed to put it over a bunsen burner which burns blue then see the color change

Question 16

how do you test for positive ions using sodium hydroxide

Answer 16

add sodium hydroxide to a solution and if a white participate form then it either Al3+ or Mg2+ or Cl2+ if the solution gets dissolved with excuses sodium hydroxide then Al3+ is present but if not run a flame test to determine if it Cl2+ or Mg2+ (calcium burns red and magnesium burn is colorless) if a color participant forms then its either Cu2+ or Fe2+ or Fe3+ with copper forming blue, iron 2 forming green and iron 3 forming brown

Question 17

how do you test for carbonates

Answer 17

add dilute acid to a carbonate it would fiz and produce CO2, then the CO2 would react with limewater and turn cloudy

Question 18

how to test for Halide ions

Answer 18

add nitric acid to remove any carbonate ions, then add silver nitrate if a participant forms then a halide is present whit iodine being yellow, chloride being white, and bromide being creamy

Question 19

how to test for Sulfates

Answer 19

add hydrochloric acid to remove any carbonate then add barium chloride and if I white participate forms then a sulfate is present