chemical tests

Question 1

what precipitate do iodide ions form

Answer 1

yellow

Question 2

what colour do sodium ions go in flame tests

Answer 2

yellow

Question 3

test for hydrogen

Answer 3

use a lit splint - gives a squeaky pop

Question 4

test for oxygen

Answer 4

use a glowing splint - it will re-light it

Question 5

test for carbon dioxide

Answer 5

limewater goes cloudy

Question 6

test for chlorine

Answer 6

it turns moist litmus paper white

Question 7

test for ammonia

Answer 7

turns damp red litmus paper blue

Question 8

test for water using anhydrous copper sulfate

Answer 8

add it to sample - if water is present it will go from white to blue

Question 9

physical test to see if water is pure

Answer 9

it will boil at 100 degrees

Question 10

how to do flame test

Answer 10

• dip nichrome wire in hydrochloric acide to remove any impurities
• dip in substance
• put at cone of roaring blue flame
• observe colour

Question 11

colours formed in flame test for positive ions for lithium

Answer 11

red

Question 12

colours formed in flame test for positive ions for sodium

Answer 12

yellow

Question 13

colours formed in flame test for positive ions for potassium

Answer 13

lilac

Question 14

colours formed in flame test for positive ions for calcium

Answer 14

orange red

Question 15

colours formed in flame test for positive ions for copper

Answer 15

blue green

Question 16

for ammonium using sodium hydroxide solution

Answer 16

ammonia gas will form NH3

turns damp red litmus paper blue

Question 17

tests for copper(ii), iron(ii) and iron (iii) using sodium hydroxide solution

Answer 17

copper(ii) - blue precipitate of copper hydroxide
iron(ii) - green precipitate of iron hydroxide
iron (iii), brown precipitate of iron hydroxide