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Question 1

What is the colour of arsenic?

Answer 1

Grey metal

Question 2

How does arsenic occur naturally?

Answer 2

As arsenic sulphide

Question 3

What is the structure of arsenic sulphide?

Answer 3

(S=)(S=)As-S-As(=S)(=S)
Two sulfurs double bonded to arsenic bonded with a single bond to sulfur bonded by a single bond to another arsenic double bonded to two sulfur atoms

Question 4

What is white arsenic?

Answer 4

Arsenic oxide

Question 5

What are the two structures of arsenic oxide?

Answer 5

1. (O=)(O=)As-O-As(=O)(=O)
   Similar to arsenic sulphide
2. O=As-O-As=O

Question 6

Which form of arsenic is poisonous?

Answer 6

Arsenic oxide

Question 7

How does arsenic bond within the body?

Answer 7

1. It bonds to the sulfur groups on enzyme proteins preventing them from working
2. It replaces the phosphate in DNA with arsenic

Question 8

How can arsenic be detected with hair?

Answer 8

Hair is a protein and bonds with keratine (which contains sulfur atoms).
Hair grows and so can be used to measure the levels of arsenic over time

Question 9

What was the old test used to detect for arsenic in the body?

Answer 9

Hydrogen Sulfide bubbled through a suspect solution and if a yellow precipitate of arsenic sulfide forms then arsenic is present

Question 10

What is the equation for the old test for arsenic?

Answer 10

H2S(g) + 2H3AsO4(aq) ==> As2S5(s) + 8H2O(l)

Question 11

Why were new tests for arsenic needed?

Answer 11

Because Arsenic Sulfide doesn’t last very long and so is not good evidence

Question 12

What is the marsh test?

Answer 12

This is a new test for arsenic.
Adding zinc and sulphuric acid to the sample suspected of containing arsenic will produce arsene gas (AsH3).
This is then passed along a heated glass tube which causes it to decompose into Arsenic metal.
This is a silvery/grey metal that is deposited and can be used as evidence

Question 13

What are the equations for the marsh test?

Answer 13

As2O3 + 6Zn + 6H2SO4 ==> 2AsH3 + 6ZnSO4 + 3H2O

2AsH3 + 1.5O2 ==> 3H2O + 2As

Question 14

What are the properties of arsenic gas?

Answer 14

It is extremely poisonous

Question 15

What are the benefits of the marsh test?

Answer 15

It could detect very small amounts of arsenic

Very specific because only arsenic behaves this way

Question 16

What is a destructive test?

Answer 16

This is where the sample is used up

Question 17

Is the marsh test a destructive test?

Answer 17

Yes

Question 18

What is the structure of arsene?

Answer 18

AsH3

Question 19

What do we use to detect the presence of arsenic today?

Answer 19

X-ray fluorescence spectroscopy

Question 20

What happens during x-ray fluorescence, What happens?

Answer 20

x-rays kicks out an inner electron (nearer the nucleus) which has more energy. Then one of the electrons higher up drops down to replace it

Question 21

What is scheele’s Green made from?

Answer 21

CuAsHO3

Question 22

What is the structure of copper arsenate?

Answer 22

Cu2+ As(-O)(-O)OH

The Arsenate forms a ligand around the copper

Question 23

What happened to the wall paper?

Answer 23

The wallpapers mould converted the wallpaper into arsene, dimethyl or trimethyl arsene

Question 24

What is the structure of trimethyl arsene?

Answer 24

As(CH3)3