Practical 3 - Determination of chloride salts

Question 1

Why are flame tests done using the air vent and not by putting the nichrome loop in the flame?

Answer 1

An immediate but brief colour is imparted to the entire flame to give a more vivid colour.

Question 2

Why shouldn’t you pour liquid straight into the vent?

Answer 2

Not all of it will be vapourised and drops will fly up the Bunsen.

Question 3

What is hard to notice in the flame?

Answer 3

The white colour of Beryllium.

Question 4

How is nichrome wire cleaned?

Answer 4

In 1M HCl and then flamed.

The hottest part of a blue Bunsen burner flame is the tip of the inner blue cone (also known as the primary combustion zone).

Question 5

Give the calculations for finding the moles and finding the concentration of a substance.

Answer 5

n = m/M

c = n/V

Question 6

How do you convert mol/L to mol/ml?

Answer 6

Divide by 1000.

Question 7

AgNO3 + XCl →

Answer 7

AgCl + XNO3

Question 8

2AgNO3 + XCl2 →

Answer 8

2AgCl + X(NO3)2

Question 9

What are the formulas of:

Magnesium chloride
Strontium chloride
Calcium chloride

Answer 9

MgCl2.6H2O
SrCl2.6H2O
CaCl2.2H2O

Question 10

Why is silver nitrate stored in a brown bottle?

Answer 10

Silver nitrate is stored in a brown bottle because it is sensitive to light. When exposed to light, silver nitrate can undergo a decomposition reaction:
2AgNO3 →2 Ag + 2NO2 + O2