topic 8:chemical analysis

Question 1

What is a pure substance?

Answer 1

Pure substance is a single element or compound not mixed with any other substance

Question 2

What is a formulation and how is it made?

Answer 2

A formulation is a mixture of compounds in measured quantities that has been designed as a useful product

Formulations include fuels, cleaning agents, paints, medicines, alloys, fertilisers and foods

Allies are mixtures of metals; they are harder than pure metals, so they have a particular purpose

Question 3

describe paper chromatography

Answer 3

1. A start line is drawn near the bottom of the paper. The mixture is spotted on the line.
2. A beaker is filled with a small amount of solvent.
3. Paper is hung on a rod and placed in a beaker.
4. Solvent travels up the paper, this separates the components.
5. Before solvent level reaches the end, the paper is taken out and the finish line is marked. The paper is dried.
6. The procedure works with different compounds have different affinity for the solvent/paper. Stronger attractions for the paper means it travels slowly with the solvent.
7. Paper is called the stationary phrase it doesn’t move. Solvent is the Mobile phase.

Question 4

How is RF calculated?

Answer 4

Distant move by the spot/distant move by the solvent

Question 5

Describe the test for hydrogen, oxygen, carbon dioxide and chlorine

Answer 5

hydrogen – pop with burning splint over gas
Oxygen – a glowing splint relights
Carbon dioxide – turns lime water milky
Chlorine – bleach is damp lit paper and makes it white

Question 6

describe the flame test results

Answer 6

Lithium – crimson red
Sodium – yellow flame
Potassium – Lilac
Calcium – orange
Copper – green

Question 7

describe the test for carbonate anions

Answer 7

add a dilute acid
Fizzing observed as CO2 is released

Question 8

describe sulphate test

Answer 8

Add a solution containing BA Cashions
White participate forms

Question 9

describe silver nitrate tests

Answer 9

Add a solution of a GN03
Chloride – white precipitate
Bromide – cream precipitate
Iodine yellow precipitate

Question 10

what are instrumental methods?

Answer 10

They are accurate, and sensitive and rapid methods which are useful when the amount of sample is very small

Question 11

describe the flame emission spectroscopy

Answer 11

1– instrumental methods used for identifying metal in a solution are measuring their concentration
2– spectroscope measured the exact wavelength of the light emitted by a metal ion
3-that allows definite identification – sometimes colours are difficult to distinguish
4-concentrations are found by measuring the intensity of light. The more intense light, the greater the concentration of the metal ion in a solution
5-from the intensity versus concentration graph you can read of a relevant concentration while you are given intensity

Question 12

what are cations and anions

Answer 12

Passions are the positive ions and ions are negative ions