2.3 How Much?

Question 1

Isotopes

Answer 1

Atoms of the same element which have different numbers of neutrons.

Question 2

Avogadro’s number?

Answer 2

6 x 10 ^23

The number of atoms in one mole

Question 3

Ar

Answer 3

Relative atomic mass

Question 4

Mr

Answer 4

Relative formula mass

Question 5

One mole

Answer 5

The relative atomic mass or relative formula mass of any substance expressed in grams.

Question 6

Mass (g) =

Answer 6

Moles x Mr/Ar

Question 7

Percentage yield=

Answer 7

Amount of product produced/ maximum amount of product possible x 100

Question 8

How can food be preserved?

Answer 8

By adding chemicals or additives or salts.
Freezing or cooling.
Keeping it in an inner environment (e.g air tight).
Dry foods.

Question 9

Food additive

Answer 9

A substance added to food to extend its shelf life and to improve taste/appearance.

Question 10

E number

Answer 10

The number an additive is given in Europe. The no. is part of the European coding system for additives, shows they have been approved.

Question 11

Thin layer chromatography

Answer 11

A method of separating the colours in a substance e.g pen ink. The process is carried out on a thin sheet of white silica paper.

Question 12

Silica

Answer 12

Stationary phase

Question 13

Solvent

Answer 13

Mobile phase

Question 14

Factors which affect how fast a dye will travel up the silica?

Answer 14

How soluble the pigments are in the solvent. (the more soluble, the faster they will travel)
How strong the pigments attraction to the silica is. ( stronger attraction to silica will cause dye to move slower.)

Question 15

Rf value

Answer 15

Distance moved by substance/distance moved by solvent

Question 16

What can the mass spectrometer be used to find?

Answer 16

The relative molecular mass of a compound from its ion peak.

Question 17

What is the molecular ion peak?

Answer 17

The peak with the largest mass corresponds to an ion with just one electron removed, it is always found as the last peak on the right as you look at the mass spectrum.

Question 18

yield of a reaction

Answer 18

Amount of product that a chemical reaction produces.

Question 19

Percentage yield

Answer 19

Tells us the amount of product that the reaction really produces with the maximum amount that could possibly be produced.