Formulae, Equations And Amounts Of Substance

Question 1

atom

Answer 1

The smallest unit of an element that can exist

Question 2

molecule

Answer 2

The smallest part of an element or a compound which can exist alone under normal conditions.

Question 3

ion

Answer 3

An atom or group of atoms possessing a negative charge

Question 4

element

Answer 4

A substance containing just one type of atom

Question 5

compound

Answer 5

A substance that contains different elements that have been chemically combined

Question 6

empirical formulae

Answer 6

The simplest ratio showing the different types of atom present in a substance

Question 7

molecular formulae

Answer 7

The actual numbers of each type of atom in a molecule of the substance

Question 8

avagadros constant

Answer 8

6.02x10 23 number of particles in one mole of a substance

Question 9

moles equation

Answer 9

mass/relative atomic mass

Question 10

moles equation for molecules

Answer 10

mass/molar mass

Question 11

moles equation for solution

Answer 11

concentration x volume

Question 12

moles of gas

Answer 12

volume/24

Question 13

moles of gas at any temperature and pressure equation and units

Answer 13

n = PV / RT
n=moles
P=pressure in Nm-2 or Pa
V= volume in m3
R=gas constant
T=temperature in K

Question 14

degrees Celsius to kelvin

Answer 14

+273

Question 15

gas constant

Answer 15

8.314 JK-1 mol-1

Question 16

litmus colour change

Answer 16

blue in alkali

red in acid

Question 17

methyl orange colour change

Answer 17

yellow in alkali

red in acid

Question 18

Phenolphthalein colour change

Answer 18

pink in alkali

colourless in acid

Question 19

percentage error equation

Answer 19

Apparatus uncertainty/Amount being measured x 100

Question 20

why may the apparatus uncertainty be doubled

Answer 20

eg. using a burette you measure initial and final volume

Question 21

percentage yield equation

Answer 21

Mass of material produced/Theoretical maximum mass which could be produced x 100

Question 22

factors effecting error

Answer 22

larger volume less uncertainty

decimal places

Question 23

percentage atom economy

Answer 23

Molar mass of useful product/Total molar mass of starting materials x 100

Question 24

no of atoms

Answer 24

avagadros constant x moles