Atoms and reactions

Question 1

What is an isotope?

Answer 1

Atoms of the same element with different numbers of neutrons but the same number of protons and electrons and different masses

Question 2

Relative isotopic mass

Answer 2

Mass of an isotope compared with 1/12th the mass of carbon-12

Question 3

Relative atomic mass

Answer 3

Weighted mean mass of one atom of an element compared with 1/12th the mass of carbon-12

Question 4

What is the purpose of mass spectrometry?

Answer 4

To determine relative isotopic masses and relative abundances of the isotope.
OR
Calculation of the relative atomic mass of an element from the relative abundances of its isotopes.

Question 5

Charge of a nitrate ion

Answer 5

NO3 (1-)

Question 6

Charge of a carbonate ion

Answer 6

CO3 (2-)

Question 7

Charge of a sulphate ion

Answer 7

SO4 (2-)

Question 8

Charge of a hydroxide ion

Answer 8

OH (1-)

Question 9

Charge of an ammonium ion

Answer 9

NH4 (1+)

Question 10

Charge of a zinc ion

Answer 10

Zn (2+)

Question 11

Charge of a silver ion

Answer 11

Ag (1+)

Question 12

What are spectator ions?

Answer 12

Ions present in a reaction mixture but do not participate in the reaction. They therefore have the same charge, formula and state and are present in the same quantity on each side of the equation.

Question 13

What is a mole?

Answer 13

Unit for the amount of a substance.

Question 14

What is Avogadro’s constant?

Answer 14

The number of particles per mole of a substance- 6.022x10^23.

Question 15

Define empirical formula

Answer 15

The simplest whole number ratio of atoms of each element present in a compound.

Question 16

Define molecular formula

Answer 16

The number and type of atoms of each element in a molecule.

Question 17

Define anhydrous

Answer 17

Containing no water

Question 18

Define hydrated

Answer 18

Containing water

Question 19

Define water of crystallization

Answer 19

When water molecules form an essential part of the crystal structure of some compounds

Question 20

Volume of one mole of any gas

Answer 20

24dm^3

Question 21

Volume of gas equation

Answer 21

Volume= Moles x 24(000)

Question 22

Ideal gas equation

Answer 22

pV= nRT
p- pressure (Pascals)
V- volume (m^3) 1m^3= 1000dm^3
n- number of moles
R-8.314 (J/K/mol)
T-temperature (Kelvin)

Question 23

1atm

Answer 23

101325Pa

Question 24

1 bar

Answer 24

100kPa= 100,000Pa

Question 25

Define percentage yield

Answer 25

Percentage ratio of actual yield to the theoretical yield: | Experimental yield/Theoretical yield

Question 26

Define atom economy. | What is the equation for atom economy?

Answer 26

A measure of the amount of starting materials that become useful products: Mass of desired useful product/Total mass of all products

Question 27

The higher the atom economy...

Answer 27

...the less waste is produced, making the process more economic and sustainable.

Question 28

4 common acids

Answer 28

HCl, H2SO4, HNO3, CH3COOH

Question 29

3 common alkalis

Answer 29

NaOH, KOH, NH3

Question 30

Define acid

Answer 30

A substance which releases H+ ions in aqueous solution; proton donors.

Question 31

Define base | What kinds of molecules can these be?

Answer 31

A substance which receives protons; a proton acceptor: metal oxides, metal hydroxides and ammonia

Question 32

Define alkali

Answer 32

A soluble base which releases OH- ions in aqueous solution

Question 33

Define salt

Answer 33

Any substance formed from the reaction between an acid and either a base, alkali or carbonate. The H+ion of the acid is replaced by a metal ion or NH4+

Question 34

Define strong acids and weak acids

Answer 34

A strong acid is one that ionises fully in aqueous solution. | A weak acid is one that only partially dissociates in aqueous solution. Weak acids have a higher pH.

Question 35

Define neutralisation reactions

Answer 35

Reactions in which acids and alkalis react quantitatively to form a salt, so that there are no H+ or OH- ions present in the product solution. Water is formed from these ions.

Question 36

What is titration? | Briefly describe the process.

Answer 36

A technique where a solution of known concentration (Standard solution) is used to determine the concentration of another solution. The titrant is typically added via burette to a known quantity of the analyte until the reaction is complete often using an indicator to show this .