Chapter 3- amount of substance

Question 1

Define mass number

Answer 1

the total number of protons and neutrons in an atom

Question 2

Define atomic number

Answer 2

The total number of protons in an atom

Question 3

Define Isotopes

Answer 3

A version of an atom with the same number of protons and electrons but a different number of neutrons

Question 4

Define cations

Answer 4

positive ions

Question 5

Define anions

Answer 5

negative ions

Question 6

Why do isotopes react in the same way to one another

Answer 6

Because they have the same number of electrons in their outer shells

Question 7

Define Relative Isotopic Mass

Answer 7

The mass of an isotope relative to 1/12 of the mass of an atom of carbon-12

Question 8

Define Relative Atomic Mass

Answer 8

The weighted mean mass of an atom of an element compared to 1/12 of the mass of an atom of carbon-12

Question 9

Relative Molecular Mass

Answer 9

The sum of all of the relative atomic masses of all the elements in a molecule

Question 10

Relative Formula Mass

Answer 10

The sum of all the relative atomic masses of all of the elements in an ionic compound

Question 11

what is the relative mass of a proton, neutron and electron

Answer 11

1 1 1/1836

Question 12

What can avogadros constant be used for?

Answer 12

to calculate the number of atoms present in a certain molecule to calculate the number of moles from the number of atoms

Question 13

What is the equation linking avogadros constant and number of atoms

Answer 13

moles = number of atoms / avogadros constant

Question 14

Define stoichiometry

Answer 14

The ratio of the amount of each substance in an equation - moles

Question 15

Percentage yield equation

Answer 15

Percentage yield = (actual yield / theoretical yield ) x100

Question 16

Explain the steps to work out the reacting ratio to work out the mass of a product when a reactant is reacted

Answer 16

1) calculate the moles of the known mass 2) work out the moles of the unknown mass by using the ratio 3) work out the mass of the unknown

Question 17

Define the empirical formula

Answer 17

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

Question 18

How do you work out the empirical formula? (steps)

Answer 18

1) assume the masses of all the elements (off the percentages usually) 2) calculate moles of each element 3) divide by the smallest mole figure 4) multiply to get a whole number if u dont have one 5) write the empirical formula

Question 19

What is the equation for percentage atom economy?

Answer 19

Mr of desired product/ mr of total reactant * 100

Question 20

State the ideal gas equation

Answer 20

pV = nRT

Question 21

State the gas equation when at room temperature and 24 atmospheres

Answer 21

Moles= volume 24 Moles = volume 24000