Physical Chemistry 1

Question 1

Atomic Structure- Fundamental Particles- Developing Ideas of Atom

Answer 1

• 1661- Boyle- substances cannot be made simpler=chemical elements
• 1803- Dalton- all atoms of element=same mass and atoms could not be broken down
• 1896- Becquerel- radioactivity, particles inside the atom
• 1897- Thompson- electron, negatively charged, Plum Pudding=ball of positive charge with electrons inside
• 1911- Rutherford- most mass and all positive charge in tiny central nucleus

Question 2

Atomic Structure- Fundamental Particles- Sub-atomic Particles

Answer 2

• Proton= mass 1 / charge +1
• Neutron= mass 1 / charge 0
• Electron= mass 1/1840 / charge -1
• Protons and neutrons held together by strong nuclear force > electrostatic forces holding together electrons and protons
• Electrons found in shells

Question 3

Atomic Structure- Mass Number and Atomic Number

Answer 3

• Mass number
  Number of protons + number of neutrons
• Atomic (proton) number
  Number of protons (same as number of electrons)

Question 4

Atomic Structure- Isotopes

Answer 4

• Isotope- atoms with same number of protons but different number of neutrons
• Isotopes react the same as the have the same electron configuration
• Isotopes vary in mass number as they have a different number of neutrons

Question 5

Energetics- Exothermic and Endothermic Reactions

Answer 5

• Exothermic- when a reaction gives out heat as it proceeds
• Endothermic- when a reaction takes in heat from their surroundings ro keep the reaction going

Question 6

Energetics- Enthalpy

Answer 6

• Enthalpy change- the measurement of heat change at constant pressure
• Standard conditions- 100kPa / 298K / 1mol dm^-3 / standard states
• Exothermic=negative sign
• Endothermic=positive sign

Question 7

Energetics- Measuring Enthalpy Changes

Answer 7

• Enthalpy of formation
  enthalpy change when one mole of substance formed from its constituent elements under standard conditions, all reactants and products in standard states
• Enthalpy of combustion
  enthalpy change when one mole of substance completely burned in oxygen under standard conditions, all reactants and products in standard states
• Temperature=average kinetic energy of particles in a system
• Heat=total energy of all particles present in given amount of substance
• Enthalpy change: q=mcΔT
• Neutralisation reactions=exothermic
  acid+alkali=salt+water
• Displacement reactions=when more reactive metal displace less reactive one

Question 8

Energetics- Hess’s Law

Answer 8

• Hess’s law=enthalpy change for chemical reaction is the same, whatever route is taken from reactants to products
• ΔH1=ΔH2+ΔH3
• Enthalpy change of formation=from elements to compounds

Question 9

Energetics- Enthalpy Changes Of Combustion

Answer 9

• Enthalpy change when one mole of substance completely burned in oxygen under standard conditions, standard states
• Enthalpy change of combustion=from compounds to elements

Question 10

Energetics- Representing Thermochemical Cycles

Answer 10

• The enthalpies of all elements in their standard states, are taken as zero