Acids and bases and reactions

Question 1

Properties of acids

Answer 1

-taste sour
-corrosive
-indicators to change colour
-can conduct electricity

Question 2

Properties of bases

Answer 2

-taste bitter
-slippery
-corrosive
-react with acids=water
-can conduct electricity

Question 3

Define indicator

Answer 3

Determine whether a solution is an acid or base

Question 4

What was arrenhenius’s theory?

Answer 4

Acid dissociates in solutions to produce hydrogen ions
Bases ionise in solutions to produce hydroxide ions

Question 5

Limitations to the theory

Answer 5

-substances may not have OH formula but can still form OH solutions
-rules on work in solutions in water
-reactions such as HCL+NH3–>NH4CL are unexplained
-not all salts are neutral

Question 6

Define electrolytes

Answer 6

Liquids that can conduct an electric current
-must form ions to conduct when dissolving in water

Question 7

Relationship between conc and electric current flow

Answer 7

greater conc of ion= bigger flow of electric current

Question 8

Ionisation in acids (weak and strong)

Answer 8

strong: all acid molecules are fully ionised
weak: partially ionised

Question 9

Ionisation in bases (weak and strong)

Answer 9

weak: partially dissociate or ionise
strong: fully ionise or dissociate

Question 10

Define pH and it’s trends

Answer 10

Measure of a solutions acidity
-generally falls as hydrogen ions increase
-acidic solutions < pH 7
-base solutions > pH 7
-greater acidity = lower pH
-every change in pH = 10 fold change in H+

Question 11

Types of reactions and their equations

Answer 11

1. Neutralisation
   acid + water –> salt + water
2. Acid and metal
   acid + water –> salt + hydrogen gas
3. Acid and carbonate
   acid + carbonate –> carbon dioxide + salt + water
4. Base reaction
   acid + ammonium salt –> salt + ammonia + water

Question 12

strongest acids

Answer 12

-hydrochloric acid
-hydrobromic acid
-chloric acid
-sulfuric acid
-nitric acid
-hydroiodic acid

Question 13

What is instantaneous rate of reaction?

Answer 13

the change in concentration of an infinitely small time interval.

Question 14

Define collision theory

Answer 14

For reactions to occur reactant molecules must collide:
-with sufficient activation energy to disrupt bonds
-correct orientation suitable for bond breaking

Question 15

Define activated complex (look at example graphs)

Answer 15

-highest energy
-bond breaking/forming
-arrangement of atoms is unstable
-exists prior to reaction ending (instant)

Question 16

What do successful collision depend upon?

Answer 16

-total number of collisions
-percentage of collisions which are successful

Question 17

Relationship between reaction rate and nature of reactants

Answer 17

-involves bonding arrangement/breaking =likely to be slow at room temp
-no bond breaking = rapid at room temp

Question 18

Relationship between conc and reaction rate

Answer 18

-conc increase = increase reaction rate
-increased conc= increase particles per unit volume available to collide
-more particles collide per unit time
-more collision therefore more successful collisions per unit of time
-increased reaction rate

Question 19

Relationship between sub-division and reaction rate

Answer 19

Smaller pieces exposes more reactant to surface = surface area with smaller particles= larger SA
-cutting up increase sub division
-more reactant particles = exposed surface
-more collisions per unit time
-more collisions= more successful collisions per unit of time
-increase reaction rate

Question 20

Relationship between temperature and reaction rate

Answer 20

-temp increases will increase the average kinetic energy of particles
-increases the number of particles with sufficient activation energy
-more particles with sufficient activation energy= increase proportion of successful collisions
-increase reaction rate
or
-increase Ek increases the speed of particle movement
-increase number of collision per unit time
-increase proportion of successful collision
-increase reaction rate

Question 21

Relationship between catalyst and reaction rate

Answer 21

-reducing activation energy cause more particles to have sufficient energy
-increase in particles with sufficient energy = more successful collisions per unit of time
-increase reaction

Question 22

Define catalyst

Answer 22

Substance providing an alternative reaction pathway with lower activation energy
-they are unchanged in reactions

Question 23

Homogenous vs heterogenous catalysts

Answer 23

Homogenous
same physical state as reactants and products

Heterogenous
different physical state as reactants and products

Question 24

3 types of catalysts

Answer 24

-enzymes
-metal nanoparticles
-catalytic converters

Question 25

Define Enzymes

Answer 25

biological catalysts made from proteins - 1 to 100 nanometres

Question 26

How are metal nanoparticles catalysts?

Answer 26

-advantageous due to large SA to volume ratio -more reactants can access catalyst -more SA= increase collision due to available space =increase in successful reactions a small particle that ranges between 1 to 100 nanometres in size.

Question 27

How are catalytic converters catalysts? (Car exhausts)

Answer 27

-convert CO and NO into non toxic CO2 and N2 -also convert unburnt hydrocarbons into CO2 and H20 -millions of tiny pores in honey comb shape provide a large SA

Question 28

Random error is...

Answer 28

have measurement that are spread randomly above or below the true value

Question 29

Systematic errors are...

Answer 29

errors have flaws in the method or apparatus that lead to results that are either always above or always below the true value

Question 30

What is the collision theory

Answer 30

for reaction to occur -molecules must collide with sufficient activation energy to disrupt bonds -with correct orientation suitable for bond breaking

Question 31

What is evident in an activated complex

Answer 31

-highest energy -bond breaking/forming -arrangement of atoms is unstable -exists prior to instant reaction energy