Objectives Flashcards
What is a chemical question?
A chemical reaction produces a new substance and is usually difficult to reverse.
Define the term rate.
The rate of reaction is the measure of the amount of reactants being converted into products per unit time.
Reactions occur whenever new substances with different properties are formed.
Explain, using the particle theory, how the rate of a reaction can be changed by
altering the following conditions:
(i) Temperature
At higher temperatures, particles move faster, increasing the number of collisions per unit time, as well as the force (energy) of collisions. Both factors increase the likelihood of successful collisions thus increasing the reaction rate (and vice versa)
Explain, using the particle theory, how the rate of a reaction can be changed by
altering the following conditions:(ii) Surface Area
The greater the surface area, the faster the reaction rate. By increasing the surface area of a substance, more particles are made available for collisions per unit time. This increases the likelihood of successful collisions and thus the reaction rate (and vice versa).
Explain, using the particle theory, how the rate of a reaction can be changed by
altering the following conditions:
(iii) Concentration
Concentration is a measure of the number of particles per unit volume. The higher concentration of a reactant usually increases the reaction rate. This is because there are more particles per unit volume which means particles are closer together, increasing the number of collisions per unit time. This increases the likelihood of successful collisions snd thus the reaction rate (and vice versa).
Describe the effect of a catalyst on the rate of a reaction.
Catalysts speed up reactions (Inhibitors slow them down) without being used up in the reactions themselves.
Enzymes are biological catalysts which speed up or slow down reactions without being used up themselves (eg saliva breaks down starch into simpler sugars).
Collect, process and analyse data to from a controlled experiment, then evaluate
the method suggesting improvements.
Have a look at the sheet done in class about temperature and your own prac.
Balance chemical equations of different types of reactions
do qs in booklet
Predict the products (names and chemical formulae) of a chemical equation
given the reactants (only single replacement, combination, and combustion). State symbols not required.
do qs in booklet
State what are in galvanic cells
In galvanic cells: there are two half-cells each half cell has a conducting electrode immersed in an electrolyte in which ions move. Each electrode is connected by a wire through which electrons move (an electric current) each electrolyte is connected by a salt bridge which completes the circuit by allowing ions to move.Oxidation occurs in one half cell (anode) while reduction occurs in the other (cathode) the anode is negative, and cathode is positive
electrons move in the external circuit from the anode to the cathode chemical energy is converted to electrical energy (ie. a chemical reaction produces electricity).
Identify, label or draw all of the above features on a given a diagram of an
operating galvanic cell.
draw galvanic cells
Explain that oxidation is a process in which electrons are lost and that this
always occurs at the electrode called the anode (an equation can be written
showing this loss).
Oxidation is a process in which electrons are lost and always occurs at the electrode called the anode (an equation can be written showing loss).
Explain that reduction is a process in which electrons are gained and that this
always occurs at the electrode;’ called the cathode (an equation can be written showing this gain).
Reduction is a process in which electrons are gained and always occurs at the electrode called the cathode ( an equation can be written showing this gain).
Appreciate that oxidation and reduction always occur together.
Oxidation and reduction always occur together.
Investigate the relationship between metal activity and galvanic cells.
Given a metal activity series: determine which cell would undergo oxidation/reduction
The more reactive metal will be oxidised (lose electrons to become ions in solution.This electrode will have a negative charge.
If the metal is nearer to the top or whichever way show higher reactivity: it means it is more reactive qnd therefore the negative eledtrode (anode).
The less reactive metal ions will be reduced (gain electrons to become the solid metal atoms). This electrode will have a positive charge.
If the metal is further from the top or which way showing less reactivity: it means it is less reactive and therefore is the positive electrode (cathode).
The negative electrode will undergo oxidation (anox). The positive electrode will undergo reduction (redcat).
However it is always in comparison to each other.
Write the equations for the redox reactions occurring in simple metal half cells connected together. Explain the variation in voltage difference for different metal combinations used in galvanic cells.
To write the redox (reduction and oxidation) equations have a look in booklet. The charge of the element will be the number of electrons in the equation and remembered to included symbols and states.
THE FURTHER APART THE METALS ARE ON THE REACTIVITY SERIES, THE GREATER THE VOLTAGE PRODUCED.
