Question | Answer |
A piece of zinc is placed in Cu(NO3)2 solution. Write 2 half equations and a net equation. | Zn(s)--->Zn2+(aq) + 2e- (oxidation)
Cu2+(aq) +2e- ---> Cu(s) (reduction)
(net equation) Cu2(aq)+ +Zn(s)---> Cu(s)+Zn2+(aq) |
How do chemical reactions produce electricity, what does it have to be connected to? | A galvanic cell, external circuit |
In a galvanic cell, what is the purpose of a simple wire? | Allows the flow of electrons and connect the electrodes to an external circuit. |
What does the voltmetre measure? | Potential difference between two half cells in volts. |
What is the potential difference? | The driving force of electrons. |
Give a definition for a galvanic cell | An external circuit that transfers chemica reactions into electrical energy by conversion. |
Draw a diagram of a Zn half cell in NO3 and Cu half cell in NO3. | na |
Which electrode does oxidation occur? | Anode |
Which electrode does reduction occur? | Cathode |
What is an electrode? | The are the conductors of a cell, often metal strips that get connected to an external ciruit. |
What is an electrolyte | A solution that conducts electricity |
Define redox reaction and they are also known as______? | Reactions that involve the transer of electrons and are both the processes of oxidation and reduction. Also known as displacement reactions. |
What is the salt bridge saturated with? | KNO3, Potassium Nitrate |
What are factors that are considered when choosing the salt bridge's saturation solution? | - Must be soluble
- Must not react with any other ions in solution |
The more active metal would most likely _____ other metals from a solution of its ions | Displace |
Oxidant | The species that causes another specie to oxidise. The oxidant itself, reduces. |
Is the oxidant the less active metal? | Yes |
Reductant | The species that causes another specie to reduce. The reeductant itself, oxidises |
Are reductants more active? | Yes |
Reductants are also known as: | Reducing agents |
What do oxidation states determine? | Whether an oxidation or reduction has taken place within a reaction. |
How are oxidation numbers assigned? | Using roman numerals. They are simply the charges on the ion. |
What is the oxidation number that elements have? | 0 |
What of the oxidation no. of a neutral molecule | 0 |
Cl2 oxidation number | 0 |
H20 oxidation number | 0 |
CO3^2- oxidation number | -2 |
Oxidation states: how do you know when oxidation has occured within the chem equation? | the oxidation state increases |
Oxidation states: how do you know when reduction has occured within the chem equation? | the oxidation state decreases |
Account for one observation when a zn half cell is connected to a cu half cell and explain why this occurs | the salt solution of cu will fade into a paler blue because the cu electrode reduces due to
zn being the reductant. When it reduces, the cu2+ ions are being removed from the solution and the cu2+ ions are what causes the strong blue colour. |
Account for another observation when a zn half cell is connected to a cu half cell | red brown deposit forms on the cu electrode as the cu ions in solution are being displaced as it reduces and transforms into cu metalic |
Which way does the anions move in a galvanic cell? | from the cathode to the anode |
Which way do the cations move in a galvanic cell? | from the anode to the cathode |