Daily Questions Circle the oxidized element, underline the reduced element. - PowerPoint Presentation

Slide1

Daily Questions

Circle the oxidized element, underline the reduced element.

2Sr +O

2

 2SrO

Fe

+

2

+O

2



FeO

Define what happens to elements that are oxidized and reduced. Slide2

Objectives:

C5.1 State that electrolysis is the

chemical

effect of electricity on

ionic

compounds, causing them to

break

up into simpler substances,

usually

elements

C5.2 Use the terms electrode,

electrolyte

, anode and

cathode

C5.4 Describe the electrode products,

using

inert electrodes, in the

electrolysis

of:

•

molten lead bromide

• aqueous copper chloride

• dilute sulfuric acid Slide3

Electrolysis Apparatus

Electrode

Electrode

Electrolyte

Electrode

- a

n electrical conductor which carries charge to or from a liquid undergoing electrolysis.

Electrolyte

- a molten or aqueous solution through which an electrical current can flow.Slide4

Electrolysis Apparatus

Cathode

Anode

Electrolyte

-

+

Cathode:

The

negatively charged

electrode. Attracts positively charged ions (cations).Anode:The positively charged electrode. Attracts negatively charged ions (anions).Slide5

Electrolysis only happens in:

- molten ionic liquids or

- aqueous solutions containing ions

.

There must be a complete circuit.

A lamp or

ammeter can be used to show

that electricity is flowing around the circuit.

Slide6

Electrolysis of zinc chloride

In your journal:

Describe what is occurring during the electrolysis of zinc chloride.Slide7

Demo Time

ElectrolysisSlide8

Electrolysis

Introducing electricity to a mixture can cause a chemical reaction to occur.

However, this requires that the atoms involved become ions

Define ionsSlide9

Forming Ions

Na

ClSlide10

Forming Ions

Na

Cl

Cl

-

Na

+Slide11

Bonding

The outer shell is full, but the ions are not neutral. How can neutrality be achieved?

Na

+

Cl

-Slide12

Ionic Bonding

An

ionic bond

is a strong electrostatic force of attraction between oppositely charged ions

[Na]

+

[

Cl

]

-Slide13

LET’S TRY A FEW

Lithium & Fluorine

Magnesium & FluorineSlide14

Conductivity

Conductivity is the ability of a substance to conduct electricity.

For a substance to conduct electricity, “free” electrons have to be available

Free electrons = electrons that are able to moveSlide15

Conductivity in Metals

Electrons move

Metals can be in solid or liquid form

No chemical change takes place

Examples: copper wire; aluminum panSlide16

Conductivity in Ionic Compounds

Ions move

Ionic compounds can be in liquid (molten) form or in aqueous solution

Chemical change takes place

Examples: molten lead bromide, sodium chloride solution, copper(II)sulfate solutionSlide17

Cathode (-)

(negative electrode)

Positive ions

go here (

cations

).

As

metal ions

are

positive

, they go to the

cathode

.

Ions gain electrons. They are

reduced

and become

neutral atoms

.

Anode (+)

(positive electrode)

Negative ions

go here (

anions

).

As

non-metal ions

are

negative

, they go to the

anode

.

Ions lose electrons. They are

oxidised

and become

neutral atoms

(which react together to form molecules).

At the electrodesSlide18

Electrolysis of Copper chloride

Electrolyte:

CuCl

2

(

aq

)

+

-

In your journal:For the electrolysis of copper chloride:Identify the ions present in the electrolyte.Describe the movement of ions.Slide19

Electrolysis of solutions –

Cathode

For solutions of highly reactive metals:

Hydrogen

gas, not the metal, is produced at the

cathode

.

For metals that are

more reactive than hydrogen, the metal will stay in the solution and hydrogen gas will be produced.Slide20

Electrolysis of Solution -

CathodeSlide21

Electrolysis of

solutions-

Anode

The product at

the

anode

depends on:

The

negative anions

present in the solution.Slide22

Homework:

Read the lab report

Grade based on the rubric provided

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