Metals and their reactions Y8

Página 1

Metals and their reactions:

The reactivity series:

Most reactive: Potassium

Sodium

Magnesium

Aluminium

Zinc

Copper

Iron

Silver

Least reactive: Gold

Displacement reactions:

A displacement reaction happens when a element that is more reactive than the compound e.g. Iron+Silver Nitrate and Potassium+Gold nitrate

There would be no reaction if the metal is less reactive then the compound e.g. Gold+ Iron Nitrate and Silver+Sodium nitrate

Metals reaction with oxygen:

-reactions with metals are called oxidations

-Products of metal reactions are called oxides

-The general word equation for oxidation is:

Metal+oxygen=Metal oxide

Examples

-Sodium: burn very quickly even after heating. The product is Sodium peroxide(a pale yellow powder)

-Magnesium: Burns easily with a brilliant white flame. The product is Magnesium oxide(grey-white powder).

-Copper: Does not burn, but a black layer is formed on the surface of the metal.The product is Copper oxide(black oxide)

-Gold: No reaction, even with strong heating

Reactions with water:

If a reactant metal, e.g. sodium or calcium, is placed in water, it will react vigorously to form the hydroxide.

e.g. water+sodium=sodium hydroxide+hydrogen

This reaction is strongly exothermic and the thermal energy ignites the H. The reaction of potassium with water is even more interesting

Less reactive metal react with steam to form the oxide and hydrogen: Water+metal=metal oxide+hydrogen

This occurs with Mg, Fe, Al, and Zn

H2O+Mg=Magnesium Oxide+H

Some metals don't react with water, while some have to be kept under a layer of oil!

Examples:

Sodium: Reacts very violently and reacts with water. Equation: H+sodium hydroxide soloution

Calcium:Reacts quite quickly. Equation: H+Calcium hydroxide in solution

Magnesium: Reacts slowly with water, but quite vigorously with steam. Equation: H+solid Magnesium Hydroxide

Iron: No reaction with cold water. Equation: H+ solid iron oxide

Copper: No reaction

Gold: No reaction

Metals and acid:

Acids are compound and include hydrogen in their stucture. When a metal reacts with an acid, the metal replaces H and produces H gas. As well as H, another product, called a salt, is produced.

Most metals react with acid. E.g. if Magnesium, is put into HCI, this reaction take place

Hydrochloric acid+magnesium=Magnesium chloride+hydrogen.

General word reaction is: Acid+Metal=Salt+Gas given off.

E.g. of metals reacting with dilute HCI:

Magnesium: Reacts very quickly.Products are Hydrogen gas+magnesium chloride in solution

Zinc: Reacts slowly. products are H gas+zinc chloride in solution

Iron: Reacts slowly, unless liquid is warmed. Products are H gas+iron chloride in a solution

Copper: No reaction

Gold No reaction

E.g. of different metals reacting with sulphuric acids:

Magnesium: Reacts very quickly. Products are H gas and Magnesium sulphate in solution

Zinc: Reacts slowly. Products are H gas+zinc sulphate in solution

Properties of Metals:

High Density

Strong

Malleable

Conductor of Electricity

Tests

For CO2: Put the gas into limewater. CO2 turns cloudy when it enters water

For H: Light a burning splint. Put match in test tube and if Pop sound is heard, that means it contains H.

Página 2

States of Matter:

Changing States:

All matters on earth are placed into 3 groups:

Solids

Liquid

Gases

These three groups of materials have different properties depending what they are used for

The most important ones are:

Whether or not they can flow. Gases and liquids flow, but solids don't flow

Whether or not a material can change shape. Solids keep the shape they are in, liquids change shape to match the shape of the container they are in, and gases spread to fill out any space they can reach

Whether or not the material can be squeezed to change it volume.

Matter is the scientific word used to describe all of the different substances on earth.

Because these temp. are always the same for one particular substance, they can be counted as properties.

Like other properties, they can help us to explain what they are used for.

Página 3

Experiments of evaporation(in states of matter).:

The amount of stuff a substance has is its mass. We can measure mass using a electronic top pan balance (A weighing machine).

We can measure changes in the mass of a certain volume of water and then calculate how much water is lost by evaporation.

Página 4

Periodic table of elements

Página 5

Seperation Techniques:

What is Sepearation:

We often want to separate different materials in one mixture

We only do this because one matterial is very useful for a particular reason e.g. getting pure drinking water out of sea water.

There are lots of ways to seperate materials

Question to ask:

Do all of the materials have the same solubility

Do all the materials have the same boiling points?

Are some of the materials solid while the others are liquid

Do any of the materials have special physical properties that none other has

Separating a solid from a liquid: Filtration:

A filter is a layer with tiny, tiny holes in it.

The tiny holes allow small particles to pass through, but the larger particles stay back.

Many filter are made for paper, hence the name filter paper, and these can hold back very tiny particles

Using filter paper is very important in sicentific experiments0

Seperation solis and water: Evaporation:

We can seperate an insoluable substance using filtration from a liquid but not from a solid and liquid dissolved together.

We use evaporation

Página 6

Seperation Techniques cont.

Evaporation takes place if the liquid is left to stand in a warm place

Evaporation speed up when the solution is gently heated

Página 7

Seperation of a solvent from a solution: Simple Distallation

Simple distalltation can be perfrormed using the appartus below

The water vapour is drected into a water cooled condenser

This piece of apparatus has a central heating tube for condensing the solvent and an outer tube that carries cold water

It is effecient at cooling the vapour

The condenser is known as the Liebig condenser

This can be described below

Chromotoragraphy

Chromotgraphy can be used to find a baseline drawn in a mixture

Steps:

A spot of a mixture is placed on a baseline drawn on a piece of chromatography paper. The baseline is drawn in pencil, or the colors of the baseline will interfere the result!

A seperatinig substance is placed in a jar and the sample paper is allowed to stand in the solvent, until the solvent reaches the top of the piece of paper

The separating solvent runs up through the paper and pullls the substances up the spot. The most soluble substance travels furture up the paper and the least soluable substance travels the shortest. Each driffrent dye in the colored mixture will form at a driffrent place.