15/02/201815/02/2018

States of Matter and Mixtures

W Richards

The Weald School

EdExcel 2016 Chemistry topic 2

States of Matter15/02/2018

Particle theory revisionParticle theory is all about explaining the properties of solids, liquids and gases by looking at what the particles do.

In a solid the particles ______ around a _____ position. There is a ______ force of attraction between each particle and they are very _____ together

SOLIDS

Words – strong, close, vibrate, fixed

LIQUIDS

GASES

In a liquid the particles are _____ together but can move in any direction. They won’t keep a _____ shape like _____ do.

In a gas the particles are very far apart and move _____ in all directions. They often ______ with each other and because they are far apart they can be easily _______.

Words – fixed, collide, quickly, close, squashed, solids

(zoomed out)

Energy in Solids, Liquids and Gases15/02/2018

Solid

LiquidGas

Which one is the most energetic and why?

Changes of State15/02/2018

Q. What are these changes of

state called?

5

Notice that these are “physical changes” – the chemicals are not being changed here.

15/02/2018

Properties of Group 7

Element Melting Point (OC) Boiling Point (OC)

Flourine -220 -188

Chlorine -101 -34

Bromine -7 59

Iodine 114 184

Here is some data about the group 7 elements:

Q. What state would each of these four elements be at room temperature?

Methods of Separating and Purifying Substances

15/02/2018

15/02/2018

MixturesBefore After

A mixture like this is formed when two or more elements are mixed together but NOT chemically combined.

The chemical properties of the salt and water remain unchanged.

Pure Substances15/02/2018

A “pure” substance is defined as a substance that doesn’t contain any impurities (i.e. anything other than the substance it’s supposed to be).

Are the following pure or impure?

15/02/2018

Element, mixture or compound?

Salty water Hydrogen

Hydrochloric acid

Sodium chloride (salt)

Diamond

Air

Q. Which of these substances are “pure”?

Melting Points and Mixtures15/02/2018

I’m using this distillation kit to heat up a liquid:

While doing this I found that one liquid started forming in the conical flask at around 60OC and the other at around 100OC. What was in the flask at the start?

Substance Boiling Point (OC)

Water 100

Phenol 180

Bromine 59

Ethanol 78

15/02/2018Separating Mixtures 1 - Evaporation and filtration of rock salt

In this practical we tried to separate rock salt – a mixture of ____ and sand. To do this we followed four steps:

1) We ground the rock salt using a ______ and mortar,

2) We dissolved the mixture,

3) We _________ it,

4) We evaporated the remains and the salt __________.

Words – filtered, salt, pestle, evaporate, dissolve, crystallized

Filtration can be used to remove something that doesn’t dissolve, evaporation can be used to separate something that does dissolve.

The sand didn’t _________, so we were able to filter it out. The salt did dissolve, so we had to ________ the remains to get the salt back.

15/02/2018Separating Mixtures 2 - Chromatography

R G B

Chromatography is a technique used to find out what unknown mixtures are made of. Substances are separated by the movement of a “mobile phase” through a “stationary phase”.

In paper chromatography, the _____ is the stationary phase and the ______ is the mobile phase.

Different _____ spread out and stop at different points due to their different ____ and properties. They can then be identified by comparing to standard reference materials. For each component, a _______ equilibrium is set up between the stationary and mobile phases.

Words – chemicals, paper, dynamic, solvent, sizes

15/02/2018

R G B X

Core Practical - Chromatography

Chromatography can be used to separate a mixture of different inks. Some example questions…

1 2 3 Z

1) Ink X contains two different colours. What are they?

2) Which ink is ink Z made out of?

15/02/2018

Rf valueThe Rf value is a way of measuring how far a substance has moved:

R G B

This line marks the distance travelled by the solvent

Rf value =Distance travelled by substance

Distance travelled by solvent

15/02/2018

Example questionsCalculate the Rf values of the following:

R G B

10cm

2cm

8cm

5cm

15/02/2018

Using Chromatography

Chromatography can be used to test which foods contain which ingredients. For example, consider the dye Sudan 1, which was found in 450 foods in 2005. Which dye contains Sudan 1?

Sudan 1

Dye 1

Dye 2

Dye 3

15/02/2018Separating Mixtures 3 – Simple Distillation

This apparatus can be used to separate water and ethanol because they have different _____ ______. The ______ will evaporate first, turn back into a _______ in the condenser and collect in the _______. The water remains in the round flask, as long as the _______ does not exceed water’s boiling point. This method can be used to separate any liquids with different boiling points such as the fractional distillation of ____ ___.

Words – temperature, boiling points, ethanol, beaker, liquid, crude oil

15/02/201815/02/2018Separating Mixtures 4 -Fractional distillation

Crude oil can be separated by fractional distillation as each liquid making up crude oil has a different boiling point:

Fractions with low boiling points condense at the top

Fractions with high boiling points condense at the bottom

15/02/2018

Separating mixtures summary1) A mixture containing something that DOES dissolve can

be separated using __________

2) A mixture of liquids with different boiling points can be separated using _________

3) A mixture of different inks can be separated using _______

4) A mixture containing something that DOES NOT dissolve can be separated using _________

Distillation, chromatography, evaporation or filtration?

15/02/2018

Making Dirty Water PotableOur water supplies obviously contain various microbes and dissolved substances. To be used as drinking water it has to be treated:

The Water Treatment Process

1) Sedimentation 2) Filtration 3) Chlorination

Pure water can also be produced from sea water by distillation but this is expensive.