My Chemical World

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# My Chemical World - PowerPoint PPT Presentation

My Chemical World. Matter. “It Don’t Matter” - Donovan Frankenreiter Chorus: I said If it don't matter to you It don't matter to me If it don't matter to you It don't matter to me. Matter. Matter is anything that has mass and volume

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### Matter

“It Don’t Matter” - Donovan Frankenreiter

Chorus:

I said If it don't matter to you

It don't matter to me

If it don't matter to you

It don't matter to me

Matter

Matter is anything that has mass and volume

Mass is the amount of material in a substance (unit: kg)

Volume is the amount of space occupied by a substance (units: L, cm3, mL, cc)

Density
• Density is the amount of mass packed into a certain volume.
• Gold more dense than feathers
• Less dense solids/liquids/gases float in more dense liquids/gases
• Density = mass (g)

volume (cm3)

• Unit: g/cm3
• Ice (0.9g/cm3) floats in water (1.0g/cm3) because it is less dense
• 1mL of water = 1g
Measuring Density #1
• Turn to pg 41 Science World 9
• Copy: title, aim, data table, Then: do the experiment
• *Complete: Questions 1-3

Marble 5.3g 30.0mL 31.9mL 1.9mL 2.8g/mL

Remember: density = mass / volume

Background: Rocks (eg Basalt) have a specific density

Question: Could we use this to identify a rock?

If Yes: How?

Example Rock Densities:

Basalt: 3.0g/cm3

Granite:

Limestone: 2.5-2.7g/cm3

Pumice: 0.2 g/cm3

Obsidian:

Schist: 2.7g/cm3

Measuring Density #2
Solids
• Particle packed tightly, Fixed pattern
• Strong forces hold the particles together
• They vibrate in fixed positions
• Examples: rubber, iron, ice, chalk
Liquids
• Particles move & slide past each other
• Particles still close but not fixed
• Weaker forces than a solid
• Examples:alcohol, gasoline, oil
Gases
• Particles are far apart
• The particles move quickly
• Almost no forces holding them together
• They collide with each other and the walls of their container
• Examples: air
Particle Theory of Matter:

1 All matter is made of particles – they are too small to see

2 There are spaces between the particles

3 There are forces holding particles together

4 The further apart the particles are the weaker the forces holding them together

5 Particles are always moving

6 At higher temperatures particles move faster than at low temperatures

Changes of State

Key:

Blue= + heat

Red = - heat

Reverse sublimation

Reverse sublimation

GAS (water vapour)

Explaining Changes of State
• When particles heat up they move faster. With enough vibration solid particles start to slip and slide past each other and they become a liquid (melting).
• With more heat the liquid particles move fast enough to leave the liquid and they become a gas (evaporation).
Cooling makes particle move slower. With enough cooling the fast moving particles in a gas slow down and come closer (condensation). With more cooling the particles stop slipping and sliding and become fixed – they are solid (freezing)
• When heated most substances expand (but the particles stay the same size). When cooled most substances contract.
Temperature During State Changes
• Turn to page 51 in Science World 9
• Explain the graph:
• What is happening between AB, BC, CD?
• What state is the wax at A,B,C,D?
• Explain the flat portion of the graph line.
• ?? Could we show this for H2O ??
Hydrogen
• 90% of universe is H
• Colourless
• 15x less dense than any other substance
• Flammable
• When burnt:

hydrogen + oxygen  water

(hydrogen means “water generating”)

• Used as a clean burning fuel (space shuttle, cars), margarine, floating weather balloons (airships use helium – not explosive)
Making Hydrogen
• Turn to pg 168 Science World 10
• Copy: heading, aim, Then: do the experiment
• Complete: Questions 1-5 (properly sketch & label for question 1)
Oxygen
• Makes up 21% of air
• Colourless, odourless
• Very reactive
• Combustion (burning) is when O2 reacts with other substances producing light & heat
• Animals need oxygen for respiration to get energy (humans use 20 litres per hour when resting)
• In space there is no oxygen so rockets need a supply of oxygen as well as hydrogen fuel
• Corrosion of metals (eg rusting) is when metals react slowly with oxygen
Making Oxygen
• Turn to pg 170 Science World 10
• Copy: heading, aim, Then: do the experiment
• Complete:
• Copy method diagram (properly sketch & label)
• Questions 1-2
Carbon Dioxide
• Odourless, colourless, 0.03% of air
• Produced in fermentation yeast use sugar and produce CO2 (bread rises, bubbles in drinks) and alcohol (wine, beer…)
• Used in photosynthesis:
• CO2 + H2O  glucose + O2
• Produced in respiration:
• glucose + O2 CO2 + H2O + energy (*ATP)
Making Carbon Dioxide
• Turn to pg 172 Science World 10
• Copy: heading, aim, method diagram
• Then: follow the method and complete all tasks with a red hand (write in your book, full sentences)
Heat & Temperature

What’s heat?

The amount of EK (kinetic energy) particles have

What’s temperature?

How hot/cold or the average EK of the particles

Heat Transfer

Heat only transfers from hotter to colder objects in these 3 ways:

Conduction

Heat energy (EK) passed on when neighbouring particles bump each other. (solids mostly)

Convection

Heat gas/liquid  less dense  rises (draws cool material toward heat source)  cools more dense  sinks (cycle repeats to give “convection currents”

Hot objects emit heat as infra-red light (travels at light speed, & through a vacuum)

Physical Changes
• Properties may change
• Substance stays the same
• No new substance forms
• Change is usually reversible
• Shape / state change
• eg: water freezing...
Chemical Changes
• Heat / light may be produced
• Can’t be easily reversed
• May be a colour change
• Bubbling / fizzing
• eg: burning wood…
Solutions
• Use the glossary at the back of the textbook to DEFINE each of the following, and give an EXAMPLE.
• Dissolve
• Solution
• Solute
• Solvent
• Soluble
• Insoluble
• Suspension
Soluble or Insoluble?
• Turn to pg 63 Science World 9
• Copy: title, aim
• Then: Part A - follow the method making sure you complete the data table recording “soluble, slightly soluble, insoluble” for all the substances supplied, repeat with ethanol instead of water for part B (pg64)
• Complete: Questions & Conclusions (pg64) FULL answers
Solubility
• Use the glossary at the back of the textbook to DEFINE each of the following, and give an EXAMPLE.
• Dilute
• Concentrated
• Saturated Solution
• Unsaturated (not in glossary)
• Solubility (+ write what generally happens to this as temperature increases)
• Super Saturated (not in glossary)
• (if you finish early add images / pictures for each)
Finding Solubility
• Solubility is the amount of solute that can dissolve in a set amount of solvent at a particular temperature.
• Eg: sugar solubility:
• 2kg per litre of water at 20ºC
• 5kg per litre of water at 100ºC (Science World 9)
• How could we find solubility?
• Solute / solvent choice?
• End point?
• Units?
Solubility of Salt

Aim: To find the solubility of salt

Method:

• Put 100mL water in a beaker (A)
• Weigh this.
• Add salt until no more dissolves.
• Weigh beaker. (B)
• Calculate B-A. This is the solubility in grams per 100mL (of salt in water)

Result:

Solubility of salt in H20 at ____ degrees Celsius: _____ g/ 100mL

Question(s)

Predict whether the solubility would increase if temperature is increased

### Separating Mixtures

Separating Suspensions
• Decanting
• Pouring off a liquid, leaving solid behind
• Centrifuging
• Spinning suspension at high speed causing solids to settle quickly. Liquid is then decanted
• Filtering
• Separating solid from liquid using a filter
• filtrate: the liquid that has passed through a filter
• residue: the solid left behind after filtering

Filtering & Decanting
• Turn to pg 68 Science World 9
• Copy: title, aim
• Then:
• Part A: follow the method
• Part B: follow the method
• Complete: Questions & Conclusions (pg69) FULL answers
Separating Solutions
• Distillation -

Separating the parts of a solution by:

• Evaporating the liquid, then:
• Condensing the liquid in a separate container
Evaporation & Distillation
• Turn to pg 71 Science World 9
• Copy: title, aim, Part A title, method diagram (label it)
• Then:
• Part A: follow the method
• Complete: Questions & Conclusions (pg72) FULL answers
• Then:
• Part B: copy title, follow method OR watch demo
• Complete: Questions & Conclusions (pg73) FULL answers
Making Crystals
• Crystals of a solute form when a solution becomes so concentrated that the solute can’t stay dissolved anymore.
• This is achieved by:
• evaporating solvent
• heating, adding solute to make the solution super saturated and then allow it to cool.
• Crystal size depends on rate of formation
• Fast: small crystals
• Slow: large crystals
5H20.CuSO4
• Take hydrated copper (II) sulphate crystals in a test tube and heat. The blue crystals in the test tube start turning white on heating. Water vapours released on heating condense on the cooler part of the test tube. Collect the water drops in a dish. The crystalline copper sulphate turns to a white amorphous form.
• Allow the white amorphous powder in the test tube to cool down and then add the water collected in the dish to it; white amorphous powder turns back to blue crystalline form.
Solar Water Distiller
• Having viewed the video you are now to get into groups of three and design a practical solar distiller.
• Complete a one page plan (aim, equipment, method) showing how you will carry this out.
• Supplied equipment. 500mL of coloured water (or water mixed with soil) + regular lab equipment (anything else must be brought in by you).
Separating Solids
• Evaporation (when one solid is soluble)

- Add water to dissolve one solid, filter. Dry the residue. Evaporate water from filtrate.

• Magnetic Separation

- If one solid is iron  use a magnet to extract it

• Density – float / sink in water

- If only one solid floats in water, add water, scoop it off water surface

• Density – gravity separation

- If one solid is quite dense, use ‘gold panning’ technique to separate dense material on bottom of container

• Sieving

- Remove larger solids from small solids (eg sieve peas out of flour)

• Chromatography

- Using capillary action and solvents to separate mixtures of different pigments (colours) of different weights.

Paper Chromatography
• Turn to pg 74 Science World 9
• Copy: title, aim
• Then:
• Copy method A diagram
• Carry out method A
• Cut up your filter paper so each group member has the results, label, glue in book
• Then:
• Copy method C diagram
• Carry out method C (do at least three strips)
• Glue one strip into your book, label it
• Then
• Exercise 9 pg 76, Challenge 4 pg77
Homeopathy
• What is it?

Homeopathy tries to treat a disease by giving heavily diluted doses of a substance that would in healthy persons produce symptoms similar to those of the disease.

Homeopathy is a form of alternative medicine, first proposed by German physician Samuel Hahnemann in 1796, that treats patients with heavily diluted preparations which are thought to cause effects similar to the symptoms presented. Homeopathic remedies are prepared by serial dilution with shaking by forceful striking, which homeopaths term "succussion," after each dilution under the assumption that this increases the effect of the treatment. Homeopaths call this process "potentization". Dilution often continues until none of the original substance remains.

Apart from the symptoms of the disease, homeopaths use aspects of the patient's physical and psychological state in recommending remedies. Homeopathic reference books known as repertories are then consulted, and a remedy is selected based on the totality of symptoms. Homeopathic remedies are considered safe, with rare exceptions. However, some homeopaths have been criticized for putting patients at risk with advice to avoid conventional medicine such as vaccinations, anti-malarial drugs, and antibiotics. In many countries, the laws that govern the regulation and testing of conventional drugs do not apply to homeopathic remedies.

Claims of homeopathy's efficacy beyond the placebo effect are unsupported by the collective weight of scientific and clinical evidence. While some studies have positive results, systematic reviews of all the published trials fail to conclusively demonstrate efficacy. Furthermore, higher quality trials tend to report less positive results, and most positive studies have not been replicated or show methodological problems that prevent them from being considered unambiguous evidence of homeopathy's efficacy.

Homeopathic remedies generally contain few or no pharmacologically active ingredients, and for such remedies to have pharmacological effect would violate fundamental principles of science. Modern homeopaths have proposed that water has a memory that allows homeopathic preparations to work without any of the original substance; however, the physics of water are well understood, and no known mechanism permits such a memory. The lack of convincing scientific evidence supporting homeopathy's efficacy and its use of remedies lacking active ingredients have caused homeopathy to be described as pseudoscience and (more plainly) as quackery by Oliver Wendell Holmes, Sr. and more recent writers.

### Notes Pages

Matter

Matter is anything that has _____ and ______

Mass is the amount of ________ in a substance (unit: _________)

Volume is the _______________ occupied by a substance (units: _______________)

Density
• Density is the __________________________.
• Gold more dense than _____________
• Less dense solids/liquids/gases ______ in more dense liquids/gases
• Density = mass (g)

volume (cm3)

• Unit: ________________
• Ice (0.9g/cm3) floats in water (1.0g/cm3) because it is less dense
• 1mL of water = 1g
Particle Theory of Matter Demos

1 All matter is made of particles – they are too small to see (seen an atom? ppt)

2 There are spaces between the particles (compression & add meths to water)

3 There are forces holding particles together

4 The further apart the particle are the weaker the forces holding them together

5 Particles are always moving (spray deod)

6 At higher temperatures particles move faster than at low temperatures (KMnO4 or food colouring hot / cold water)