Liquid to solid - freezing M D = __ V Contoh: 0.5 g 0.5cm = 1 g/cmDensity Density = Jika: 0.5 g 1 cm = 0.5 g/cmDensity Density = Fikir tentang `Volume’ Volume expand during freezing. on cooling 4° C – volume of water contract Below 4° C – volume of water expa nd Freezing point: 1. Water 0° C 2.Nafthelene - 80 ⁰ C 3.Nitrogen – 210° C Float (less density than water)
Freezing point: 1. Water 0° C 2.Nafthelene - 80 ⁰ C (boiling 218 ⁰C) 3.Nitrogen – 210° C Naftalena -Not dissolve in water Very dissolve in hot water (below boiling point)
Test presence of water Anhydrous copper sulphate (white blue) Anhydrous Cobalt chloride paper (Blue pink) The effects of impurities on the physical characteristics of water i.Boil at a temperature above 100ºC ii.freeze at a temperature below 0ºC
Rate dissolving increase with: increasing temperature of solvent (cold/heat) Increasing surface area of solute (fine/coarse) stirring Water is a universal solvent. SATURATED dissolving increase with: increasing temperature /HEAT increasing temperature /HEAT Increasing VOLUME OF WATER (solvent) Increasing VOLUME OF WATER (solvent)
Soalan PKBS B B
questions 1. Is the boiling point of water with salt higher or lower than that of pure water? 2. Do impurities increase or decrease the boiling point of water? 3. How do you test whether tap water is pure water?
SOLUTIONSUSPENSION 1. DISSOLVED IN WATER 1. DO NOT DISSOLVED IN WATER. 2. TRANSPARENT 2. NOT TRANSPARENT / OPAQUE 3. LIGHT CAN TRANSMIT 3. LIGHT CANNOT TRANSMIT 4. SMALL PARTICLES. 4. LARGE PARTICLES. 5. CANNOT SEPARATE WITH FILTER PAPER. 5. CAN SEPARATE WITH FILTER PAPER. Sugar solution, salt solution Milo solution COMPARISON BETWEEN SOLUTION AND SUSPENSION
COMPARISON BETWEEN SOLUTION AND SUSPENSION
THE IMPORTANCE OF WATER AS A SOLVENT DISSOLVES OXYGEN AND CARBON DIOXIDE FOR AQUATIC ORGANISMS. DISSOLVES OXYGEN AND FOOD SO THAT THESE CAN BE TRANSPORTED TO BODY CELL. DISSOLVES MANY DIFFERENT TYPES OF MINERAL SALTS AND THIS ENABLES THE ROOTS OF PLANTS TO ABSORB THESE DISSOLVED MINERALS. MOST CHEMICAL REACTIONS IN OUR BODY NEED WATER AS A SOLVENT.
Composition of water 1 molecule of water 2 atom hydrogen 1 atom oxygen Awas BACAAN Pada test tube…
Process - Electrolysis of water Water: H2O Panjang (anode) – Positive - oxygen The composition of water Two atom hydrogen and one atom oxygen Are chemically combines to form one Molecule of water.
Johor 2010 A. Copper B. carbon C. sulphur D. aluminium PMR 2011
Check ….apa salah …
Water Molecules Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 8
The decomposition of two water molecules. Electric current Water molecules Diatomic oxygen molecule hydrogen molecules +
Electrolysis of Water
Water Hydrogen gas forms Oxygen gas forms ElectrodeSource of direct current Electrolysis *Must add acid catalyst to conduct electricity *H 1+ water oxygen hydrogen “electro” = electricity “lysis” = to split H 2 O(l) O 2 (g) + 2 H 2 (g)
Test presence of oxygen (anode) +ve 1.burning wooden splinter – more brightly 2.glowing wooden splinter – flame/ignite/rekindless Test presence of hydrogen (cathode) -ve 1.burning wooden splinter – produce `pop sound’ – not support combustion
EVAPORATION & BOILING
EVAPORATIONBOILING Any temperatureComparison Slow process At the surface of the water Liquid changes to gasesSimilarities Heat energy is absorb Application of evaporation in daily life 1.To obtain salt from sea water 2.To dry product from agriculture such as cocoa, pepper, tea leaves and paddy. 3.To dry clothes 4.To process milk powder 1.Surface area 2.humidity 4.temperature 3.Air movement Factors evaporation
Pahang 2011 State the relationship between the rate of Evaporation and condition of cloth. …………………………………………….
ORGANIC SOLVENT SUBSTANCES THAT ARE DISSOLVES ALCOHOL CHLOROPHYLL (GRASS), IODINE, SHELLAC, VARNISH, BALL POINT PEN INK KEROSENE FRESH PAINT, OIL, IODINE TURPENTINE TAR, GREASE PETROL FRESH PAINT, OIL, TAR, GREASE, WAX, LATEX ACETONELIPSTICK AMYL ACETATE NAIL POLISH ETHYL ACETATE IODINE ETHER GREASE, OIL, FATS CITRIC ACID FRUIT STAINS LIME JUICE RUST CHLOROFORMPLASTIC MILKINK BENZENE LATEX, GREASE STAINS
acid Organic acidInorganic acid Sulphuric acid – laboratories Nitric acid – lab Hydrochloric acid – lab Carbonic acid – carbonated drinks differences Acetic acid – vinegar Formic acid – ants PMR 2011 Lactic acid – sour milk Malic acid – young apples Citric acid – limes Tannic acid – tea Tartaric acid - grapes Living thing (plants & animals) Weak acids Less corrosive Original source Strength of acids Very corrosive Strong acids Rocks and minerals Corrosive properties - fertilizers Hydrochloric acid has many uses. It is used in the production of chlorides, fertilizers, and dyes, in electroplating, and in the photographic, textile, and rubber
Test for acid Litmus paper Biru Merah PH less than 7 Universal Indicator – yellowish green to Red Test for alkali Litmus paper Merah Biru Litmus paper Merah Biru PH more than 7 PH more than 7 Universal Indicator – yellowish - Purple Bas MERAH ABCDEFGHIJKL…..
Test for acid Litmus paper Biru Merah PH less than 7 Universal Indicator – yellowish green to Red
Litmus paper Merah Biru Litmus paper Merah Biru PH more than 7 PH more than 7 Universal Indicator – yellowish - Purple Test for alkali
Milk of magnesia is a liquid used in medicinal applications as an antacid and a hydrating laxative. Also known as magnesium hydroxide or Mg(OH)2, the solution is taken orally. It is so named because it looks milky white and contains the naturally occurring mineral magnesium. The substance acts to work within six hours of a dose in adults and children to temporarily relieve occasional bouts of constipation. The original concentrated formula was concocted by a man named Charles Henry Phillips in 1880, and sold under the brand Phillips' Milk of Magnesia. Today, the rights to the name "milk of magnesia" appear to be owned by Bayer Corporation. Milk of magnesia is an alkaline suspension, meaning that it undergoes a neutralizing reaction when encountering anything acidic. Do you know?
ACIDALKALINE REACTS WITH Magnesium, Wooden Block, Meat, cloth REACTS WITH Magnesium, Wooden Block, Meat CONDUCT ELECTRICITY CONDUCT ELECTRITY SHOW THEIR PROPERTIES IN PRESENCE WATER BLUE LITMUS PAPER BLUE LITMUS PAPER Blue to Red RED LITMUS PAPER RED LITMUS PAPER Red to Blue SourBitter Burn Skin Skin Dry Slippery pH < 7 pH > 7 CorrosiveCorrosive
Any other uses of neutralisation? 1. Wasp stings are treated with vinegar 2. Bee stings are treated with bicarbonate of soda 3. What does this tell us about the pH of the bee and wasp stings?
Neutralisation Universal _______ tells us what the pH of a solution is. If the pH is below 7 we say it is an ___ and it will turn ___. If it is above 7 it will turn ___ and we say it is an ____. If the solution turns ____ we say it is _____ and it has a pH of 7. Indicator acidredbluealkali greenneutral
ACID + ALKALI Salt + Water Method - TITRATIONProcess - NEUTRALISATION More alkalin