Microflora – natural bacteria that lives on the skin.
Solution – Homogenous mixture Eg. Salt water
Suspension – Substance with another substance suspended in it. The particles are big enough to see with the naked eye Eg. Sand in water. Colloid – Mixture involving a suspended substance inside another. However, particles take longer to settle and sometimes to not settle. Emulsion –
Practical Notes 9.2
* Process and analyse information to identify the range of chemicals used in everyday living including: – Detergent
– Metal cleaner
– Body hygiene chemicals
And outline any precautions that may be needed in the use and handling of these chemicals.
Types of chemicals used in everyday living| Definition| Active Ingredients| Element/Compound/Mixture| Safety Advice| Detergent| A water-soluble cleansing agent that combines with impurities and dirt to make them more soluble and differs from soap in not forming a scum with the salts in hard water| | | Use sparingly or use protective equipment| Lubricant| A substance, such as oil or grease, used for minimizing friction, esp. in an engine or component| | | Use little in case of slippery surfaces| Pesticide| A substance used for destroying insects or other organisms harmful to cultivated plants or to animals| | | Protect pets from pesticide| Solvent| A liquid, typically one other than water, used for dissolving other substances| Nail polish remover (ethylacetone and isopropy alcohol)| | Highly Flammable| Metal Cleaner| General cleaning or degreasing of metallic components or assemblies| | | High levels of toxicity | Body Hygiene chemicals| Substances that are used to clean the body| | | Bad for skin| Cosmetics| A product applied to the body, esp. the face, to improve its appearance| | | Use in excessive amounts can change pH |
* Use first-hand or secondary sources to gather, process, analyse and present information to identify examples of suspensions and colloids and outline one advantage of a mixture being in each form Substance| Appearance of shaking and standing| Can be separated by filtration| Type of mixture| How is it useful?| Hairspray| Shaken – sprays as a mistStanding – liquid | No| Suspension| Allows the substance to be applied easily| Salad dressing| Shaken – mixed liquidsStanding – Forms phases or layers| No| Suspension| | Mayonnaise | Shaken and standing – homogenous | No| Emulsion | | Whipped cream| Shaken – turns from a foam into a liquidStanding – will eventually become a liquid| No| Colloid| |
* Plan, select appropriate equipment orresources for and perform a first-handinvestigation to produce a range ofsuspensions and colloids that are usedby consumers including: – Beaten or whisked eggs
– Salad dressing (oil/vinegar)
Equipment: bowl, eggs, whisk
Method: Crack the eggs into a bowl and whisk vigorously until completely mixed
Equipment: ¾ cup salad oil, ¼ cup white wine vinegar, salt and pepper Method: Place all the ingredients in a blender and mix for about 10 seconds or until fully combined. Transfer to a glass bowl and let stand for 30 minutes to let the flavors meld. Give the dressing a good whisk immediately before serving.
Equipment: 2 egg yolks, 340 ml of vegetable or olive oil,1 - tbsp of lemon juice, 1 - 2 tsp of Dijon mustard and salt and pepper Method:
1) In a large mixing bowl whisk together the egg yolks with a pinch of salt. 2) Add one drop of oil to the egg yolks and whisk together with an electric whisk. 3) Continue to add one drop of oil at a time, whisking continuously until the mixture begins to blend together and thicken. The process is to add one drop of oil and then blend it in before adding the next drop. This will take several minutes. 4)...