# Unit 2 ## Questions to Ask Ms.Keras 1. How do you tell the difference between mechanical mixtures and a mixture/solutions? ## Page 178, Questions 3 - 10. Alloys: When two or more types of metals are mixed together. Solder Materials: Used to join together metal components, such as wires in electrical circuits and copper pipes in building, like glue. 2. **Use the particle theory to explain why water changes from a solid to a liquid when it is heated.** As water is heated, the particles or atoms gain energy, thus begin to spread apart and moving quicker, and when particles are spread decently apart, that state is called a liquid state. 3. **Give 3 examples of a pure substance** 1. Water 2. Milk 3. Apple juice 4. **Give three examples of a mixture** 1. Soup 2. Cereal with milk 3. Granorla Bar 5. **Describe a Mechincal Mixture** A mechinal mixture could be something like a cereal with milk, where you can see the cereal and milk easily. 6. **Describe a Solution** A solution could be something like apple juice, where there are different types of particles present, but are evenly mixed. 7. **Use a Venn diagram to compare mechanical mixtures and solutions** |Mechnical Mixtures|Both|Solutions| |:-----------------|:--:|--------:| |Apple Juice| 8. **Identify each of the following as a mechanical mixture or a solution** a. a pane of clear glass. **Solution** b. chocolate chip ice cream. **Mechanical Mixture** c. clear apple juice. **Solution** d. a pizza. **Mechanical Mixture** e. garbage in a garbage can. **Mechanical Mixture** 9. **What kind of alloy makes an effective solder material?** Tin and lead make an effective solder material, as it is fluid at high temperatures but solidifies quickly. 10. **Lead is not often used in solder anymore. Explain why not.** As lead is a heavy metal, it causes radioactive damage to humans, such as brain damage, which makes it harmful and unsafe. ## Pages 182 Questions 1 - 5 1. Are qualitative properties and physical properties basically the same thing? 1. **Explain the difference between a qualitative property and a quantitative property** A qualitative property is a property that is of the **qualities** of an thing, for example, metal, which is very shiny and hard. A qualitative property cannot be measured. A quantitative property is something that can be measured, like the temperature of the metal, the mass or size of the metal. 2. **A student recoreded the following observations about a T-shirt. Classify each observation as a qualitative property or a quantitative property, and give reasons for your answers** a. It is red and grey in colour. **Qualitative**, as it cannot be measured and is a quality of the object. b. It is 60 cm long. **Quantitative**, as it its measured in cm and is the length of the object. c. It is soft and strectchable. **Qualitative**, it is a property of the material. d. It will shrink in 70o water. **Qualitative**, it is a property of the material. **Ask MS KERAS** 3. **What physical properties are important for the materials used to make mountain bikes?** The bikes should be light weight, hard, durable and comfortable. 4. **List four physical properties of each of the following** * a piece of copper wire 1. its shiny 2. hard 3. bendable 4. smooth * 500 g of butter 1. soft 2. easy to cut through 3. really creamy 4. smells like cheese and milk * a glass of milk 1. opaque 2. white 3. liquid 4. non-viscous * a candle 1. hot 2. bright 3. waxy 4. soft * a piece of aluminum foil 1. shiny 2. smooth 3. grey 4. solid * a spoonful of sugar 1. powdery 2. white 3. sweet 4. solid * toothpaste 1. somewhat viscous 2. opaque 3. taste like the flavour of the toothpaste 4. squishy 5. **In each of the situations below, it seems that a new substance may have been produced. Explain why each situation represents a physical change.** * A tailor makes a new suit out of a piece of fabric - it is still a piece of the same fabric, thus no new substances have been produced, this is a physical change. * A chef makes a salad out of lettuce, tomatoes , and cucumbers - This is a mixture of different substances, but no new substances have been created, this is a physical change. * A mechanic builds a boat engine out of a lawnmower - The mechanic's lawnmower are still made of the same parts of the boat engine, thus no new substance was created. * A chemist boils slat water until only salt crystals are left. - The water evaporated but the salt was already present in the water, thus its a pyhsical change. * A child makes juice by adding water to juice concentrate - Juice already contains water, and adding more water just water downs the solution, but does not create a new substance. ## Pages 186 Questions 1 - 7 1. **Describe the diference between a physical change and a chemical change** In a physical change, no new substance is created, while a new substance is created in a chemical change. 2. **Explain why water freezing is not a chemical change.** As freezing water is just changing the state of water, water is still water, so there has been no new substance created. 3. **Classify each of the following as a physical or a chemical property** - metalic lustre **CHEMICAL** - boiling point **PHYSICAL** - explodes when ignited **CHEMICAL** - changes colour when mixed with water **CHEMICAL** 4. **Classify each of the following as a physical change or a chemical change. For each chemical change, explain how you can tell that a new substance has been formed** - Water boils and turns into steam - Physical change, there is not new substance - Wood is sawed and made into a toy box - Pyhsical change, the toy box is still made up of the same wood - Firewood burns and ashes remain - Chemical change, the ashes are the new substance - Orange drink crystals are stirred into a pitcher of water - Physical change, there is no new substance being created. - Sugar eggs, and flour are mixed and baked into cookies - Chemical change, the cake is the result of the ingredients reacting with bacterias and each other 5. **What evidence is there that a glowstick works as a result of a chemical change?** The glowstick glows due to the two chemicals at both ends meeting each other, which a new lumious liquid is made. 6. **When a candle is lit and allowed to burn for 15 minutes, some wax drips and colelcts at the base of the candle, and the candle becomes shorter** - Did you observe any physical changes? Explain - yes, as the candle got shorter due to the flame buring it off. - Why did the candle become shorter? What happened to the missing section of the candle - the missing section of the candle turned into liquid due to the heat melting it. - Did you observe any evidence of chemical change? - **ASK MS KERAS** 7. **Think about each of the following situations and describe one chemical change that is occurring. provide evidence of the chemical change** - A driver starts the car in the drive way - The gasoline is being burned of to created electricity, and produces fumes that exit the car. - A bathroom cleaning product removes a stain in the sink - The chemicals in the product reacts with the stain, and the result is the removal of the stain. - Bubbles form when baking soda is mixed with lemon juice - The bubbles are the result of the chemical change - Cookies baking in the oven give off a delicious aroma - The ingredients are reacting with the heat to create the smell. - A match is struck and ignites - The friction of 2 substances sets off a chemical reaction that allows the match to light on fire - Bleach turns a red towel white - The bleach chemicals react with the pigments in the towel, resulting in the removal of the colour of the towel. - A banana tastes sweeter as it ripens - The chemicals in the banada react to heat and age, producing glucose, which makes it sweeter. ## Pages 215 Questions 1-10 Metalliod: an element that has properties of both metals and non metals Non metal: an element, usually a gas or a dull powdery solid, that does not conduct heat or electricity. Element: a pure substance that cannot be broken down into a simpler chemical substance by any physical or chemicl means Compound: a pure substance composed of two or more different elements that are chemically joined