We are going to do an investigation to find out! We have seen that strength and durability are desirable properties in some materials. Properties that describe how a substance changes into a completely different substance are called chemical properties. New properties introduced are boiling point and melting point, and these are introduced using water as example. Learners may say that something is strong when it is difficult to break. Record your measurements in a table in the space provided. These trees also use a lot of water and prevent anything from growing underneath them. a physical property that does not depend on the amount of the material. Your teacher will demonstrate how to handle the Bunsen burner safely. The following activity has another example of advantages versus disadvantages. Take the average of the number of marbles. Can you remember what properties are? Boiling is when liquid water changes to water vapour or steam. Piezoelectricity 1. Spalling resistance 11. We want things to be strong and to last long. They are not really compressible either. When ice is heated, its temperature will remain constant until all the ice has melted. What is fracking? Learners could discuss ways of ensuring the test is fair. Unit of αA is per oC. Perhaps you measured the boiling point of the water as slightly less than 100°C. (That means from weakest to strongest.). Bulk density 2. Perhaps you have had your temperature taken with a thermometer .A thermometer can be used to find out how hot or cold something is. It does not have any unite. Here is an optional, extension activity on how a thermometer works. The change in volume of an object due change in temperature is related by “Coefficient of volume thermal expansion”. The suitability of a material for a certain use is also influenced by other factors such as its cost, its colour and its texture. Do you know what those are? Next year, learners will look at the Particle Model of Matter, and within this, cover density and the contraction and expansion of materials. It is the property of a material by which it regains its original dimensions on removal of load or force. Learners could be encouraged to imagine carrying a shopping bag filled with heavy items, that would simply fall through a shopping bag that is too weak or thin. The right side of the graph, where the slope is positive, shows that the temperature was going up. Plastics are generally stronger than paper, so for a start, the testing method should allow for greater weights to be hung from the plastic strips. How would you modify the investigation to test the strength of different types of plastic? The ways we use materials and the processes we use to produce them always have an impact on the environment. They reduce the biodiversity in the area. But, in boiling, the liquid needs to be heated to reach its boiling point. Repeat steps 1 - 5 using the other end of the strip and count the marbles again. A material's property (or material property) is an intensive property of some material, i.e. Different thermometers from different batches might also give slightly different readings. These are huge piles of crushed rock left over from decades of gold mining. We have already seen how the use of materials, such as plastics and paper, has a negative impact on our environment, but what about their production? Is it a straight line? Coefficient of thermal expansion, represents the expansion in material with increase in temperature. The test tube containing the ethanol or methanol should be suspended in a beaker of tap water, and slowly heated. Water permeability 13. Plot the data on a line graph using the graph paper - each data point must be marked with a small, neat cross. If, m is the mass of material in Kg, V is the volume of materiel in meter3. Below are a number of short sentences. The concept of making predictions in science investigations is introduced here. While the water is boiling the temperature will remain constant. Below is a concept map for what we have learnt about the properties of materials. Write some of your ideas down. It is the ability of a material to attain the hardness by heat treatment processing. Discuss this with your class. strips of different types of paper (20cm x 5cm). Hygroscopicity 14. Show this temperature on the graph. Those are things like density, melting point, conductivity, coefficient of expansion, etc. Every process used to produce materials for our benefit has an impact on the environment. Boiling occurs when a liquid turns to a gas at boiling point. Some processes have a small impact and others have a large impact. The left part of the graph where the slope is positive, shows that the temperature of the water increased. For example, ask learners: "What do more marbles in the yoghurt tub mean?" Note: An exception is water which actually expands when it becomes a solid (ice). The boiling point of water at sea level is _______. Water boils at 100°C at sea level and at temperatures slightly below that at elevated altitudes. They have not yet encountered force as a concept (force is covered in Gr 9 Energy and Change) but you could encourage them to think about what they are doing when they hang the heavy marbles on the strip of paper. In this article we will discuss about the physical and mechanical properties of engineering materials. When we keep on increasing the load beyond the limit of elasticity, the material retains it molded state. Discuss this as a class and write some notes on the lines provided. You may remember that properties are distinctive characteristics that describe an object or material. At sea level (close to the ocean) water boils at 100°C. Now suppose you start heating the mixture. Learner-dependent answer based on the evidence from the investigation. Unit of αA is per oC. When an electric current is passed through it, it increases in size (up to a 4% change in volume). Boiling point is a property of a substance. Physical properties materials testing and measurement. The liquid level will rise when the liquid expands. They are mixed but they have not changed into something else. Existing models This section reviews the existing analytical models for effective physical properties of heterogeneous materials, including thermal conductivity, coefficient of thermal expansion, electric conductivity, dielectric constant (permittivity) and mechanical modulus. Does boiling have a reverse process? The thermometer usually contains some type of brightly coloured liquid. Set up your apparatus as shown in the following picture. In each case, you must complete the sentence by filling in the missing words. Play an interactive game based on the melting points of solids. The best graph is obtained when the water is stirred gently throughout; this ensures that the water is heated uniformly. When the person tried to heat the water, the kettle melted as a result of contact with the flame/heat. [1 mark]. Have you ever had your temperature taken? The gas bubbles then rise to the surface of the liquid and the liquid is said to boil. The change in length of an object due change in temperature is related by “Coefficient of linear thermal expansion”. Do you think the time required for the ice to melt would be longer, shorter or the same? Q is the amount of heat given to material in Joule. State change temperature is the temperature at which the substance changes from one state to another state. The right part of the graph where the graph is horizontal, shows that the temperature of the water did not change over time, but stayed constant. Liquids take up less space when they are cold and more space when they are warm; we say they contract when they are cooled and expand when they are warmed. Repeating an experiment and calculating an average value helps to eliminate errors, or results that arise by chance (or luck). The kettle is meant to be plugged in to heat the water. The bigger flame gives more energy to the water but does not affect the boiling point. 5. ductile: the property of a material that allows it to be drawn out into a wire. Learners may say the paper that is most difficult to tear would be the strongest. What is happening to the wax around the flame? (If you cannot get hold of marbles you could try finding small stones or pebbles that are more or less the same size. When water is boiled over a bigger flame, it will boil at the same temperature, namely 100°C (at lower altitude/at sea level). Some examples are: Ice cream, butter, and chocolate. What impact do you think this has on the environment? If you want to create a circuit for a bulb, the material that you use in the circuit to connect the battery to the bulb must have a high ________. What is room temperature? Disadvantages are unfavourable features, as can be seen in the images of plastic in the environment. Do you remember learning about the state changes in previous grades? Materials for cookware would need to be strong, rigid, and able to conduct heat. Before starting the investigation, divide the class up into groups in which they will perform the investigation and get learners to discuss the following questions first in their group to revise concepts from Gr 6. The material senses the force of an impact on the car and sends an electric charge to activate the airbag. Why do you say so? 1. Why does a plastic kettle not melt when we boil water in it? Before you start, discuss the following questions in your group: Discuss what you know about gases, liquids and solids; the three states of matter. What happened to the temperature of the water when all the ice had melted? The. Physical Properties of Solid Materials. Why do you think this is so? Is this correct? What do you notice about the ice? These can include: The two words, heat and temperature, are connected but they do not mean the same thing: Adding heat energy usually results in a temperature rise, so people often confuse heat and temperature. Diamond mines require huge amounts of diesel which produce greenhouse gases which build up in the atmosphere. in order of increasing tearing strength. What do you notice about the temperature when all the ice has melted? Fill in the missing word. Can you think of a few substances that are solids at low temperatures, but have low melting points? Learners should be encouraged at this stage to start thinking about scientific processes and products in terms of their advantages and disadvantages. If you think a statement is FALSE, you have to write a TRUE statement in its place. It denoted by “αV” The fibers cling to each other because they have tiny branches on them, that become entangled to give the paper extra strength. Would it perhaps be safer in the event of an accident? Sometimes, just the handles of the cooking pot are made from plastic or wood. Note: Learners may battle with this question so you can ask them if they think anything can grow or live on these dumps again? Boiling point is the temperature at which a liquid boils. Remember that when you want to take the temperature, the thermometer must not be touching the sides. What temperature would be reached first: 78°C or 100°C? Do all liquids boil at 100°C? Get them to mark where it is on the diagram. Tell them to bring the biggest pieces they can find. The boiling point of nitrogen is - 200°C. This is a good opportunity to introduce the notion of fair testing: As many variables as possible should be kept the same: length of the plastic strips, method of fastening the weight to the plastic strips, etc. The next question refers to a bigger flame. Latent heat is given by, Physical and Social Properties of Materials . The temperature at which ice melts is called the melting point of ice. The particles in liquids are also close to each other, but they are not in fixed positions and can move around, that means liquids can fill the container they are in. Look at the image of a gold car then answer the questions that follow. Learner-dependent answer: metals, plastics, leather, concrete and wood are all examples of materials that learners could mention. The set of characteristics that describe a material are called the properties of that material. Huge amounts of land are destroyed when mining coal. Examples include colour, hardness and smell and freezing, melting and boiling points. In this investigation, you will add the number of marbles together for each time you tested the paper strength (this was twice for each strip of paper) and then divide by 2 to calculate the average number of marbles that each piece of paper can hold before it tears. Do you think plastic is a good choice of material for making a whole cooking pot? [2 marks]. Encourage them to also think of not-so-obvious uses for old shopping bags, like making artworks or weaving mats for instance. It is defined as the ratio of density of material with respect to density of a reference material or substance. See more ideas about properties of materials, kindergarten science, science activities. Sometimes, adding substances (such as ethanol) to water can bring the boiling point down (refer to Raoult's Law). One issue to be aware of is that the suggested beverages are all solutions of substancesin water. Tip: To calculate the average of a set of numbers, you add all the numbers together and then divide by how many numbers there were in the set. Can you imagine a car made of solid gold? The boiling point of water depends on the atmospheric pressure. Learners can come up with their own reasons here. Fire resistance 8. Let's now investigate boiling and melting. This is because they might have been calibrated differently. State whether each of the following statements is TRUE or FALSE. We discussed several properties of materials in this chapter. Just a few sentences are required here. We say it makes the answer more reliable. ), How long does it take for the unknown liquid to start boiling? The common glass thermometer that you see in the image is called a bulb thermometer. But if we want to condense the water vapour, we need to cool it down (take energy out of it). How long did it take for all the ice to melt? It is denoted by ‘L’. Physical properties are based on the laws of physics that describe mass, energy, force, light, heat, electricity, and other physical phenomena. We will look more at heating as a transfer of energy next term in Energy and Change. Look at this photo of a candle burning. First, let's check if everyone knows that there is a difference between the words heat and temperature. Let's find out. When water is heated, its temperature will rise until the water starts to boil. A material's physical properties determine the physical state and appearance of different substances. Creative Commons Attribution License. Note that this is not true for all plastics. Water is a liquid at 25°C. This may help them to understand the concept of specific heat later on. The wool or fabric that the jersey is made of does not conduct heat well. Repeat this using the other strips of paper, doing each twice and taking the averages. Why would plastic shopping bags need to be strong? http://mg.co.za/article/2013-06-28-00-new-us-study-inflames-sas-fracking-feud. When lighting the burner, always light the match (or lighter) before opening the gas. Since we have no real measure of the energy added to the water, but since we do know that the energy was added at a constant rate, we can use the time that the water was heated as our independent variable. If you can, write them in the space below. Label the axis, and use minutes as units. These are the properties required to estimate the quality and condition of the material without any external force. Flammability and corrosion/oxidation resistance are examples of chemical properties. Now draw a blue line at the boiling point of water and also label this line. Paper mills use huge amounts of water, and the waste water contains many chemicals and substances which damage the environment. Unit of αL is per oC. A material’s performance depends on its physical properties, and optimizing this is the most important way to reduce your product’s environmental impact. The ice would melt at the same temperature because the melting point stays the same. When we want to measure temperature we use a thermometer. (Metals have this property.). In contrast, chemical properties are those that can only be observed and measured by performing a chemical reaction, thus changing the molecular structure of the sample. Determining the boiling point of water by another method, for instance in a pot on the stove, or in a kettle. CAPS suggests that this investigation could be performed on `other liquids' such as orange juice, apple juice and cola. 3 3. Heating the ice with a burner simply delivers the energy at a faster rate, so melting occurs sooner. A material that conducts heat well is said to have a high ________. How can we explain the term 'boiling point'? If the holes were punched at different distances from the edge, this might make some papers appear stronger or weaker than they actually are. This is because wood and plastic are not good conductors of heat, unlike metal, and so you can pick up the pot easily. to personalise content to better meet the needs of our users. Say why you think it is this substance. 2.3 Physical Characteristics . A safe way of heating ethanol or methanol to its boiling point is shown in the following diagram. Coal mining also requires large amounts of water, which reduces the water for surrounding areas. Here are some guidelines for drawing the graph: The title of your graph should be: Determining the melting point of ice. Allow learners to discuss how to test how strong a material is for a few minutes and come up with a few ideas. It is the property of a material which represents that how easily the heat can be conducted by a material. The Porosity of material represents the quantity of voids in solid materials. The phase transition between water and ice (liquid and solid water) always occurs at 0°C (in pure water). Warning: Take care when working with these substances, especially methanol, since it is dangerous. Encourage learners to write what they think of the golden car, what their thoughts and feelings are. Learners may be unsure, but you could say that the ethanol is still ethanol, it has not been changed in the process of mixing, so it will most certainly start to boil at 78°C. In the next activity we are going to explore the boiling and melting points of a few substances other than water. The mercury inside these kinds of thermometers is toxic and dangerous so they must be handled with care. The boiling point of a material is the temperature at which the liquid state of that material turns into a gas. For example, if you had 5 marbles in the first attempt, and 3 marbles in the second attempt, the average will be calculated as follows: Therefore, the paper type could hold an average of 4 marbles. You could let the learners cut the paper into strips of 20 x 5 cm each, or you could do this beforehand to save time. Learners may also remember that metals are ductile. Have you ever been so sick that you had a fever? Possible hypotheses that learners could give include stating the boiling point of water that they might know from previous knowledge. Draw a black line at this temperature and label it. For example if you leave a saucer of water out in the sun, the water will evaporate. Earlier, we saw how some of the properties of materials may be advantages under certain circumstances, but can become disadvantages under a different set of circumstances, such as plastics and other materials which, if they end up in nature, can have serious consequences and cause harm to other animals. We measure temperature with a thermometer. Weathering resistance 10. Learners can help you prepare for the activity by bringing different types of paper to school: newspaper, tissue paper, paper towel, or old magazines and gift wrap. When you write a hypothesis, you must state what you think will happen in your investigation. Materials are most of all the objects and therefore materials have its own properties. Say. What needs to happen to water to make it freeze? It is denoted by ‘S’. Make a handle for the yoghurt tub, using the string. At first, the temperature of the ice-water-mixture stayed constant, then after all the ice had melted, the temperature of the water started to go up. Take some of the ice pieces and drop them into the beaker. It is not important that learners remember these temperatures, as they will be determining them experimentally shortly. Hang the yoghurt tub from the paper clip and hold it in your hand. This will make it a fair test. A material that conducts heat well is said to have a high heat conductivity. Use the list to identify the unknown liquid. This means there may not be a big difference between the experiments carried out with ethanol and methylated spirits. Coefficient of Linear Thermal Expansion In order for water to freeze, it needs to be cooled down. These materials are widely used as sensors in different environments. 5 that the properties of a material determine what it can be used for. Melting occurs at the melting point which is 0°C. Most plastics melt easily because they melt at relatively low temperatures. What other properties of metals do you remember? Not all substances melt at 0°C either. Why do you think the person made the mistake of heating the kettle on the stove? (At higher altitudes water boils at temperatures slightly below 100°C.). We also mine and produce other metals such as chromium, platinum, as well as coal and iron ore. We learnt in Gr. Punch a hole at both ends of each paper strip. Δt is rise in temperature. Water freezes at 0°C. Write a conclusion for this investigation. Specific heat of a material is defined as the amount of heat required to increase the temperature of unit mass of material by 1oC. Bubbles of water vapour then form in the liquid and rise up. All bulb thermometers consist of a fairly large bulb, connected to a long thin tube. Possible answers are the metal of cooking pots conducts heat well to cook food and boil water, the metals that make up some heaters also need to conduct heat well. Coefficient of Volume Thermal Expansion Refractoriness They can do it either here in the workbook or in a separate notebook if you make use of these. What do we call the temperature at which the ice melts? It denoted by “αA”. She places the unknown liquid in a beaker and carefully heats it on a hot plate. Theoretically it is equal to the melting point. Evaporation can take place at any temperature. Flexible means supple and bendy; able to flex and bend. Add marbles one-by-one to the yoghurt tub until the paper tears. (b) Physical properties (density, specific heat, melting and boiling point, thermal expansion and conductivity, electrical and magnetic properties) To finalize the material for an engineering product or application, we should have the knowledge of physical properties of materials. The temperature at which water boils is called the boiling point of water. The elastic modulus of the material affects how much it deflects under a load, and the strength of the material determines the stresses that it can withstand before it fails. Do they think it looks great? You could add that it could be insured against theft, but that insurance on a car this valuable would be very expensive. However, practically there may be observed some difference. How did the temperature of the water change over time? Let's make some predictions. Place the boiling and melting points of the substances listed below on the blank template provided and then answer the questions. 4. What are the disadvantages of a car made of gold? Chemical properties are discovered by observing chemical reactions. Some of the liquid water turned into gas, that is why there were bubbles. What state would nitrogen be in at room temperature? We always have to weigh up the advantages against the disadvantages when we choose materials for a particular job. Physical Properties. Plantations take up a lot of space and therefore natural, indigenous vegetation has to be cleared (deforestation). Can you think of at least three different ways to boil water? Mechanical properties are how the metal performs when different forces are applied to them. planning investigation, doing investigation, recording information, comparing, communicating. The boiling point of water also depends on the purity of the water. The size and shape of a raw food material can vary widely. Now look carefully at the torn edge. Remember that the, The dependent variable should be 'Temperature'. Discuss this with your class and write your answer down. Investigation: Which type of paper is the strongest? It would probably also scratch easily. Suppose you mix some water and some ethanol. How would you modify the investigation to test the flexibility of different types of materials? Boiling point is the temperature at which a liquid boils. Although this is hugely beneficial for the economy, it has devastating effects on the environment. The physical properties of a material are those which can be observed without any change of the identity of material. We used paper strips of the same length and width. The water will boil in a shorter time. When water is boiled over a bigger flame, it will boil at a higher temperature. Its unit in SI system is watts per meter per K. It is the property of materials which represents that how easily the electricity can be conducted by the material. Have a look at the table that you filled in for part 1 to give you some hints. Use the space provided to draw your own table to record your results. When a material is in melting condition, it contains some dissolved gases within the material. This property of materials is called plasticity. Encourage them to take notes: What would happen if you tried to put the kettle into the microwave or on the stove? Any given material will melt and freeze at the same temperature. Place the beaker in a warm spot (you could even heat it carefully over the Bunsen burner). You can explain this to your learners after you have done this question. Electrical4U is dedicated to the teaching and sharing of all things related to electrical and electronics engineering. We punched the hole in exactly the same place on all the strips. Evaporation can take place below the boiling point of a liquid, but boiling takes place only once the liquid is heated and reaches its boiling point. When the temperature gets to a certain point (called its melting point), the wax starts to melt as it changes state from a solid to a liquid. Specific Gravity of Materials. In order for water to boil it needs to be heated. Since we have to make temperature measurements in the investigation, we are going to first check if everyone knows how temperature is measured. Make sure to use a range of papers, such as filter paper, tissue paper, crepe paper, wax paper, newspaper, normal white paper, harder card, etc. 1.1 Physical properties of materials (5 hours), Activity: Thinking about materials and their properties, Accessing and recalling information, classifying and sorting, Activity: Advantages versus disadvantages, Accessing and recalling information, comparing, identifying problems and issues, writing. This is called the normal boiling point of water. What do you think causes one paper to be stronger than another? Once all the ice has melted, continue to measure the temperature every 3 minutes, 3 more times. Note: Once all the ice has melted, the temperature of the water begins to rise. An interesting video on a new type of 'concrete canvas' with varying properties. Which of the above properties would be important if you were choosing a material for making cookware (cooking pots)? It is denoted by “ρ”. composites (made from two or more materials combined together) Different materials have different features, or properties, which make them suitable for different uses. Boiling point-It is the temperature (in oC or K) at which the substance changes from liquid state to gaseous state. Then the Density of material. Make sure that the holes are in the middle, and also at the same distance from the end of each strip. What does it mean when a material is flexible? 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