Teacher Slide Have oil, corn syrup, and water to demonstrate different viscosities. Have burner turned on low. Heat oil & corn syrup so that you can show how viscosity changes with temperature. Clay and crackers to illustrate malleability v. brittle.

Bell work 9/9/09 Q: Fill out this concept map and define the terms in the bottom three circles: Mixtures Homogeneous Heterogeneous

Section 2: Properties of Matter Objectives List examples of physical properties Understand the usefulness of knowing physical properties Identify processes to separate mixtures Identify when physical changes occur

Vocabulary Physical property Viscosity Conductivity Malleability Melting point Boiling point Filtration Distillation Physical change

Examples of Physical Properties We learned to characterize matter based upon uniformity of composition. We’ll now learn to categorize matter based upon its physical properties. Physical Property: any characteristic of a material that can be observed without changing the composition of the substance

Examples of Physical Properties Substances all around can be identified by many features. They can be categorized by these features such as their color, taste, how they feel, their temperature These are basic examples of physical properties that can be observed or measured. There are many more examples which this section will cover.

Why Does it Matter? If you were given a sample of water how could you determine if it was pure or not? By taste? Let’s say it’s salty. Salt isn’t going to kill you but what if there were a tasteless, colorless, odorless poison, such as Botulinum toxin, in the sample. You wouldn’t want to taste the sample then would you? The point is that water, salt, and toxins all have physical properties, that if known, can help you determine what substance is what.

Examples of Physical Properties Some of the more relevant physical properties in chemistry are: Viscosity Conductivity Malleability Hardness Melting and boiling points And density But there are others. This section is dedicated to surveying the physical properties of matter.

Examples of Physical Properties Viscosity: the tendency of a liquid to keep from flowing… to resist flowing. Take for instance, bottles of honey (or syrup) and vinegar. Which flows faster? If you were to pour out these bottles the vinegar would flow out much faster than the honey. Viscosity describes how a fluid flows, more specifically how slow it flows compared to another fluid.

Viscosity How do you describe viscosity? As with most physical properties, the method is based upon the comparison between different samples. The one that flows slower has higher viscosity.

Viscosity Consider driving in Arizona compared to driving in Minnesota. You would want to choose you motor oil depending on the temperatures outside. Too viscous and the oil may not flow in cold temps. Too thin and engine damage could occur.

Viscosity Viscosity can be important considering many substances, such as oil. Its resistance to flowing helps lubricate engine parts. Viscosity can change with temperature. So if you hear up oil it pours faster.

Viscosity v. Temperature Examine the graph and tell me how does viscosity change with temperature?

Examples of Physical Properties Conductivity: the ability to allow heat to flow Materials are categorized by conductivity for many important reasons. These come into play in everyday life and in industry as well Conductors have high conductivity They allow heat, and usually electricity, to flow very rapidly. Insulators generally have poor conductivity For example wood. Electricity and heat flow very slowly if at all throw the material. Glass is also another insulator. Inert gasses (such as argon) are others.

Materials for windows are chosen to reduce conductivity of heat between the inside and outside of homes. The glass has low conductivity. The “GAS FILL” is a noble gas, something like argon, which does not conduct heat.

Conductivity When you cook what type of utensil do you use? What happens when you use a metal spoon? If conductivity is the ability of heat to flow what material is the most conductive? A wooden spoon? A metal spoon? A plastic (nylon) spoon?

Examples of Physical Properties Malleability: the ability to be hammered or pressed without shattering. Materials that are malleable: Metal Clay Wax

Malleability Clay and wax are chosen for molds and sculptures because they can be shaped without them crumbling or shattering.

Other Examples of Physical Properties Ductility: The ability to be permanently deformed; such as bent, stretched, warped, or drawn into wires. A lot like malleability. Usually metals, like copper, gold, zinc, steel. The opposite of malleable & ductility is brittle. Glass Wood Crackers

Examples of Physical Properties Hardness is a relative description based upon observing which material can scratch the other. Hardness is usually used as a comparison between two materials. Such as diamonds are harder than glass.

Hardness Tools for wood carving are chosen because they are harder than wood.

Other Examples of Physical Properties Luster: a sheen or soft glow generated from a reflective surface. Luster is often discovered when a material is polished. Luster can come in a lot of forms. The opposite would be matte or dull.

Examples of Physical Properties Phase Changes When a substance changes its state it is a physical property of the substance. Example: When water boils some of the water molecules turn to a gas that rises to the top. Example: When dry ice (solid carbon dioxide) changes to a gas it still remains carbon dioxide…it’s just the gas version. When a substance changes state is an important physical property.

Examples of Physical Properties Melting point: the temperature at which a substance changes from a solid to a liquid Water “melts” from ice to water at around 33°F or 1°C Boiling point: the temperature at which a substance boils, or changes from a liquid to a gas Water boils at 212°F or 100°C

Examples of Physical Properties Melting and boiling points (pg 47) What do you notice about the units being used?

Quick Check Point. 1 minutes… Building Vocabulary Physical Property Definition Viscosity Malleability Melting Point Conductivity Luster The temperature at which a substance changes from a solid to liquid. the ability to allow heat to flow The tendency of a liquid to resist flowing The ability of a solid to be hammered without shattering a sheen or soft glow generated from a reflective surface.

Examples of Physical Properties Density: Ratio of the mass of a substance to its volume It can be a valuable test to check for a substance purity or useful physical property for choosing a substance for a particular job. Precious metals, fuels, chemicals are all examples of substances that are checked for purity by calculating their densities. What is the equation for calculating density? Density = mass/volume

Using Physical Properties Physical properties are used for several purposes: To identify a material To choose a material for a specific purpose To separate substances in a mixture

Using physical properties Using properties to ID materials This can lead to discoveries of unknowns The process: First identify the properties to test. Do you want to calculate density, melting point, boiling point, conductivity? Next test the sample. Then compare the findings with known materials. Use what’s already known to compare with your sample.

Melting and Boiling Points Melting and boiling points are used all the time for very important reasons. These physical properties allow substances to be separated by boiling point are to be chosen for particular uses. Such as adding salt to water in increase the boiling point, which speeds up cooking times. Such as metals are chosen to cook with because they conduct heat, but have very high melting points.

Density Densities for all pure substances are known and can be found searching the internet. If you have an unknown sample, how do you think that being able to calculate density could help determine it’s purity? If something has impurities it would have variable mass and different densities.

Using physical properties Using properties to choose materials The properties of a substance determine which materials are used in specific ways Choosing between materials based on their properties ensures effective products

Using physical properties Read and annotate physical properties on the hand out given. Discuss these questions with your group. What are some physical properties of clay? Of the metal? Of the wax? Which is more malleable? What are the different melting points (which is highest/lowest)? Describe this process for making a sculpture? Why is it important that wax has a lower melting point than clay?

Using properties to separate mixtures The physical properties of a substance can be used for a variety of reasons, one being deciding what to use for a specific task. Another use for knowing physical properties is purification, or isolating one specific substance from a mixture. Two methods of separating substances from one another based upon physical properties are: By filtration And by distillation

Using properties to separate mixtures Filtration: Is the process that separates materials based upon the size of their particles Filters are chosen depending on the materials that are wanted OUT of the mixture Range from strainers and sifts to filter paper and substances even more fine Filters can be physical (such as a collander or coffee filter) or chemical (such as in DNA purification).

Choose the best filter for the job. If you need to drain water from spaghetti. If you want to filter the flavor out of ground coffee beans. If you want to find bones in dirt.

Using properties to separate mixtures Distillation: The process that separates substances in a solution based upon their boiling points. Every substance has a unique boiling point. With this fact, mixtures can be heated to boil out substances in solution. Ex: purification of sea water.

Sea water in Purified water out

How Can This Help You? Imagine you are stranded without drinking water. What scientific technique could you use to purify a water source? Distillation Solar Still

Recognizing physical change Physical change: occurs when some of the properties of a material change, but the composition of substances in the material remain the same Some ways can be reversed Such as melting and freezing Example: Regardless of its state, either as ice or liquid or gas, water is always hydrogen and oxygen Some can’t Like cutting and slicing Example: Getting your hair cut.

Summary Physical properties include viscosity, conductivity, malleability, hardness, melting and boiling points, and density Knowing physical properties allow us to identify a material, to choose a material for a specific purpose, and to separate substances in a mixture Processes to separate mixtures include filtration and distillation Physical changes occurs when some of the properties of the material change but the substances remain the same.

Study Hint: Physical Properties Cluster 1 2 3 4 5 6 7 8 Name 8 physical properties and describe the features of this property in the correct box. Choose an example that demonstrates this property.

Comparing Viscosities 11 Observe these samples. Which of these samples has higher viscosity? Material High/Medium/Low Cooking Oil Corn syrup Water