Chapter 1 â Section 2 Describing Matter
ame __________________________ Period _______
Chapter 1 – Section 2 Describing Matter
Physical property: Density: Chemical property: Physical Change: Chemical Change:
Lesson 2: Physical and Chemical Properties When you come into a new situation or have to make any kind of decision, what do you usually do first? Most people would make some observations. In the laboratory, you use your senses and scientific instruments to make observations all the time. Any cha characteristic racteristic of a material that can be observed or measured without changing the identity of the material is a physical property. Remember – never taste, touch or sell any of the materials being used in the lab unless you are instructed to do so. You rely on physical properties all the time. For example, physical properties help you determine whether your socks are clean (odor), whether you can fit all your books in your backpack (volume), or whether your shirt matc matches hes your pants (color). Review the table tabl on page 12 of your book to review more physical properties useful in describing or identifying matter. Length and Mass Some properties of matter can be identified by using your senses, and other properties can be measured. How much is there? How much space does it take up? One useful and measurable property is length. Length is measured using a ruler, meter stick, tape measure, or some other measuring device. Objects could be classified by their length as in the photo below.
sical property that can be used to classify objects. You should remember Mass is another physical from our previous lesson that mass describes the amount of material in an object. Volume and Density Mass isn’t the only physical property that describes how much of something you have. Another measurement is volume. Volume measures the amount of space an object takes up. Liquids are usually easured by volume. Density is another measurable physical property related to mass and volume. Denisty is the amount of material in a given volume. You notice this property when you try to lift two things of equal volume that have different masses. The formula for determining density is the mass of the object divided by its volume. Density = mass/volume, or D = m/V
Remember that I LOVE Density…..
Calculating Mass, Volume or Density with the Triangle Method - The vertical line in the triangle means multiply. - The horizontal line in the triangle means divide. If two of the values of D (density) , V (volume) or M (mass) are known, then you can work out the other using one of the following:
V = M/D D = M/V M=DxV Sample Problems: 1. What is the density of a block of aluminum with a volume of 30.0 cm3 and a mass of 81.0 grams?
D= M/V 81
30
?
2. A student determines that a piece of an unknown material has a mass of 5.854 g and a volume of 7.57 cm3. What is the density of the material?
D= M/V
5.854
?
7.57
3. What is the mass of an iron horseshoe with a volume of 89 cm3? The density of iron is 7.9 g/cm3.
M=DxV
? 7.9
89
4. What is the volume of a 525-gram block of lead? The density of lead is 11.3 g/cm3.
V = M/D 525
11.3
?
Practice problems - show your work for credit! 1. A solid rubber stopper has a mass of 33.0 grams and a volume of 30.0 cm3. What is the density of rubber?
2. A chunk of paraffin (wax) has a mass of 50.4 grams and a volume of 57.9 cm3. What is the density of paraffin?
3. A marble statue has a mass of 6,200 grams and a volume of 2,296 cm3. What is the density of marble?
4. The density of cork is 0.24 g/cm3. What is the volume of a 240gram piece of cork?
5. The density of gold is 19.3 g/cm3. What is the volume of a 575gram bar of pure gold?
6. The density of mercury is 13.6 g/mL. What is the volume of a 155-gram sample of mercury?
7. What is the density of a piece of wood that has a mass of 25.0 grams and a volume of 29.4 cm3?
Why is density useful in identifying substances? #1 – The density of a particular substance is always the same at a given pressure and temperature. #2 – The density of one substance is usually different than that of another substance.
The table below shows the density of some common substances
Look at figure 12 on page 14 of your text. What do you think causes the liquid in the jar to look that way? There are actually FOUR different liquids in the jar Each liquid has a different density, because of this they separate into layers instead of mixing together. This is like the lab activity that we performed in class. _______________________________________ _______________________________________ _______________________________________ _______________________________________ _______________________________________ _______________________________________ ______________________________________ ______________________________________________________________________________ ______________________________________________________________________________
Physical properties are not the only properties that describe matter. Chemical properties describe a substance based on its ability to change into a new substance with different properties. Examples of some chemical properties
Chemical properties can be observed with your senses, however they are not as easy to observe as physical properties. For example, you can observe the flammability of wood only while the wood is burning. A substance always has its chemical properties even if you are not directly observing it. A piece of wood is still flammable even when it is not burning.
Physical vs. Chemical Properties You can describe matter by both physical and chemical properties. The properties that are most useful in identifying a substance such as density, solubility, and reactivity with acids are its characteristic properties. The characteristic properties of a substance are always the same whether the sample you are observing large or small. Scientists rely on characteristic properties to identify and classify substances. It is important to remember the differences between physical and chemical properties. Classifying according to physical properties is often easier than classifying according to chemical properties. This is because the physical properties of a substance are easily observed, but the chemical properties cannot be observed without changing the substance.
Physical Properties
Chemical Properties
Color, shape, length, mass, volume, density, state of matter, magnetism, melting point, boiling point, malleability, ductility
Flammability, reacts with oxygen, water, vinegar, etc…reacts in the presence of light, heat, etc…
Complete the following table comparing properties of different objects. Properties of Matter Type of Matter Log Pillow Bowl of Cookie Dough Book Glass of Orange Juice
Physical Properties
Chemical Properties
Lesson 3: Physical and Chemical Changes A physical change is a change that affects one or more physical properties of a substance. As an example, if you break a piece of chalk in two, you change its physical properties of size and shape but it still remains chalk. The chalk is still chalk. During a physical change, a substance does not become a different substance.
Examples of Physical Changes
Because physical changes do not change the identity of substances, they are often easy to undo. A chemical change occurs when one or more substances are changed into entirely new substances with different properties. How do you know that you have a new substance? Look at the piece of birthday cake below: When you bake a cake, you combine eggs, flour, sugar butter, and other ingredients. Each ingredient has its own set of properties. But if you mix them together and bake the batter in the oven, you get something completely different. When a cake bakes, gas bubbles form and grow within the ingredients Bubbles are a sign that a chemical change has taken place. When you look closely at a piece of cake, you can see the air holes left by the bubbles. Others signs of change include the production of light, heat, smoke, changes in color and sound. Chemical changes CANNOT be reversed using physical means.
Chapter 1 – Section 2 Describing Matter
Physical property: Density: Chemical property: Physical Change: Chemical Change:
Lesson 2: Physical and Chemical Properties When you come into a new situation or have to make any kind of decision, what do you usually do first? Most people would make some observations. In the laboratory, you use your senses and scientific instruments to make observations all the time. Any cha characteristic racteristic of a material that can be observed or measured without changing the identity of the material is a physical property. Remember – never taste, touch or sell any of the materials being used in the lab unless you are instructed to do so. You rely on physical properties all the time. For example, physical properties help you determine whether your socks are clean (odor), whether you can fit all your books in your backpack (volume), or whether your shirt matc matches hes your pants (color). Review the table tabl on page 12 of your book to review more physical properties useful in describing or identifying matter. Length and Mass Some properties of matter can be identified by using your senses, and other properties can be measured. How much is there? How much space does it take up? One useful and measurable property is length. Length is measured using a ruler, meter stick, tape measure, or some other measuring device. Objects could be classified by their length as in the photo below.
sical property that can be used to classify objects. You should remember Mass is another physical from our previous lesson that mass describes the amount of material in an object. Volume and Density Mass isn’t the only physical property that describes how much of something you have. Another measurement is volume. Volume measures the amount of space an object takes up. Liquids are usually easured by volume. Density is another measurable physical property related to mass and volume. Denisty is the amount of material in a given volume. You notice this property when you try to lift two things of equal volume that have different masses. The formula for determining density is the mass of the object divided by its volume. Density = mass/volume, or D = m/V
Remember that I LOVE Density…..
Calculating Mass, Volume or Density with the Triangle Method - The vertical line in the triangle means multiply. - The horizontal line in the triangle means divide. If two of the values of D (density) , V (volume) or M (mass) are known, then you can work out the other using one of the following:
V = M/D D = M/V M=DxV Sample Problems: 1. What is the density of a block of aluminum with a volume of 30.0 cm3 and a mass of 81.0 grams?
D= M/V 81
30
?
2. A student determines that a piece of an unknown material has a mass of 5.854 g and a volume of 7.57 cm3. What is the density of the material?
D= M/V
5.854
?
7.57
3. What is the mass of an iron horseshoe with a volume of 89 cm3? The density of iron is 7.9 g/cm3.
M=DxV
? 7.9
89
4. What is the volume of a 525-gram block of lead? The density of lead is 11.3 g/cm3.
V = M/D 525
11.3
?
Practice problems - show your work for credit! 1. A solid rubber stopper has a mass of 33.0 grams and a volume of 30.0 cm3. What is the density of rubber?
2. A chunk of paraffin (wax) has a mass of 50.4 grams and a volume of 57.9 cm3. What is the density of paraffin?
3. A marble statue has a mass of 6,200 grams and a volume of 2,296 cm3. What is the density of marble?
4. The density of cork is 0.24 g/cm3. What is the volume of a 240gram piece of cork?
5. The density of gold is 19.3 g/cm3. What is the volume of a 575gram bar of pure gold?
6. The density of mercury is 13.6 g/mL. What is the volume of a 155-gram sample of mercury?
7. What is the density of a piece of wood that has a mass of 25.0 grams and a volume of 29.4 cm3?
Why is density useful in identifying substances? #1 – The density of a particular substance is always the same at a given pressure and temperature. #2 – The density of one substance is usually different than that of another substance.
The table below shows the density of some common substances
Look at figure 12 on page 14 of your text. What do you think causes the liquid in the jar to look that way? There are actually FOUR different liquids in the jar Each liquid has a different density, because of this they separate into layers instead of mixing together. This is like the lab activity that we performed in class. _______________________________________ _______________________________________ _______________________________________ _______________________________________ _______________________________________ _______________________________________ ______________________________________ ______________________________________________________________________________ ______________________________________________________________________________
Physical properties are not the only properties that describe matter. Chemical properties describe a substance based on its ability to change into a new substance with different properties. Examples of some chemical properties
Chemical properties can be observed with your senses, however they are not as easy to observe as physical properties. For example, you can observe the flammability of wood only while the wood is burning. A substance always has its chemical properties even if you are not directly observing it. A piece of wood is still flammable even when it is not burning.
Physical vs. Chemical Properties You can describe matter by both physical and chemical properties. The properties that are most useful in identifying a substance such as density, solubility, and reactivity with acids are its characteristic properties. The characteristic properties of a substance are always the same whether the sample you are observing large or small. Scientists rely on characteristic properties to identify and classify substances. It is important to remember the differences between physical and chemical properties. Classifying according to physical properties is often easier than classifying according to chemical properties. This is because the physical properties of a substance are easily observed, but the chemical properties cannot be observed without changing the substance.
Physical Properties
Chemical Properties
Color, shape, length, mass, volume, density, state of matter, magnetism, melting point, boiling point, malleability, ductility
Flammability, reacts with oxygen, water, vinegar, etc…reacts in the presence of light, heat, etc…
Complete the following table comparing properties of different objects. Properties of Matter Type of Matter Log Pillow Bowl of Cookie Dough Book Glass of Orange Juice
Physical Properties
Chemical Properties
Lesson 3: Physical and Chemical Changes A physical change is a change that affects one or more physical properties of a substance. As an example, if you break a piece of chalk in two, you change its physical properties of size and shape but it still remains chalk. The chalk is still chalk. During a physical change, a substance does not become a different substance.
Examples of Physical Changes
Because physical changes do not change the identity of substances, they are often easy to undo. A chemical change occurs when one or more substances are changed into entirely new substances with different properties. How do you know that you have a new substance? Look at the piece of birthday cake below: When you bake a cake, you combine eggs, flour, sugar butter, and other ingredients. Each ingredient has its own set of properties. But if you mix them together and bake the batter in the oven, you get something completely different. When a cake bakes, gas bubbles form and grow within the ingredients Bubbles are a sign that a chemical change has taken place. When you look closely at a piece of cake, you can see the air holes left by the bubbles. Others signs of change include the production of light, heat, smoke, changes in color and sound. Chemical changes CANNOT be reversed using physical means.
