Name Matter and Change: Unit Objective Study Guide Date Due Directions: Write your answers to the following questions in the space provided. For problem solving, all of the work leading up to the final answer must be shown in order to receive credit. No credit will be given for magic answers. 1. Define chemistry and give examples of everyday uses of chemistry. Chemistry the study of the structure, properties, and composition of matter, and the changes that matter undergoes. Examples of Uses of Chemistry in Everyday Life Eating, Driving a car, Baking, etc. 2. List and describe the six branches of chemistry. a. b. c. d. e. f. 1
3. Describe the importance of models and give some examples. What is a model? A model is a visual, verbal, and/or mathematical explanation of experimental data. What can models be used for? Give some examples of models. Model of the atom, computer model of a storm 4. Differentiate between observations and inferences. What is an observation? How are observations made? An observation is information obtained through your five senses. Example: The lights are off in the house. What is an inference? An inference is a possible explanation based upon observations and previous knowledge. Example: Since you notice that the lights are off in the house, you infer that no one is home. 5. Differentiate between qualitative and quantitative observations and give an example of each. Qualitative factual descriptions that do not use numbers Example: The candle is long and skinny. Quantitative factual descriptions that do use numbers Example: The candle is 12 long. 2
6. List and describe the typical steps of the scientific method. a. Ask a question. b. Gather information. c. Formulate a hypothesis d. Conduct an experiment e. Record and analyze data f. Report Results 7. Define matter, mass, volume, and weight. Matter anything that has mass and volume (takes up space) Mass the amount of matter in an object Volume the amount of space an object takes up Weight the response of mass to the pull of gravity 3
8. Differentiate between mass and weight. If an astronaut went to a different planet would the mass of the astronaut change? Explain your answer. The mass of the astronaut would not change because the mass of an object is dependent upon the amount of matter in the object. The mass of an object is not affected by gravity. Would the astronaut s weight change? Explain your answer. The astronaut s weight would change. Weight changes with changes in gravity. If the gravitational pull on the other planet were greater, the astronaut would weigh more. If the gravitational pull on the other planet were smaller, the astronaut would weigh less. 9. Describe the three most common phases (states) of matter and the characteristics of each. Draw pictures representing the arrangement of particles in the three phases of matter. solid liquid gas Complete the following table. State Fluid Compressible Rigid Definite Shape Definite Volume solid no no yes yes yes liquid yes no no no yes gas yes yes no no no 4
10. Define viscosity and describe the factors that affect it. Viscosity the resistance of a fluid to flow Describe how each of the following affects the viscosity of a liquid. a. temperature As a l iquid gets warmer, its viscosity b. shape and size of molecule large, bumpy molecules create c. intermolecular forces of attraction the stronger the attractive forces between the molecules, the harder it is for the molecules to slide past one another. The stronger the intermolecular forces of attraction, the greater the v iscosity. 5
11. Define density and describe the factors that affect it. Density the ratio of the mass of an object to its volume What is the formula for calculating density? Why must the temperature be given when stating the density of a substance? Generally, as the temperature of a substance increases, the density decreases. This is because the molecules move farther apart from each other causing the volume to increase without changing the mass. Does the density of a substance depend upon the amount of the substance you have? Explain your answer. The density of a substance is an intensive physical property and does not depend upon the amount of the substance you have. For example, if you cut a block of wood in half, the mass and volume will both change proportionally. 6
12. Experimentally determine the density of different solids or liquids. Describe how you would find the density of each of the following in the laboratory. a. small rock First determine the mass of the small rock on a balance. Next determine the volume of the rock by water displacement. Half fill a 100 ml graduated cylinder with water and record the volume. Carefully place the rock in the water. Record the new volume. The volume of the rock is the difference between the final volume and the original volume. Divide the mass of the rock by the volume of the rock to find the density. b. rectangular piece of aluminum First determine the mass of the piece of aluminum on a balance. Next use a ruler to measure the length, width, and height of the piece of aluminum. Multiply the length, width, and height to find the volume. Divide the mass of the aluminum by the volume of the aluminum to find the density. c. vegetable oil First measure the mass of an empty 10 ml graduated cylinder. Add some vegetable oil to the graduated cylinder. Record the volume. Measure the mass of the graduated cylinder with the vegetable oil in it. The mass of the vegetable oil is the difference between the mass of the graduated cylinder with the vegetable oil in it and the mass of the empty graduated cylinder. Divide the mass of the vegetable oil by the volume of the vegetable oil to find the density. 7
13. Use the formula D=m/V to calculate any of the missing variables. a. Calculate the density of an object with a mass of 90.0 g and a volume of 65.0 cm 3. Would the object float in water? Explain your answer. 90.0 g D = m V = 65.0 cm 3 = 1.38 g/cm3 The object would not float in water because it has a higher density than water. (The density of water = 1.0 g/cm 3.) b. A sample of a liquid has a mass of 9.0 g and a density of 1.20 g/ml. What volume does the liquid occupy? V = m D = 9.0 g 1.20 g/ml = 7.5 g/ml c. A metal object has a density of 2.70 g/cm 3. The object has the following dimensions 4.0 cm 2.0 cm 2.0 cm. What is the mass of the object? 14. Differentiate between physical properties and chemical properties and give examples of each. Physical Property A physical property of a substance is a property which can be observed or measured without changing the substance s chemical composition. Examples: mass, volume, density, color, melting point Chemical Property A chemical property of a substance describes the ability of a substance to undergo chemical reactions and form new substances. Examples: flammability, reactivity to air, reactivity to acid 8
15. Classify physical properties as intensive or extensive. Intensive A physical property that remains the same no atter how much of a substance is present Examples: density, color, melting point Extensive A physical property that is dependent upon the am ount of substance present. Examples: mass, volume, length 16. Differentiate between chemical changes and physical changes and give examples of each. Physical Change A type of change that alters the physical properties of a substance but does not change its chemical composition. Examples: folding a piece of paper, dissolving salt in water, melting ice Chemical Change A type of change that results in the production of a new (different) substance with different physical and chemical properties. Examples: burning paper, reacting a metal with acid, oxidat ion of iron (rusting) 9
17. List four indications that a chemical change (chemical reaction) has occurred. a. Chang e in color or odor b. Ch ange in energy (endothermic or exothermic). c. Production of a gas (bubbling). d. Format ion of a precipitate. 18. Define reactant(s) and product(s). Identify the reactant(s) and product(s) of a chemical reaction. Reactant(s) starting substances in a chemical reaction. Theactants are written on the left side of the arrow. Product(s) substances produced by a chemical reaction. The roducts are written on the right side of the arrow. Write an example of a chemical reaction and identify the reactant(s) and product(s). 2NaCl(s) 2Na(s) + Cl 2 (g) Reactant: NaCl Prod 10
19. State the Law of Conservation of Mass and use it to determine the mass or a reactant or product involved in a reaction. Law of Conservation of Mass Mass can be neither created nor destroyed in an ordinary chemical or physicalprocess. 23.00 g of sodium metal reacts with 70.90 g of chlorine gas to produce sodium chloride. What mass of sodium chloride is produced? Mass of reactants = mass of product 23.00 g + 70.90 g = 93.90 g A student conducted an experiment in the lab in which he reacted baking soda with vinegar. When the student measured the mass of the products, he found that the product mass was less than the reactant mass. Give an explanation for his results. The student produced a gas. The gas was not captured and its mass was not included when determining the mass of the products. 20. Define energy and give examples of different forms of energy. Energy the capacity for doing work Examples: chemical, nuclear, electrical, radiant, mechanical, thermal, solar 21. Differentiate between kinetic energy and potential energy. Kinetic energy the energy an object has due to its motion What factors affect kinetic energy? mass, velocity Potential energy the energy an object has due to its position or composition What factors affect potential energy?he ground, chemical composition 11
22. State the Law of Conservation of Energy and give an example of how this would apply to a chemical reaction. Law of Conservation of Energy in any chemical or physical process, energy may change from one form to another, but it is neither created nor destroyed. A chemical reaction releases energy in the form of heat and light. Where did the energy released come from? The energy released was originally stored in the chemical bonds of the reactants. 23. Distinguish between endothermic and exothermic reactions and draw reaction diagrams for both. Endothermic reaction A chemical reaction in which a greater amount of energy is required to break the existing bonds in the reactants than is released when the new bonds form in the product molecules. Exothermic reaction A chemical reaction in which more energy is released than is required to break bonds in the initi al reaction Reaction Diagram - Endothermic Reaction Reaction Diagram - Exothermic Reaction 12
24. Identify reactions as endothermic or exothermic. Classify each of the following as endothermic or exothermic. a. CH 4 + 2O 2 CO 2 + 2H 2 O + energy Exothermic b. A test tube containing a white solid is heated and the white solid decomposes. Endothermic c. A student adds sodium bicarbonate to a test tube containing hydrochloric acid. When the student touches the test tube she notices that it is cold. Endothermic 25. Differentiate between elements, compounds, and mixtures. Consider the following when differentiating between them: Composition, Properties, Method used to separate components, homogeneous or heterogeneous. Element a pure substance made of only one type of atom that cannot be broken down into simpler substances by physical or chemical means. Elements are homeneous. Compound a pure substance which is a chemical comination of two or more different types of elements. A compound can be broken down into simpler subby chemical means and has properties different from those Mixture a physical combination of two or more pure substances in any proportions in which each of the substances retains its individual properties; can be Mixtures have a variable composition and compounds have a definite composition. Explain what this means. be combined in different ratios. For example, two different glasses of salt water could contain different amounts of salt or water. 13
26. Classify substances or mixtures as homogeneous or heterogeneous. 27. Classify things as elements, compounds, or mixtures. Define homogeneous matter that has the same composition throughout Define heterogeneous matter that does not have the same composition throughout What is a pure substance? Are pure substances homogeneous or heterogeneous? A pure substance is a sample of matter, either an element or a compound, that consist of only one and a definite composition. Pure substances are homogeneous. What is a mixture? Are mixtures homogeneous or heterogeneous? A mixture is a physical combination of two or more substances that can be separated by physical means. A mixture can be homogeneous (solution) or Classify each of the following as a pure substance or a mixture. Then classify them as homogeneous or heterogeneous. Give a reason for your answer. a. iron filings pure substance, homogeneous, iron is an element b. table salt pure substance, homogeneous, sodium chloride is a compound c. air mixture, homogeneous, air is a mixture of different gases d. vinegar and oil dressing mixture, heterogeneous, vinegar and oil settle 14
28. Use a period table to name elements, given their symbols. 29. Use the periodic table to write the symbols of elements, given their names. Complete the following table. Name Symbol Name Symbol Carbon C Lead Pb Helium He Sodium Na Oxygen O Potassium K 30. Describe the arrangement of the periodic table. number The elements are arranged in order of increasing atomic. Elements within the same have similar chemical properties. Group or Family vertical column in the periodic table How are the Groups or Families labeled on the periodic table? How many are there? They are labeled 1-18 or 1A, 2A, etc at the top of the group. There are 18 groups Period horizontal row in the periodic table How are the Periods labeled on the periodic table? How many are there? They are labeled 1-7 at the left of the period. There are 7 periods. Location of Metals: Left side of periodic table Examples of Metals: Silver, Sodium, Mercury, Gold, Copper, Magnesium Location of Nonmetals: Right side of periodic table ( Examples of Nonmetals: Hydrogen, helium, nitrogen, sulfur, carbon, fluorine Location of Metalloids: Between the metals and nonmetals -p Examples of Metalloids: Boron, Silicon, Antimony, Tellurium, Germanium, Arsenic 15
31. List the characteristics that distinguish metals, nonmetals, and metalloids. Complete the following table. malleable/ductile brittle metal yes no nonmetal metalloid no some are/some aren t Conductor of heat and electricity Solid, Liquid or Gas at room temperature good Mostly Solids conductor (Hg is a liquid) poor solids, liquids conductor or gases yes semiconductor all are solids some are/some aren t 16