Regents Chemistry Unit 1- Describing Matter Study Guide & Pre-Test KEY

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1 Regents Chemistry Unit 1- Describing Matter Study Guide & Pre-Test KEY Focus Questions for the Unit: How is matter organized and classified? What are the types of matter? How can we distinguish one type of matter from another? How do chemists represent matter using symbols and drawings? How are measurements made, used, and analyzed in chemistry? How can matter be changed? How to use the pre-test: This should be your way to monitor your understanding of the unit. For most people, I would suggest that first you look through the vocabulary for the unit, your unit packet (assignments and labs), and old quizzes to see if there is anything that you still don t understand. Try to figure this out! Then, use the pre-test like it was the actual test (do it without any help). Check your answers and then use your resources (the answer key, the packet, friends, or your teacher) to help you figure out what you still don t understand. The questions are listed by Topics, which will help you know where to look for more info if you get it wrong. If you struggle a lot the first time you take the pre-test, you may want to consider printing off a second, blank copy of the pre-test and trying it again after you have studied to make sure you truly have learned the material and can do it by yourself. Think about it... if you do this immediately after you finish going over the pre-test the first time, it is not a good tool because you are only testing if you can memorize the answers, not if you can apply what you have learned. As a result, you will over-estimate your abilities and not really be prepared for the test. This means that you will probably want to spread this out over two days. Basically, don t want to wait until the night before the test to start studying! Remember, there are no re-takes on tests. Old Quizzes I strongly suggest you study these. This does not mean passively look over them and try to memorize the answer. It does mean actively figure out why you got something wrong. You should decide if you didn t understand what the question was asking, or if you didn t understand the concept. These are two very different things and you should do different things to study depending on which it was. Your teacher can help you with this. Learning Styles You should have thought about some study strategy suggestions that work for you after completing the learning styles activity in class. They should be written in on page 7 of your unit packet. Review these and study accordingly. What You Should Know and Understand At the beginning of each Topic there is a list of the objectives/goals for each topic. Read through these and think about questions that you have seen that relate to each one. You can do this by looking back at your quizzes, as well as your warm-ups and tickets out. Labs: Your labs are in the packet and the keys are online. USE THEM!!! Also, don t forget that your lab abstracts summarize each lab that you did and are available to you to use to study if you would like them. Vocabulary: Use the next page to make sure you know the key words for the unit. This is especially important if you get things wrong because of not knowing what the question was asking... ask yourself if you ve ever said, I don t know what to do and then when I show you, you say that s it?! This is usually caused by a word in the question that you didn t know and it threw you off. If you know it, make sure you can show it! 1

2 Key Words to Know: (Check off the ones that you know and study the other ones!) Vocab Definitions/Related Words Topic 2: States and Properties of Matter matter physical property o mass o volume o density o hardness o state (phase) solid, liquid, gas chemical property qualitative quantitative Topic 3: Math of Chemistry 101 accuracy precision significant figures percent error direct relationship inverse relationship slope metric prefixes o centi-, milli-, kilo- Topic 4: Classification of Matter particle (atom) types of matter-pure substances o element o compound fixed ratio/composition Topic 5: Mixtures types of matter-mixtures o mixture homogeneous heterogeneous aqueous solution percent composition distillation filtration Topic 6: Pure Substances monatomic element/compound diatomic element/compound Topic 7: Changes physical change o phase change chemical change conservation of matter/energy exothermic endothermic Reference Tables Used: Tables A, C, S, T, & Periodic Table 2

3 Vocabulary Practice: Chemical change Coefficient Compound Diatomic element Element Endothermic Exothermic Gas Heterogeneous Homogeneous Matter Mixtures Percent composition Percent error Physical change Pure substances Qualitative Quantitative STP Subscript Matter 1. Anything that has mass and volume Percent composition 2. The composition of a compound of each element compared with the total mass of the compound Compound 3. Substance in which the atoms exist in a fixed ratio Chemical change 4. A reaction in which the composition of a substance is changed Diatomic element 5. An element containing two identical atoms Physical change 6. A change that does not alter the chemical properties of a substance Pure Substance 7. Type of matter that includes compounds and elements only Mixtures 8. Type of matter that includes homogeneous or heterogeneous substances Quantitative 9. Description of numerical information Qualitative 10. Description of non-numerical information Percent error 11. Actual error divided by the accepted value and multiplied by a factor of one hundred Subscript 12. The number that indicates the number of atoms present Coefficient 13. The number that indicates the number of units or molecules of that substance Endothermic 14. Process in which energy is absorbed Exothermic 15. Process in which energy is released Heterogeneous 16. Mixture in which the substances are not uniformly distributed Homogenous 17. Mixture in which the substances are uniformly distributed STP C, 273K, 1 atm, kpa Element 19. Form of matter which cannot be simplified or broken down any further by chemical means Gas 20. Phase of matter without definite shape or volume 3

4 Topic 2: States and Properties of Matter 1. Draw particle diagrams for a solid, a liquid, and a gas. ( at least 6 particles) Explain the differences between these states. Make sure to consider volume, density, energy, and attraction between particles. Solid (s) Liquid (l) Gas (g) Solids have a definite volume and a high density (due to the strong attraction between particles). Since the particles are tightly packed, they are not moving very much, and have low energy. Liquids have a definite volume (does not change no matter what container it is in). The particles are not as close together as a solid, so liquids are less dense and are only somewhat attracted to one another. They move more than a solid. Gases are spread out and take up the volume of any container they are in (not definite). Because of this they are not very dense and are moving a lot with a ton of energy. The particles are not attracted to one another. 2. The particles of a substance are arranged in a definite geometric pattern and are constantly vibrating. This substance can be in (1) the solid phase, only (3) either the solid or the liquid phase (2) the liquid phase, only (4) neither the liquid nor the solid phase 3. Use Table S to determine if these elements are in the solid, liquid, or gas state at STP. If the name is given, give the symbol, or vice versa. Symbol Name State S Sulfur Solid Na Sodium Solid Ne Neon Gas N Nitrogen Gas Mg Magnesium Solid 4. Iron is heated up to 2900 degrees Kelvin. Using the data on Table S, determine whether the iron is in the solid, liquid or gas state at this temperature. Explain how you know. Iron (Fe) is a liquid at 2900K because it has already surpassed (gone above) the melting point of 1808K, which means it has already melted (went from a solid to liquid), but it has not reached the boiling point of 3023K, so it has not boiled or turned into a gas. 4

5 Topic 3: The Math of Chemistry Do the following conversions: Significant figures (depends if you kept a decimal pt. after conversion) a ml = L 5 b kg = 52,600 g 5 with decimal pt. 3 w/o decimal point c g = 93,900 mg 5 with decimal pt. 3 w/o decimal point 2. Calculate the density of 67.2 ml of alcohol whose mass is 56.1 grams: mass D = volume 56.1 g D = = g/ml 67.2 ml 3. Density is a key property because it is so useful in identifying a substance. You determine the mass of a piece of aluminum to be 55.9 grams. a.) Calculate the volume of the piece of metal that you massed. Show all work and round to the appropriate decimal value. mass D = volume 55.9 g 2.70 g/cm 3 = volume 2.70 g/cm 3 (v) = 55.9 g volume= 20.7cm g/cm g/cm = 3 sig figs 2.70 = 3 sig figs the answer should contain 3 sig figs! b.) If you had 83.1 grams of aluminum, would the density increase, decrease, or remain the same? Explain. Density would stay the same as long as it is the same substance. Density is a ratio of mass/volume and it is a direct relationship; as mass increases the volume increases, so density stays constant. 5

6 Topic 4: Classification of Matter 1. Is an atom the same thing as an element? Why or why not? An atom is one single piece of matter. An element is always the same type of atom but can be made up of more than one of the atoms. Therefore they are not the same. 2. What are the chemical symbols of the following elements? a. bromine Br b. sodium Na c. potassium K d. hydrogen H 3. Draw a particle diagram showing 5 NO2 in the gas state. Include a key. N = O = NO2 = 4. Which statement describes the composition of potassium chlorate, KClO3? (1) The proportion by mass of elements combined in potassium chlorate is fixed. (2) The proportion by mass of elements combined in potassium chlorate varies. (3) Potassium chlorate is composed of four elements. (4) Potassium chlorate is composed of five elements. 5. Every water molecule has two hydrogen atoms bonded to one oxygen atom. This fact supports the concept that elements in a compound are (1) chemically combined in a fixed proportion (3) physically mixed in a fixed proportion (2) chemically combined in proportions that vary (4) physically mixed in proportions that vary 6. Which particle model diagram represents only one compound composed of elements X and Z? An unidentified sample is tested in a chemical laboratory. It is shown to contain the elements copper and iodine. Bart thinks the sample is a mixture of copper (Cu) and iodine (I2). Lisa thinks the sample contains the compound copper iodide (CuI). 6

7 7. Draw particle diagrams of at least 6 particles in each diagram, to represent both ideas. Use these symbols to construct the particles in your diagrams: Iodine = Copper = Lisa s idea Bart s idea (the compound CuI) (mixture of Cu and I2) 8. How many of each type of atom are given in the following compounds? (Draw them if it helps.) a.) Ba3(PO4)2 3 Ba atoms 2 P atoms 8 O atoms b.) 3 Ba3(PO4)2 9 Ba atoms 6 P atoms 24 O atoms 9. Explain the difference between CO2 and 2 CO. CO2 is one molecule containing one atom of Carbon (C) and two atoms of Oxygen (O). 2 CO is two molecules, each containing one atom of Carbon (C) and one atom of Oxygen (O). Topic 5: Mixtures 1. A compound differs from a mixture in that a compound always has a (1) homogeneous composition (3) minimum of three components (2) maximum of two components (4) heterogeneous composition 2. Which of these terms refers to matter that could be heterogeneous? (1) element (2) mixture (3) compound (4) solution 3. When sugar is dissolved in water and mixed well, the resulting solution is classified as a (1) homogeneous mixture (3) homogeneous compound (2) heterogeneous mixture (4) heterogeneous compound 4. Which is a characteristic of all mixtures? (1) They are homogeneous. (2) They are heterogeneous. (3) Their composition is a definite ratio. (4) Their composition can be varied. 5. Which is true of all mixtures? (1) They are homogeneous (2) They are heterogeneous (3) They are able to be separated into their components by physical change (4) They are able to be separated into their components by chemical change 7

8 6. Given: Which diagram represents a mixture? 7. Which formula represents a mixture? (1) C6H12O6(l) (2) C6H12O6(s) (3) LiCl(aq) (4) LiCl(s) a. Explain how you chose your answer. Aq indicates an aqueous soilution, which means that LiCl was dissolved in water. Dissolving is a physical change and it forms a mixture, not a compound. b. How would this mixture be classified? Homogeneous c. How would you separate this mixture back into its components? Boil off the water (H2O) leaving the LiCl behind. 8. Draw a particle diagram of a homogeneous mixture and a heterogeneous mixture of solid iron (Fe) and sulfur (S). Label which mixture is which and supply a key. Fe = S = Homogeneous (evenly distributed) Heterogeneous (not evenly distributed) 9. The apparatus to the right was used in lab. a. Which type of mixture can be separated using the apparatus shown? 1. salt and water 2. oil and water 3. sand and water 4. carbon dioxide gas and water b. Describe the procedure you would use to separate the mixture you chose in part a. Pour the sand and water mixture into the filter paper lining the funnel. The sand will stay on the top and the water will drain through. The sand must sit out to allow the water to completely evaporate and to separate the mixture completely. 8

9 Topic 6: Pure Substances 1. Which pair can be classified as pure chemical substances? (1) mixtures and solutions (2) elements and mixtures (3) compounds and solutions (4) compounds and elements Use the diagrams below to answer questions 2 5: (1) (2) (3) (4) 2. Which particle diagram is showing a sample where the particles are considered to be fixed in place, vibrating? (2) = solid 3. Why is Sample #1 considered a pure substance, even though there are two types of atoms involved? The atoms are chemically combined forming just one compound. Compounds are pure substances. 4. Which sample contains a diatomic element? 3 How do you know? It contains two of the same type of atom. 5. Which sample contains a diatomic compound? 4 How do you know? It contains two atoms that are not the same type. 9

10 Topic 7: Changes 1. Indicate whether the following is a chemical change (C), physical change (P), or neither. C a) a hydrogen balloon explodes P c) a puddle of water evaporates P b) snow melts P d) sand and salt mixture are separated 2. Which substance can be decomposed by chemical means? (1) aluminum (2) water (3) silicon (4) xenon 3. Which equation represents a physical change? (1) H2O(s) + heat H2O(l) (3) H2(g) + I2(g) + heat 2HI(g) (2) 2H2(g) + O2(g) 2H2O(g) + heat (4) N2(g) + 2O2(g) + heat 2NO2(g) 4. Heat is added to a sample of liquid water, starting at 80 C, until the entire sample is a gas at 120 C. This process, occurring at standard pressure, is represented by the balanced equation below. H2O(l) + heat H2O(g) Draw a particle diagram to represent at least five molecules of the product of this physical change at 120. C. 5. What is Conservation of Mass and how do you know when a chemical reaction shows conservation of mass/matter? Conservation of Mass/Matter means that no atoms can be created or destroyed in a reaction. You can check for this by counting the number of atoms before and after the arrow or by measuring the total mass before and after the chemical reaction. 6. Arsenic is often obtained by heating the ore arsenopyrite, FeAsS. The decomposition of FeAsS is represented by the balanced equation below. 125 kg 67.5kg + x When heated, a kilogram sample of arsenopyrite yields 67.5 kilograms of FeS. Determine the total mass of arsenic produced in this reaction. Conservation of mass tells us that mass cannot be created or destroyed during a chemical reaction so it should be equal on both sides of the equation. 125 kg = 67.5 kg + x As(g) = 57.5 kg kg kg 57.5 kg = x 10

11 Use the diagram below to answer questions #7-9: 7. Words for the change that is shown should read a) Two molecules of the element H2 and two molecules of the element Cl2 interacted physically and formed into four molecules of the compound HCl. b) Two atoms of the element H2 and two atoms of the element Cl2 interacted chemically and formed into four atoms of the compound HCl. c) Two molecules of the compound H2 and two molecules of the compound Cl2 interacted chemically and formed into four molecules of the compound HCl. d) Two molecules of the element H2 and two molecules of the element Cl2 interacted chemically and formed into four molecules of the compound HCl. 8. If = Cl and = H, then what is the composition of the box on the left, using particle symbols? 2 Cl2 (g) + 2 H2 (g) 9. Describe how you know that conservation of mass (particles) occurred during the change that the diagrams represent. Using chemical symbols is encouraged!! 2 Cl2 (g) + 2 H2 (g) 4HCl (g) 4 Cl on left/right 4 H on left/right There are the same number/type of atom on both sides of the equation (arrow). Answer questions #10-12 based on the following: The interaction between Na (s) and Cl2 (g) is described as follows: Sodium metal will react with chlorine gas in a spectacular, sparking reaction that produces the compound NaCl. This interaction can be described by the equation and the particle diagram below: Equation: 2 Na + Cl2 2 NaCl + heat and light Particle Diagram: In terms of the equation, explain how the Conservation of Mass is shown. There are 2 Na and 2 Cl on both sides of the arrow. (same number/type of particle on both sides) 11. In terms of the particle picture, explain how Conservation of Mass is shown. There are two dark circles and two light circles on both sides of the arrow. 12. Is the reaction between sodium and chlorine exothermic or endothermic? Tell how you know. The reaction is exothermic because heat is on the right side of the equation and therefore it is being given off as a product. 11