Matter and EnergyMatter and Energy

Chapter 2 Section Reviews Chapter 2 Section Reviews

2-1 (pg 47 #1-10) 2-2 (pg 55 #1-11) 2-1 (pg 47 #1-10) 2-2 (pg 55 #1-11) 2-3 (pg 64 #1-12)2-3 (pg 64 #1-12)

2-1 (pg 47 #1-10)2-1 (pg 47 #1-10)

1.1. What is the difference between What is the difference between potential energy and kinetic energy? potential energy and kinetic energy? Both are the capacity to do work. Both are the capacity to do work. Kinetic energy is the energy an Kinetic energy is the energy an object has due to its motion. object has due to its motion. Potential energy is the energy of an Potential energy is the energy of an object that has the potential to move object that has the potential to move because of its position.because of its position.

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2.2. What is the difference between What is the difference between heat and temperature? heat and temperature? Heat is Heat is the total kinetic energy of the the total kinetic energy of the particles in a sample of matter. particles in a sample of matter. Temperature is a measure of the Temperature is a measure of the average kinetic energy of the average kinetic energy of the particles in an object.particles in an object.

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3.3. Explain what the equation Explain what the equation E=mcE=mc22 signifies? signifies? The equation The equation represents the amount of energy represents the amount of energy available when a quantity of available when a quantity of matter is changed completely matter is changed completely into energy.into energy.

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4.4. What energy changes are What energy changes are considered chemical energy? considered chemical energy? The potential energy changes The potential energy changes that result from the destruction that result from the destruction and formation of chemical bonds and formation of chemical bonds are considered chemical energy.are considered chemical energy.

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5.5. What is a system? What is a system? A system is A system is all of the components that are all of the components that are being studied at a given time.being studied at a given time.

6.6. Define Define specific heat capacityspecific heat capacity. . Specific heat capacity is the Specific heat capacity is the amount of heat required to raise amount of heat required to raise 1 gram of the substance by 1 K. 1 gram of the substance by 1 K.

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7.7. What happens in terms of heat What happens in terms of heat transfer when you hold a transfer when you hold a snowball in your hand? snowball in your hand? Heat Heat passes from your hand, which is passes from your hand, which is at a higher temperature, to the at a higher temperature, to the snowball, which is at a lower snowball, which is at a lower temperature.temperature.

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8.8. a) a) Which of the metals listed requires Which of the metals listed requires the most energy to raise its the most energy to raise its temperature by 1temperature by 1°°C?C? Aluminum.Aluminum.b) b) If energy is added at the same rate If energy is added at the same rate to containers all of the same mass to containers all of the same mass made of copper, chromium, and lead, made of copper, chromium, and lead, which container will show the which container will show the greatest rise in temperature after 10 greatest rise in temperature after 10 minutes?minutes? LeadLead

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9.9. Convert the following Celsius Convert the following Celsius temperatures to Kelvin temperatures to Kelvin temperatures? temperatures? a) 100a) 100°C = °C = 373K373Kb) 785°C = b) 785°C = 1058K1058Kc) 0°C = c) 0°C = 273K273Kd) -37°C = d) -37°C = 236K236K

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10.10. Convert the following Kelvin Convert the following Kelvin temperatures to Celsius temperatures to Celsius temperatures? temperatures? a) 273a) 273K = K = 0°C0°Cb) 1200K = b) 1200K = 927°C927°Cc) 0K = c) 0K = -273°C-273°Cd) 100K = d) 100K = -173°C-173°C

2-2 (pg 55 #1-11)2-2 (pg 55 #1-11)

1.1. What activities are part of the What activities are part of the scientific method? scientific method? **Refer to the Refer to the Scientific Method notes handout.Scientific Method notes handout.

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2.2. How does a hypothesis differ How does a hypothesis differ from a theory? from a theory? A hypothesis is a A hypothesis is a testable explanation for testable explanation for observations. A theory is also an observations. A theory is also an explanation of observations, but explanation of observations, but it is the result of repeated testing it is the result of repeated testing and revision of hypotheses.and revision of hypotheses.

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3.3. State the law of conservation of State the law of conservation of mass? mass? The total mass of the The total mass of the products of a reaction is the products of a reaction is the same as the total mass of the same as the total mass of the reactants.reactants.

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4.4. What is a scientific law, and What is a scientific law, and how does it differ from a theory? how does it differ from a theory? A scientific law reliably A scientific law reliably describes the observed behavior describes the observed behavior of the natural world but does not of the natural world but does not explain it. The theory explains explain it. The theory explains the observed behavior.the observed behavior.

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5.5. Name two chemical compounds Name two chemical compounds that were accidentally that were accidentally discovered, and describe what discovered, and describe what they are used for? they are used for? Penicillin – Penicillin – treat infections. Saccharine – treat infections. Saccharine – sugar substitute. sugar substitute.

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6.6. Why does a scientist include a Why does a scientist include a control in the design of an control in the design of an experiment? experiment? A control is used to A control is used to isolate the variable a scientist isolate the variable a scientist wants to study.wants to study.

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7.7. Give two reasons why scientists Give two reasons why scientists publish the results of their publish the results of their experiment. experiment. Research results are Research results are published so that researchers are published so that researchers are credited for their work and so credited for their work and so that other scientists can critique that other scientists can critique the results and attempt to the results and attempt to replicate them.replicate them.

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8.8. How do models help chemists How do models help chemists acquire knowledge about matter acquire knowledge about matter and energy? and energy? Models can be used Models can be used to make predictions about the to make predictions about the behavior of matter and energy.behavior of matter and energy.

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9.9. What variables would a chemist What variables would a chemist need to control when setting up an need to control when setting up an experiment to determine whether or experiment to determine whether or not a low temperature is required not a low temperature is required for TFE to form a polymer? for TFE to form a polymer? Ex: the Ex: the volume of the reaction vessel, the volume of the reaction vessel, the mass of the reactants, the pressure mass of the reactants, the pressure of the reaction system, and the of the reaction system, and the composition of the reaction mixture.composition of the reaction mixture.

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9.9. What variables would a chemist What variables would a chemist need to control when setting up an need to control when setting up an experiment to determine whether or experiment to determine whether or not a low temperature is required not a low temperature is required for TFE to form a polymer? for TFE to form a polymer? Ex: the Ex: the volume of the reaction vessel, the volume of the reaction vessel, the mass of the reactants, the pressure mass of the reactants, the pressure of the reaction system, and the of the reaction system, and the composition of the reaction mixture.composition of the reaction mixture.

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10.10. Describe what is needed for a Describe what is needed for a hypothesis to develop into a hypothesis to develop into a theory? theory? Usually, many Usually, many experiments followed by experiments followed by revision and refinement of the revision and refinement of the hypothesis are required.hypothesis are required.

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11.11. Why is there no single scientific Why is there no single scientific method? method? Scientists seldom Scientists seldom follow a strict series of steps in follow a strict series of steps in their work.their work.

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1.1. How does accuracy differ from How does accuracy differ from precision? precision? Accuracy indicates Accuracy indicates how close a measurement is to how close a measurement is to the true value. Precision the true value. Precision indicates how close repeated indicates how close repeated measurements are to each other.measurements are to each other.

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2.2. What do the significant figures What do the significant figures in a measurement indicate? in a measurement indicate? The The significant figures in a significant figures in a measurement are an indication measurement are an indication of the precision of the of the precision of the measurement.measurement.

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3.3. Explain the advantage of using Explain the advantage of using scientific notation? scientific notation? Scientific Scientific notation makes it easier to write notation makes it easier to write very large values and very small very large values and very small values.values.

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4.4. What is an exact value? Give an What is an exact value? Give an example. example. Counts of items and Counts of items and conversion factors are exact conversion factors are exact values. Ex: 1000mm = 1m.values. Ex: 1000mm = 1m.

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5.5. Describe a problem that may Describe a problem that may arise when you use a calculator arise when you use a calculator to compute an answer. to compute an answer. Calculators cannot make Calculators cannot make judgments about significant judgments about significant figures. Humans must do that. figures. Humans must do that. Therefore, calculator results Therefore, calculator results must be rounded as needed.must be rounded as needed.

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6.6. Why is a burette rather than a Why is a burette rather than a graduated cylinder used when graduated cylinder used when precise volumes are required in a precise volumes are required in a lab procedure? lab procedure? Graduated Graduated cylinders can measure only to cylinders can measure only to the nearest 0.1mL. Most burettes the nearest 0.1mL. Most burettes can measure to the nearest can measure to the nearest 0.01mL.0.01mL.

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7.7. If you measure the mass of liquid If you measure the mass of liquid as 11.50g and its volume as as 11.50g and its volume as 9.03mL, how many significant 9.03mL, how many significant figures should its density value figures should its density value have? have? The density value should The density value should have three significant figures have three significant figures because 9.03mL has only three because 9.03mL has only three significant figures.significant figures.

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8.8. How many significant figures How many significant figures are there in these expressions?are there in these expressions?a) 470km = a) 470km = 33b) 0.0980m = b) 0.0980m = 33c) 30.8900g = c) 30.8900g = 66d) 0.09709kg = d) 0.09709kg = 44

2-3 (pg 64 #1-12)2-3 (pg 64 #1-12)9.9. Perform the following calculations, and Perform the following calculations, and

express the answers in significant figures.express the answers in significant figures.

a) 32.89g + 14.21g = a) 32.89g + 14.21g = 47.10g47.10g

b) 34.09L – 1.230L = b) 34.09L – 1.230L = 32.86L32.86Lc) 3.45 x 10c) 3.45 x 1055g – 2.6 x 10g – 2.6 x 1033g= g= 3.424 x 3.424 x 101055ggd) 1.8940cm x 0.0651cm = d) 1.8940cm x 0.0651cm = 0.123cm0.123cm22

e) 24.897mi/0.8700h = e) 24.897mi/0.8700h = 28.62mi/h28.62mi/h

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10.10. Express the following calculations in the Express the following calculations in the proper number of significant figures. Use proper number of significant figures. Use scientific notation where appropriate.scientific notation where appropriate.

a) 129g/29.2mL = a) 129g/29.2mL = 4.42g/mL4.42g/mL

b)(1.551mm)(3.260mm)(4.9001mm) b)(1.551mm)(3.260mm)(4.9001mm) = = 24.78mm24.78mm33

c) 35,000kJ/0.250s = c) 35,000kJ/0.250s = 1.4 x 101.4 x 1055kJ/skJ/sd) 0.367L + 2.5L + 1.6004L = d) 0.367L + 2.5L + 1.6004L = 4.48L4.48L

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11.11. A chemical process produces A chemical process produces 653,550kJ of heat in 142.3 min. 653,550kJ of heat in 142.3 min. What is the rate of heat What is the rate of heat production in kJ/min? production in kJ/min? 4593kJ/min.4593kJ/min.

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12.12. Express the following quantities Express the following quantities in scientific notation.in scientific notation.a) 277,088,000,000,000 atoms = a) 277,088,000,000,000 atoms = 2.77088 x 102.77088 x 101414atomsatomsb) 0.000000000000839602g = b) 0.000000000000839602g = 8.39602 x 108.39602 x 10-13-13ggc) 700,004mm = c) 700,004mm = 7.00004 x 7.00004 x 101055mmmm