Unit 1: Measurement & Matter

 Unit 1 exam on Wed. Oct. 1  Lab tomorrow: Tues. Sept. 30  Pre-lab quiz (online) due by tomorrow 8am

 1) 273K = __________ °C K = 0°C

 2) How many sig figs are in: sig figs Decimal Present Count from Pacific (left side)  disregard initial zeros

 3) How many sig figs are in: sig figs Decimal Absent Count from Atlantic (right side)  disregard initial zeros

 4) A metal block has the following dimensions: L = 0.5 cmW = 0.15 cmH = 0.25 c m How many sig figs should appear in the final answer for the volume of the metal block? 1 sig fig

 5) What are two ways to measure volume? 1)Water displacement 2)Multiplying dimensions (LxWxH)

 6) What is the density in g/cm 3 of a metal block that has a mass of 1000 mg and a volume of 10 cm 3 ? 1000 mg = 1 g D = 1 g / 10 cm 3 = 0.1 g/cm 3

 7) Will the metal block from the previous question (d= 0.1 g/cm 3 ) sink or float when placed in water? It will float when placed in water because its density is less than the density of water, 1.0 g/cm 3.

 8) A copper penny has a density of 8.9 g/cm 3 and a volume of 0.35 cm 3. What is the mass of the copper penny? Round your answer to the appropriate number of significant figures. m = d*v = 8.9 g/cm 3 x 0.35 cm 3 m = g  2 sig figs  3.1 g

 9) Calculate the percent error in the last problem (we calculated 3.1 g) if the accepted mass of a copper penny is 3.2 g. Round your answer to the appropriate number of significant figures. % error = ( )/3.2 * 100% % error = 3.125%  2 sig figs  3.1%

 10) Give one physical property and one chemical property of the element copper, Cu. Physical property = color; density; BP; MP (from Table S) Chemical property = ability to oxidize//rust

 11) What is one difference between a compound and a mixture?  Compounds are homogeneous  Mixtures can be both homogeneous & heterogeneous.  In a compound, the properties of the individual components are different when separated  In a mixture, the individual components retain their properties.  Mixtures can be physically separated.  Compounds cannot be physically separated.

 12) What is one difference between an element and a compound?  Elements cannot be broken down chemically.  Compounds can be broken down chemically.  Elements are made of atoms of the same element.  Compounds are atoms of different elements chemically bonded.

 13) What does (aq) represent? EX: NaCl(aq) Aqueous = NaCl(s) dissolved in H 2 O(l) AKA solution AKA homogeneous mixture

 14) How could you physically change a piece of paper? Crumple it; tear it; fold it; etc…

 15) How could you chemically change a piece of paper? Burn it

 16) Is the water cycle considered a chemical change or physical change? Explain. Physical change because the water undergoes changes in phases (or states) of matter. Therefore, the composition remains the same. H 2 O (s) ↔ H 2 O (l) ↔ H 2 O (g)

 17) Define the Law of Conservation of Mass & give an example. Mass is neither created nor destroyed. Examples vary…

 18) Which of the following represents a mixture? A. HCl (s) B. HCl (l) C. HCl (g) D. HCl (aq) D

 19) What is always the first step of the Scientific Method? Identify the problem or question to be answered.

 20) What is always the last step of the Scientific Method? Write a conclusion statement.

 21) How could you separate a mixture of salt water? Distill or evaporate the water.

 22) Explain the effectiveness of a distillation for a mixture of two substance with boiling points of 80°C and 90°C. A distillation would not be effective because the boiling points are too close together.

 23) You filter a mixture of oil and vinegar. What will pass through the filter? Both the oil & vinegar.

 24) You filter a mixture of mud (water and dirt). What will pass through the filter? Just the water

 25) You distill a mixture of acetone (BP=56°C) and water (BP=100°C). Which of the substances will distill first & be collected in the receiving flask? Acetone

TEST ON WED. 10/1

 Temperature conversions (K & °C)  Sig Figs  Sig Figs in calculations  Scientific Method – know the steps  Matter  Substances aka pure substances  Elements  Compounds  Mixture  Mixtures versus compounds  Solutions (aq)  Heterogeneous  Homogeneous  Physical property  Chemical property  Physical change  Chemical change  Law of Conservation of Mass  Mass, Volume, and Density calculations  Percent error calculations