Chem+100+assignment+chapter+1

pdf

School

Alexander College *

*We aren’t endorsed by this school

Course

100

Subject

Chemistry

Date

Feb 20, 2024

Type

pdf

Pages

Uploaded by BarristerOysterPerson861

Chem 100 - Assignment chapter 1: Each answer counts for 4 points! Total point 20. Learning objective: • Discuss the reliability of a measurement: significant figures, precision and accuracy 1. Four different target shooters fired five shots at targets and their results are shown below. Which of the following statements best describes the precision and accur acy of each “marksman”? A B C D A) D is inaccurate and inprecise, C is precise. B) B is precise and accurate. C) A and D have similar precision, but A is more accurate. D) D is accurate and precise. Learning objective: • Perform dimensional analysis/unit conversion. Note: All your final answers must reflect the correct number of significant figures

2. Complete the “solution” part of the tables below, showing the con versions in the same format as in the example below. Example: a) Procedure for Solving Unit Conversion Problems Convert 1.76 miles to meters. Sort Begin by sorting the information in the problem into Given and Find . Given 1.76 mi Find m Strategize Devise a conceptual plan for the problem. Begin with the given quantity and symbolize each conversion step with an arrow. Below each arrow, write the appropriate conversion factor for that step. Focus on the units. The conceptual plan should end at the find quantity and its units. In these examples, the other information needed consists of relationships between the various units as shown. Conceptual Plan mi → km → m 1 km 0.6214 mi 1000 m 1 km Relationships Used 1 km = 0.6214 mi 1 km = 1000 m Solve Follow the conceptual plan. Begin with the given quantity and its units. Multiply by the appropriate conversion factor(s), cancelling units, to arrive at the find quantity. Round the answer to the correct number of significant figures. Remember that exact conversion factors do not limit significant figures. Solution

b) Additional Problem for Unit Conversion Involving Units Raised to a Power Calculate the number of cubic meters of concrete necessary to support a deck if each of 14 concrete piers require 4750 cubic inches. Sort Begin by sorting the information in the problem into Given and Find . Given 14 piers, 4750 in 3 Find m 3 Strategize Write a conceptual plan for the problem. Begin with the given information and devise a path to the information that you are asked to find. Notice that for cubic units, the conversion factors must be cubed. Conceptual Plan piers → in 3 → m 3 14 piers       3 1 m 39.37 in Relationships Used 1 m = 39.37 in 1 pier = 4750 in 3 Solve Follow the conceptual plan to solve the problem. Round the answer to three significant figures to reflect the three significant figures in the least precisely known quantity (4750). These conversion factors are all exact and therefore do not limit the number of significant figures. Solution c) Additional Problem for Density as a Conversion Factor An experimental automobile has a 100.0 liter fuel tank filled with ethanol. How many pounds does the fuel add to the mass of the car? Sort Begin by sorting the information in the problem into Given and Find . Given 100.0 L Find lb Strategize Devise a conceptual plan by beginning with the given quantity, in this case the volume in liters (L). The overall goal of this problem is to find the mass. You can convert between volume and mass using density (g/cm 3 ). However, you must first convert the volume to cm 3 . Once you have converted the volume to cm 3 , use the density to convert to g. Finally, convert g to lb. Conceptual Plan L → mL → cm 3 → g → lb 1000 mL 1 L 3 1 cm 1 mL 3 0.789 g 1 cm 1 lb 453.59 g Relationships Used 1000 mL = 1 L 1 mL = 1 cm 3 d (ethanol) = 0.7890 g/cm 3 1 lb = 453.59 g Solve Follow the conceptual plan to solve the problem. Round the answer to four significant figures to reflect the three significant figures in the density. Solution

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help

d) Additional Problem for Solving Problems Involving Equations What is the mass in grams of an ice cube that is 1.1 inches per side? Sort Begin by sorting the information in the problem into Given and Find . Given l = 1.1 in Find g Strategize Write a conceptual plan for the problem. Focus on the equation(s). The conceptual plan shows how the equation takes you from the given quantity (or quantities) to the find quantity. The conceptual plan may have several parts, involving other equations or required conversions. In these problems, you must use the geometrical relationships given in the problem as well as the definition of density. Conceptual Plan l → V V = l 3 in 3 → cm 3 → g       3 2.54 cm 1 in 3 0.917 g 1 cm Relationships Used V = l 3 [volume of a cube with a length of l ] 2.54 cm = 1 in d (ice) = 0.917 g/cm 3 Solve Follow the conceptual plan. Solve the equation(s) for the find quantity. Gather each of the quantities that must go into the equation in the correct units. (Convert to the correct units if necessary.) Substitute the numerical values and their units into the equation(s) and compute the answer. Round the answer to the correct number of significant figures. Solution