Skip to main content
Ch.1 - Chemical Tools: Experimentation & Measurement
McMurry - Chemistry 8th Edition
McMurry8th EditionChemistryISBN: 9781292336145Not the one you use?Change textbook
All textbooksMcMurry 8th EditionCh.1 - Chemical Tools: Experimentation & MeasurementProblem 10
Chapter 1, Problem 10

An electron with a mass of 9.1 * 10-28 g is traveling at 1.8 * 107 m/s in an electron microscope. Calculate the kinetic energy of electron in units of joules, and report your answer in scientific notation. (LO 1.11) (a) 1.5 * 10-16 J (b) 1.6 * 10-20 J (c) 2.9 * 10-13 J (d) 2.9 * 10-10 J

Verified step by step guidance
1
Identify the formula for kinetic energy: \( KE = \frac{1}{2}mv^2 \), where \( m \) is mass and \( v \) is velocity.
Substitute the given values into the formula: \( m = 9.1 \times 10^{-28} \) g and \( v = 1.8 \times 10^7 \) m/s.
Convert the mass from grams to kilograms by multiplying by \( 10^{-3} \) since 1 g = 0.001 kg.
Calculate \( v^2 \) by squaring the velocity: \( (1.8 \times 10^7)^2 \).
Substitute the converted mass and calculated \( v^2 \) into the kinetic energy formula and simplify to find the kinetic energy in joules.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
1m
Was this helpful?

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Kinetic Energy Formula

The kinetic energy (KE) of an object can be calculated using the formula KE = 0.5 * m * v², where m is the mass and v is the velocity of the object. This formula shows that kinetic energy is directly proportional to the mass and the square of the velocity, meaning that even small increases in speed can lead to significant increases in kinetic energy.
Recommended video:
Guided course
02:27
Kinetic Energy Formulas

Units of Measurement

In physics, it is essential to use consistent units when performing calculations. Mass is often measured in kilograms (kg) in the SI system, while velocity is measured in meters per second (m/s). Kinetic energy is measured in joules (J), where 1 joule is equivalent to 1 kg·m²/s². Converting units correctly is crucial for accurate results.
Recommended video:
Guided course
02:52
Units of Radiation Measurement

Scientific Notation

Scientific notation is a way of expressing numbers that are too large or too small to be conveniently written in decimal form. It is represented as a product of a number between 1 and 10 and a power of ten, such as 1.5 * 10^-16. This notation simplifies calculations and comparisons, especially in fields like chemistry and physics where extreme values are common.
Recommended video:
Guided course
02:50
Standard Notation to Scientific Notation
Related Practice
Textbook Question
Perform the calculation, and report the answer to the correct number of significant figures. (LO 1.16)(a) 1.5 * 10^-4(b) 1.55 * 10^-4 (c) 1.547 * 10^-4(d) 1.5473 * 10^-4
10
views
Textbook Question
A 25.5 g sample of a metal was placed into water in a gradu-ated cylinder. The metal sank to the bottom, and the water level rose from 15.7 mL to 25.3 mL. What is the identity of the metal? (LO 1.9) (a) Tin (density = 7.31 g/cm3) (b) Lead (density = 11.34 g/cm3) (c) Silver (density = 10.49 g/cm3) (d) Aluminum (density = 2.64 g/cm3)
11
views
Textbook Question
Report the reading on the buret to the correct number of significant figures. (LO 1.15) (a) 1 mL (b) 1.4 mL (c) 1.40 mL (d) 1.400 mL
4
views
Textbook Question
A scientist uses an uncalibrated pH meter and measures the pH of a rainwater sample four times. A different pH meter was calibrated using several solutions with known pH. The true pH of the rain was found by the calibrated pH meter to be 5.12. What can be said about the level of accuracy and precision of the uncalibrated pH meter? (LO 1.14)(a) The uncalibrated pH meter is accurate and precise. (b) The uncalibrated pH meter is neither accurate nor precise. (c) The uncalibrated pH meter is accurate but not precise. (d) The uncalibrated pH meter is precise but not accurate.
3
views
Textbook Question
Consider 20 mL samples of the following liquids. Which sample has the largest mass? (LO 1.9) (a) Water (density = 1.0 g/mL) (b) Glycerol (density = 1.26 g/mL) (c) Ethanol (density = 0.79 g/mL) (d) Acetic acid (density = 1.05 g/mL
1
views
Textbook Question
The cylinder contains two liquids that do not mix with one another: water (density = 1.0 g/mL) and vegetable oil (density = 0.93 g/mL). Four different pieces of plastic are added to the cylinder. Which type of plastic is at the position indicated by the square object in the figure? (LO 1.10) (a) Polyvinyl chloride (density = 1.26 g/mL) (b) Polypropylene (density = 0.90 g/mL) (c) High-density polyethylene (density = 0.96 g/mL) (d) Polyethylene terephthalate (density = 1.38 g/mL)