Ch.7 - Quantum MechanicsWorksheetSee all chapters
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Ch.1 - Intro to General Chemistry
Ch.2 - Atoms & Elements
Ch.3 - Chemical Reactions
BONUS: Lab Techniques and Procedures
BONUS: Mathematical Operations and Functions
Ch.4 - Chemical Quantities & Aqueous Reactions
Ch.5 - Gases
Ch.6 - Thermochemistry
Ch.7 - Quantum Mechanics
Ch.8 - Periodic Properties of the Elements
Ch.9 - Bonding & Molecular Structure
Ch.10 - Molecular Shapes & Valence Bond Theory
Ch.11 - Liquids, Solids & Intermolecular Forces
Ch.12 - Solutions
Ch.13 - Chemical Kinetics
Ch.14 - Chemical Equilibrium
Ch.15 - Acid and Base Equilibrium
Ch.16 - Aqueous Equilibrium
Ch. 17 - Chemical Thermodynamics
Ch.18 - Electrochemistry
Ch.19 - Nuclear Chemistry
Ch.20 - Organic Chemistry
Ch.22 - Chemistry of the Nonmetals
Ch.23 - Transition Metals and Coordination Compounds

Solution: An electron has an uncertainty in its position of 190 pm. What is its uncertainty in its velocity?272 x 103 m/s 1.12 x 105 m/s 521 x 105 m/s 4.21 x 102 m/s 305 x 103 m/s


An electron has an uncertainty in its position of 190 pm. What is its uncertainty in its velocity?

  1. 272 x 103 m/s
  2. 1.12 x 105 m/s
  3. 521 x 105 m/s
  4. 4.21 x 102 m/s
  5. 305 x 103 m/s

We’re being asked to determine the uncertainty in the velocity of an electron with uncertainty in the position of 190 pm.

Recall that Heisenberg’s Uncertainty Principle states that we cannot accurately determine both the position and velocity of an electron. This means we can only know either one at any given time

Mathematically, this is expressed as:



h = Planck’s constant (6.626 × 10–34 kg  m2/s)

Δx = uncertainty in position (in m)

Δp = uncertainty in momentum (in kg  m/s)

Recall that momentum is expressed as:



m = mass

v = velocity

Since the mass of an electron is constant, only its velocity can be uncertain

This gives us:



m = mass (in kg)

Δv = uncertainty in velocity (in m/s)

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