Courses on Khan Academy are always 100% free. Start practicing—and saving your progress—now!

Our new middle school chemistry course launches in July 2025, but we couldn’t wait to share it! Videos like this one are rolling out over the next few months to give you a sneak peek of what’s to come. ��

Want to explore more? Check out the full middle school playlist here:
https://www.youtube.com/playlist?list=PLSQl0a2vh4HBnhjPgsJU2y1UhMwcYmb5u

Physical changes alter the appearance or state of matter without changing its identity. Whether bending copper wire, crushing salt, freezing water, or dissolving salt into water, the substances retain their original forms, like H₂O or NaCl. Understanding physical changes helps identify substances through properties like melting and boiling points, which are inherent and consistent across samples.

00:00 Introduction
00:33 Simple physical changes
01:26 Is phase change a physical change?
03:59 Is dissolving a physical change?
04:52 Summary

Khan Academy is a nonprofit organization with the mission of providing a free, world-class education for anyone, anywhere. We offer quizzes, questions, instructional videos, and articles on a range of academic subjects, including math, biology, chemistry, physics, history, economics, finance, grammar, preschool learning, and more. We provide teachers with tools and data so they can help their students develop the skills, habits, and mindsets for success in school and beyond. Khan Academy has been translated into dozens of languages, and 15 million people around the globe learn on Khan Academy every month. As a 501(c)(3) nonprofit organization, we would love your help!

Donate or volunteer today! Donate here: https://donate.khanacademy.org/give/419869/#!/donation/checkout

Volunteer here: https://www.khanacademy.org/contribute?utm_source=youtube&utm_medium=desc