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Physics Classroom is making strides to make our site accessible to everyone. Our site contains 6 navigation areas. The Primary, Secondary, and Page Level navigations have a screen reader version of their nav structure that allows using the left and right keys to navigate sibling navigation items, and up or down keys to navigate parent or child navigation items. The others can be navigated using tabs. The Primary Navigation handles the first 2 levels of site pages. The Secondary (which is not always available) handles the 3rd and 4th level of structure. The Page level navigation allows you to navigate the current page's headings quickly. The Header Navigation contains the Light/Dark Mode toggle, Search, Notifications and account login. The Breadcrumb Navigation contains the breadcrumb of the current page. If the current page has a breadcrumb, you can get to it by skipping to the content and tabbing in reverse (shift plus tab). The Footer Navigation contains links such as Privacy, Contact, about and terms. Some resources contain an Audio Player that can be activated by holding down the T key for 3 seconds, and then using K to pause and resume. While not every area of Physics Classroom is usable purely from keyboard and screen reader, we are committed to continue work on making this possible. If you have questions or need additional help, please use this link to contact us.

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Hess's Law

The Hess's Law Concept Builder provides learners an opportunity to apply Hess's Law in order to determine the enthalpy change of a reaction. The ∆H of two or three reactions is given. Their equations must be manipulated (reversed, multiply coefficients by a factor, etc.) and added to provide the target equation. Once accomplished, their ∆H values must be used to determine the ∆H for the target reaction. The Concept Builder consists of 27 questions organized into 9 Question Groups and spread across three difficulty levels.Question-specific help is provided for each of the 9 Question Groups. The built-in feedback makes this Concept Builder a perfect candidate for student practice or a classroom activity. And the use of the activity with our Task Tracker program allows teachers to view records of student progress.

Users are encouraged to open the Concept Builder and begin. There is no need for an activity sheet for this Concept Builder.

Learners and Instructors may also be interested in viewing the accompanying Notes page. Technical information, teaching suggestions, and related resources that complement this Interactive are provided on the View Notes.

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