Chemistry 11–12 · Year 11
A spontaneous endothermic reaction: barium hydroxide octahydrate with ammonium chloride (teacher demonstration)
Module 4: Drivers of Reactions
Teacher-led demonstration
A teacher carries out this activity as a demonstration. Its materials, steps, variables, misconceptions and sources are not published on the open web, and neither is any result, control or note that states a number or an amount: tutors and administrators read them on the learning platform, with the safety card first. The idea, the hazards and the curriculum references are below.
Open the procedure on the learning platform (tutor or administrator sign-in)
School laboratory, not for home
In a school laboratory, with a teacher supervising, under the school's risk assessment. Not for home.
The idea
A reaction can run on its own while absorbing heat because the large increase in entropy (solids to a slush of ions, water and ammonia gas) outweighs the enthalpy cost.
Safety card
Setting: In a school laboratory, with a teacher supervising, under the school's risk assessment. Not for home.
Hazards
- barium hydroxide is corrosive and barium compounds are toxic
- ammonia gas is toxic and irritant
- ammonium chloride is harmful
- beaker cold enough to cause frost injury
Controls
At least one of them states a number or an amount, which may be part of the method, so the controls are shown with the method to tutors and administrators on the learning platform.
Note
It states a number or an amount, which may be part of the method, so it is shown with the method to tutors and administrators on the learning platform.
What you should see
It states a number or an amount, which may be part of the method, so it is shown with the method to tutors and administrators on the learning platform.
Curriculum references
The NSW syllabus outcomes and Australian Curriculum v9 codes this activity supports. They are references, not a verified or complete curriculum alignment.