[2.0 mol (-285.91 kJ/mol)] + [1.0 mole (0 kJ/mol)] - [1.0 mole (50.61 kJ/mol)] = ??? I came up with the answer of -622.43 but im not sure what the correct amount of significant figures would be and why? would 0 kj/mol be considered significant making the answer -600? what would the proper units be?

Question

[2.0 mol (-285.91 kJ/mol)] +  [1.0 mole (0 kJ/mol)]  - [1.0 mole (50.61 kJ/mol)] = ??? I came up with the answer of -622.43 but im not sure what the correct amount of significant figures would be and why? would 0 kj/mol be considered significant making the answer -600? what would the proper units be?

DrBob222 · Answer

-600 has 1 significant figure(s.f.); i.e., the 6.
The first multiplication has 2 s.f. for the answer since 2.0 has only 2. The second has 2 s.f. since 1.0 has only 2. So the answer must have 2 s.f.. I would make that -622.43 kJ round to -6.2E2 kJ.