[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?
-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.
To solve the given equation: [2.0 mol (-285.91 kJ/mol)] + [1.0 mole (0 kJ/mol)] - [1.0 mole (50.61 kJ/mol)], you need to perform the arithmetic operations step by step.
Let's break it down:
1. Multiply the number of moles by the energy value for each term:
- [2.0 mol * (-285.91 kJ/mol)] = -571.82 kJ
- [1.0 mol * (0 kJ/mol)] = 0 kJ
- [1.0 mol * (50.61 kJ/mol)] = -50.61 kJ
2. Add the calculated values:
- (-571.82 kJ) + (0 kJ) - (-50.61 kJ) = -571.82 kJ + 50.61 kJ = -521.21 kJ
Now, let's discuss the significant figures and units:
- The significant figures are determined based on the least number of significant figures present in the given values. In this case, all the given energy values have five significant figures. Therefore, the result should be rounded to five significant figures as well.
- Since all the given values are in kilojoules (kJ), the result should also be in kilojoules (kJ).
Therefore, the final answer with proper significant figures and units is -521.21 kJ to five significant figures.