What does Hess's law say about the enthalpy of a reaction?
According to the law, a reaction's total enthalpy change occurs regardless of how many steps are involved in the process.
Stated differently, if a chemical change occurs through multiple pathways, the total enthalpy change remains constant, irrespective of the pathway used (as long as the starting and ending conditions remain the same).
When a reaction cannot be measured directly, Hess' law allows the enthalpy change (ΔH) to be calculated. This is done by applying previously determined values for the enthalpies of formation to basic algebraic operations based on the chemical equation of reactions.
A net equation, also called an overall equation, is created when chemical equations are added together. The enthalpy change for the net equation is obtained if the enthalpy change for each equation is known.
AN EXAMPLE
Resolution
Put down the equation you are aiming for, the target equation.
CO2(g) + 2SO2(g) → CS₂(l) + 2O₂(g)
Commence with equation 3, which includes the target's first compound (CS₂).
To move the CS₂ to the left, we need to flip equation 3 and its ΔH, which yields equation A below.
We now remove C(s) and S(s) one at a time. Since C(s) is present in Equation 1, we express it as Equation B below.
The target equation is then obtained by adding equations A, B, and C, and canceling terms that appear on opposite sides of the reaction arrows.
By signing up, you agree to our Terms of Service and Privacy Policy
Hess's law states that the total enthalpy change for a chemical reaction is the same, regardless of the number of steps taken to reach the final state. In other words, the overall enthalpy change is independent of the pathway and depends only on the initial and final states of the system.
By signing up, you agree to our Terms of Service and Privacy Policy
When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.
When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.
When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.
When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.
- How much heat i released to the environment as 245 g of steam at 140°C is cooled to -15°C?
- How many joules are needed to boil 59.8 g of ethanol if the heat of vaporization is 854 J/g?
- How can I explain exothermic reactions in terms of bond breaking?
- If the heat of reaction is written on the reactant side of a chemical equation, what does that indicate about the reaction?
- What conditions are spontaneous processes trying to satisfy?
- 98% accuracy study help
- Covers math, physics, chemistry, biology, and more
- Step-by-step, in-depth guides
- Readily available 24/7