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How do you calculate enthalpy change of formation from combustion?
To calculate the enthalpy change of formation from combustion, you can use Hess's law, which states that the total enthalpy change for a reaction is the sum of the enthalpy changes for individual steps. First, determine the enthalpy change for the combustion reaction using a calorimeter or from standard enthalpy values. Then, apply the equation: ΔH_f = ΔH_combustion + Σ(ΔH_f of products) - Σ(ΔH_f of reactants), where ΔH_f is the standard enthalpy of formation. This allows you to derive the enthalpy of formation for the desired compound based on its combustion data.
How do you determine whether a reaction is spontaneous or non spontaneous?
The first of two factors that determine whether a reaction is spontaneous or non-spontaneous is entropy. The second is energy. For a reaction to be spontaneous, it must have both of these factors.
When the speed at which a reactant will change to product is proportional?
Perhaps you are referring to a first order reaction.
What is the relationship between enthalpy of atomisation of hydrogen and the bond dissociation enthalpy of the H-H bond?
the enthalpy of atomisation of hydrogen is equal and (in principle) identical to the bond dissociation enthalpy of the H-H bond. However, IF the first is measured by calorimetry and the second by spectrometry there might be a systematic difference.
How much energy is required to decompose 765 g of PCl3 in 4PCl3---P4 plus 6Cl2?
The balanced chemical equation is 4PCl3 → P4 + 6Cl2. The molar mass of PCl3 is 137.33 g/mol. To calculate the energy required, first find the moles of PCl3 (765 g / 137.33 g/mol), then use the stoichiometry from the balanced equation to convert moles of PCl3 to moles of P4, and finally use the enthalpy values for each reaction to determine the total energy required. The enthalpy values for each reaction can then be multiplied by the number of moles of each substance in the reaction to find the total energy required for the reaction.
How do you solve Hess's law problems?
write out the balanced equation that you need then write out formation equations (2-4) that will give you those reactants and products. manipulate the equations by reversing them or multiplying or dividing by whatever number. until you have what you need for the original equation. whatever you do to the equation, do it to the enthalpy for that equation. everything should add or cancel until you have the equation needed and you can add the enthalpies to get the enthalpy for that equation
When 1.00 mole of NH4NO3 dissolves in water the enthalpy change is ΔH 25.7 kJ. What is the enthalpy change if 17.5 grams of NH4NO3 are dissolved in water?
To find the enthalpy change for 17.5 grams of NH4NO3, we first calculate the moles of NH4NO3 in 17.5 grams using its molar mass (80.052 g/mol). Next, we use the molar enthalpy change (25.7 kJ/mol) to find the enthalpy change for 17.5 grams, which is 3.57 kJ.
What is the relationship between adiabatic expansion and enthalpy change in a thermodynamic system?
During adiabatic expansion in a thermodynamic system, there is no heat exchange with the surroundings. This leads to a change in enthalpy, which is the total heat content of the system. The enthalpy change during adiabatic expansion is related to the work done by the system and can be calculated using the first law of thermodynamics.
Which of the following is a statement of Hess's law?
All the reactions in a path are added together.
How can an unknown H be determined using hess's law?
To use Hess Law, one simply uses the known equations and their respective ∆H values, rearranges them as necessary to arrive at the target equation (unknown ∆H) and then adds the ∆H values to obtain the value for the target equation. This is possible because Hess Law applies to state functions which are independent of the path.
What is a good sentence using the word enthalpy?
The first is the comparatively very high lattice enthalpy of the solid fluoride.
What does enthalpy of solution mean?
Enthalpy of solution describes the net change in heat when a solute is dissolved in a solvent. Specifically, the standard enthalpy of solution is the heat change when one mole of solute is completely dissolved in a solvent to form a solution concentration of 1 mol per dm3 under standard conditions. The net change in heat can be broken down into the sum of two heats. First, the solute crystals must break from their lattice. This is known as the lattice enthalpy and its reversal is typically endothermic. Second, the ions are solvated (or hydrated in the case of aqueous solutions), which is typically an exothermic step. Depending on the magnitude of each of these factors, the sum can lead to a positive or negative enthalpy of solution.
Is hydrochloric acid and calcium carbonate a first order reaction?
No, the reaction between hydrochloric acid and calcium carbonate is not a first order reaction. It is a decomposition reaction where the rate of reaction will not be constant as the concentration of the reactants change over time.
Why is the enthalpy of sublimation is equal to the sum of enthalpy of fusion and enthalpy of vaporization?
Enthalpy is a state function, and to a first approximation does not depend on temperature. So the change in enthalpy to go from solid to a gas directly (sublimation) at some temperature is equal to the sum of the enthalpies associated with going from a solid to a liquid (fusion) and going from a liquid to a gas (vaporization) at other temperatures.
Does energy change in a chemical reaction?
yes it does i didnt know that at first but it does
How do you determine whether a reaction is spontaneous or non spontaneous?
The first of two factors that determine whether a reaction is spontaneous or non-spontaneous is entropy. The second is energy. For a reaction to be spontaneous, it must have both of these factors.
Is the ionization enthalpy of the first two elements of isotopes same?
Ionization enthalpy of isotopes should be theoretically the same.But the recorded values aren't equal..nobody knows why..
