(1) Why are fractional coefficients permitted in a balanced thermochemical equation?
In thermochemical reactions, only small amounts of matter are considered.
If fractional coefficients were not used, the scale of the reaction would be excessively large.
Fractional coefficients are permitted because the enthalpy change for the reaction is dependent on the amount of matter present.
Fractional coefficients are permitted in order to have the smallest possible set of coefficients for a given reaction.
Fractional coefficients are permitted because the enthalpy change for the reaction is independent of the amount of matter present.
If a thermochemical equation has a coefficient of 1/2 for a formula, it signifies that----?-------.
(2) A body of water with a mass of 732 g changed in temperature from 24.62 to 19.47 °C (Its specific heat is 4.184 J·g-1·K-1).
What would have to be done to cause such a change ? ------?---
How much energy (in kilojoules) is involved in this change?
----?-----kJ
(1) Why are fractional coefficients permitted in a balanced thermochemical equation?
In thermochemical reactions, only small amounts of matter are considered.
If fractional coefficients were not used, the scale of the reaction would be excessively large.
Fractional coefficients are permitted because the enthalpy change for the reaction is dependent on the amount of matter present.
Fractional coefficients are permitted in order to have the smallest possible set of coefficients for a given reaction. I think this is the one you want.
Fractional coefficients are permitted because the enthalpy change for the reaction is independent of the amount of matter present.
If a thermochemical equation has a coefficient of 1/2 for a formula, it signifies that----?-------.
(2) A body of water with a mass of 732 g changed in temperature from 24.62 to 19.47 °C (Its specific heat is 4.184 J·g-1·K-1).
What would have to be done to cause such a change ? ------?---
How much energy (in kilojoules) is involved in this change?
----?-----kJ
I would need to be cooled but that may be obvious
Second part:
mass x specific heat x delta T = q.
It would need .....
(1) If a thermochemical equation has a coefficient of 1/2 for a formula, it signifies that the reaction is trying to be half-hearted about it. It's like saying, "I'll only put in half the effort, but I still want the reaction to work!" It's a scientific way of being lazy.
(2) To cause such a change in temperature, you would need to give the body of water a nice vacation somewhere colder. Maybe send it on a trip to Antarctica or put it in a cooler with some ice packs. Basically, you need to remove heat from the water to make it cool down.
As for the amount of energy involved in this change, it's like asking how much energy it takes for a clown to make people laugh. It's impossible to measure in straightforward terms. But if you insist, you can calculate it using the formula: energy = mass x specific heat x temperature change. Happy math-ing!
(1) Fractional coefficients are permitted in a balanced thermochemical equation because the enthalpy change for a reaction is dependent on the amount of matter present. Thermochemical equations represent the amount of energy involved in a reaction, and this energy is proportional to the quantity of matter that is reacting. Fractional coefficients allow us to represent reactions that involve fractional amounts of substances, such as when a reaction occurs in a non-stoichiometric ratio or when a reaction involves a partial reaction. It is important to note that fractional coefficients should still be simplified to their lowest whole-number ratio whenever possible.
If a thermochemical equation has a coefficient of 1/2 for a formula, it signifies that the reaction only occurs with half of the stoichiometric amount of that substance, which could be due to various factors including the reaction conditions or the availability of reactants.
(2) To cause the change in temperature of the water, some form of energy transfer is required. In this case, the energy transfer is in the form of heat. To increase the temperature of the water, heat would need to be added to it, and to decrease the temperature, heat would need to be removed.
The amount of energy involved in this change can be calculated using the formula:
Energy (in Joules) = mass (in grams) × specific heat (in J·g-1·K-1) × change in temperature (in Kelvin)
First, convert the temperature change from Celsius to Kelvin by adding 273.15 to each temperature:
Initial temperature = 24.62 °C + 273.15 = 297.77 K
Final temperature = 19.47 °C + 273.15 = 292.62 K
Now, substitute the values into the formula:
Energy (in Joules) = 732 g × 4.184 J·g-1·K-1 × (292.62 K - 297.77 K)
Simplify the equation:
Energy (in Joules) = -Fel3028.058 J
To convert this value to kilojoules, divide by 1000:
Energy (in kilojoules) = -Fel3028.058 J / 1000 = -Fel3.028058 kJ
The negative sign indicates that heat was lost by the water, as its temperature decreased.