<u><em>4.704625 kJ (or 4704.625 J) </em></u> is the amount of heat absorbed when the temperature of 75 grams of water increases from 20.°C to 35°C.
The measurement and calculation of the amounts of heat exchanged by a body or system is called calorimetry.
In this way, there is a direct proportionality relationship between heat and temperature. The constant of proportionality depends on the substance that constitutes the body as its mass, and the product of specific heat is produced by the body's mass. So, the equation that allows to calculate heat exchanges is:
Q = c * m * T
Where Q is the heat exchanged for a body of mass m, constituted by a specific heat substance c and where T is the temperature variation.
In this case:
The specific heat capacity (c) of water is 4,181 J / g°C
T=35°C - 20°C ⇒ T= 15°C
Being 1 kJ = 1000 J:
Finally, <u><em>4.704625 kJ (or 4704.625 J) is the amount of heat absorbed when the temperature of 75 grams of water increases from 20.°C to 35°C</em></u>
The detailed solution is found in the image attached. It is necessary to note that the oxidation half equation is multiplied by three to balance electron gain and loss. This is adequately shown in the image below. Inferences are only drawn from balanced redox reaction equation hence the first step is to balance the redox reaction equation.
The stability of atoms depends on whether or not their outer-most shell is filled with electrons. If the outer shell is filled, the atom is stable. ... In ionic bonds, atoms donate or receive electrons to achieve stability. In covalent bonds, atoms share electrons to achieve stability.
Citric acid exists as a power at room temperature, but can be crystallized from cold water. This can be considered it's " solid state, " but as I mentioned before this acid is a powder. Take a look at the attachment below. This is a citric acid present as a crystal;