Answer : The enthalpy change of reaction is -23.9 kJ
Explanation :
According to Hess’s law of constant heat summation, the heat absorbed or evolved in a given chemical equation is the same whether the process occurs in one step or several steps.
According to this law, the chemical equation can be treated as ordinary algebraic expression and can be added or subtracted to yield the required equation. That means the enthalpy change of the overall reaction is the sum of the enthalpy changes of the intermediate reactions.
The given final reaction is,
The intermediate balanced chemical reaction will be,
(1)
(2)
First we will reverse the reaction 1 and multiply equation 2 by 3 then adding both the equation, we get :
(1)
(2)
The expression for final enthalpy is,
Therefore, the enthalpy change of reaction is -23.9 kJ
Answer : The initial mass of the sample is, 31.9 mg
Explanation :
Half-life = 4 days
First we have to calculate the rate constant, we use the formula :
Now we have to calculate the initial mass of sample.
Expression for rate law for first order kinetics is given by:
where,
k = rate constant =
t = time passed by the sample = 12 days
a = initial amount of the reactant = ?
a - x = amount left after decay process = 4 mg
Now put all the given values in above equation, we get
Therefore, the initial mass of the sample is, 31.9 mg
Answer:
carbohydrates, lipids, proteins, and nucleic acids.
Explanation:
Carbohydrates serve several key functions in your body. They provide you with energy for daily tasks and are the primary fuel source for your brain's high energy demands.
The functions of lipids include storing energy, signaling, and acting as structural components of cell membranes. Lipids have applications in the cosmetic and food industries as well as in nanotechnology.
Protein has many roles in your body. It helps repair and build your body's tissues, allows metabolic reactions to take place and coordinates bodily functions. In addition to providing your body with a structural framework, proteins also maintain proper pH and fluid balance.
The functions of nucleic acids have to do with the storage and expression of genetic information. Deoxyribonucleic acid (DNA) encodes the information the cell needs to make proteins. A related type of nucleic acid, called ribonucleic acid (RNA), comes in different molecular forms that participate in protein synthesis.