In photosynthesis, plants form glucose and oxygen from carbon dioxide and water.
Calculate Delta S at 15 degrees celsius.
Delta H = 2800 Kj
Delta S = -260 J
Delta Grxn = 2800-(15+273)(-260/1000)
= 2874.88
Non-Spontaneous
2800
how did you get this? I know its the right answer I just don't know how you got it
To calculate ΔS (change in entropy) at a given temperature, you need to know the initial and final states of the substances involved. In this case, we are considering photosynthesis in plants, where carbon dioxide (CO2) and water (H2O) are converted into glucose (C6H12O6) and oxygen (O2) as represented by the following chemical equation:
6CO2 + 6H2O → C6H12O6 + 6O2
To calculate the change in entropy (ΔS) for this reaction at 15 degrees Celsius, we need to consider the entropy changes of the reactants and the products.
1. Determine the standard molar entropy values (S°) for each compound involved in the reaction. These values can be found in thermodynamic tables or online databases. Here are some approximate values at 298 K (25 degrees Celsius) in units of J/(mol·K):
- CO2: 213.6 J/(mol·K)
- H2O (liquid): 69.9 J/(mol·K)
- Glucose (C6H12O6): 213.0 J/(mol·K)
- O2: 205.0 J/(mol·K)
2. Calculate the ΔS for the reactants by multiplying the number of moles of each compound by its respective entropy value (S°). In this case, since the balanced equation shows coefficients of 6 for each compound, we can assume one mole of each. Therefore:
ΔS reactants = (6 mol CO2)(213.6 J/(mol·K)) + (6 mol H2O)(69.9 J/(mol·K))
3. Calculate the ΔS for the products using the same approach:
ΔS products = (1 mol C6H12O6)(213.0 J/(mol·K)) + (6 mol O2)(205.0 J/(mol·K))
4. Calculate the ΔS for the reaction by subtracting the sum of the reactants' entropies from the sum of the products' entropies:
ΔS = ΔS products - ΔS reactants
Note: The above calculations assume ideal behavior for simplicity. In reality, the values may slightly deviate due to factors such as temperature and pressure variations.
Keep in mind that the above values are for standard states at 298 K, so if you specifically need the ΔS at 15 degrees Celsius, you might need to consider the temperature dependence of entropy and adjust the values accordingly using thermodynamic equations or tables that provide the temperature dependence information.