To calculate the amount of heat released or absorbed in a chemical reaction, you need to use the equation ΔH = q/m, where ΔH is the heat change, q is the amount of heat, and m is the mass of the substance involved in the reaction.
Let's begin with the first question:
1. How much heat is released when 9.22 grams of glucose C6H12O6 reacts according to the following equation?
C6H12O6 + 6O2 --> 6CO2 + 6H2O ∆H = -2803 kJ
To find the heat released, we need to calculate q. The molar mass of glucose (C6H12O6) is:
6 carbon atoms * atomic mass of carbon (12.01 g/mol) +
12 hydrogen atoms * atomic mass of hydrogen (1.01 g/mol) +
6 oxygen atoms * atomic mass of oxygen (16.00 g/mol).
Molar mass of glucose = 6(12.01) + 12(1.01) + 6(16.00) = 180.18 g/mol.
Next, we need to calculate the moles of glucose:
moles = mass / molar mass = 9.22 g / 180.18 g/mol.
moles = 0.0512 mol.
According to the balanced equation, the molar ratio between glucose and heat release is 1:2803 kJ. Thus, we can calculate the heat released:
q = moles * ΔH = 0.0512 mol * (-2803 kJ/1 mol).
Therefore, the amount of heat released is -143.42 kJ.
Moving on to the second question:
2. How much heat is absorbed during photosynthesis when 9.22 grams of glucose C6H12O6 is produced?
6CO2 + 6H2O --> C6H12O6 + 6O2 ∆H = +2803 kJ
The approach to this question is similar to the first one, but now we are calculating the heat absorbed. Following the same calculations, we determine that the moles of glucose produced is the same (0.0512 mol).
Since the molar ratio between glucose and the heat change is 1:2803 kJ in the opposite direction, the heat absorbed is:
q = moles * ΔH = 0.0512 mol * (2803 kJ/1 mol).
Therefore, the amount of heat absorbed is +143.42 kJ.
Now, let's move to the third question:
3. How much heat is released when 147 grams of NO2(g) is dissolved in excess water?
3NO2 + H2O --> 2HNO3 + NO ∆H = -138 kJ
First, we need to convert the mass of NO2(g) to moles. To do this, we divide the given mass by the molar mass of NO2 (molar mass of nitrogen + 2 * molar mass of oxygen):
Molar mass of NO2 = 14.01 g/mol (atomic mass of nitrogen) + 2 * 16.00 g/mol (atomic mass of oxygen).
Molar mass of NO2 = 46.01 g/mol.
moles = mass / molar mass = 147 g / 46.01 g/mol.
moles = 3.196 mol.
Using the balanced equation, we see that the molar ratio of NO2 to the heat release is 3:1. Therefore, the heat released is:
q = moles * ΔH = 3.196 mol * (-138 kJ/3 mol).
Hence, the amount of heat released is -604.67 kJ.
Lastly, let's tackle the fourth question:
4. Calculate the heat released when 74.6 grams of SO2 reacts according to the following equation.
2SO2 + O2 --> 2SO3 ∆H = -99.1 kJ
Similar to previous calculations, first, convert the mass of SO2 to moles:
Molar mass of SO2 = 32.07 g/mol (atomic mass of sulfur) + 2 * 16.00 g/mol (atomic mass of oxygen).
Molar mass of SO2 = 64.07 g/mol.
moles = mass / molar mass = 74.6 g / 64.07 g/mol.
moles = 1.165 mol.
According to the balanced equation, the molar ratio between SO2 and the heat release is 2:1. Thus, the heat released is:
q = moles * ΔH = 1.165 mol * (-99.1 kJ/2 mol).
Therefore, the amount of heat released is -57.17 kJ.
Please note that the values have been rounded to two decimal places for clarity, but it's always advisable to keep more significant figures throughout the calculations.