<span>One theory that explains why scientific theories grow stronger over time is because more scientists study and work on the theory. Over time as the theory is studied in greater depth it becomes more accepted.</span>
<span>Hess' Law states that the enthalpy change in a reaction can be calculated from the enthalpy changes of reactions that, when combined, result in the desired reaction.
For example, to check the enthalpy change that occurs when benzene undergoes incomplete combustion to water and carbon monoxide is not an easy task, because the products invariably contain CO2. However, by combining the reactions of the complete combustion of benzene and the combustion of CO, you can get the reaction you want.
Reaction wanted: 2C6H6 + 9O2 → 12CO + 6H2O
Reactions provided: 2C6H6 + 15O2 → 12CO2 + 6H2O and 2CO + O2 → 2CO2, and their associated ΔH.
Rearrange the reactions so that, when they add up, they result in the wanted reaction.
2C6H6 + 15O2 → 12CO2 + 6H2O (leave as is; no changes to ΔH)
12CO2 → 12CO + 6O2 (reverse and multiply by 6; this changes the sign of ΔH and multiplies it by 6)
Added up, it will result in 2C6H6 + 9O2 → 12CO + 6H2O. Add up the ΔH values for the rearranged reactions to find ΔH for this particular reaction.</span>
HCH bond angle is ~110 degrees.
<span>Water soaks into it easily and during freeze-thaw cycles would be more likely to break apart because of the water freezing and thawing inside the rock. The water freezes and expands inside the rock, causing the surface to break off in flakes from the pressure of the expanding ice inside.</span>
Answer:
13 kJ
Explanation:
Use the following formula where Q is the Joules needed, m is the mass of the substance, c is the heat capacity, and ΔT is the change in temperature.
Q = mcΔT
The heat capacity of water is 4.186 J/g°C. The mass of water is 234 g. The change in temperature is 13.3°C.
Q = mcΔT
Q = (234 g)(4.186 J/g°C)(13.3°C)
Q = 13,027 J
Since the answer is in Joules, convert to kiloJoules.
13,027 J = 13.027 kJ ≈ 13 kJ
