Answer:
1.2 × 10⁴ cal
Explanation:
Given data
- Initial temperature: 80 °C
We can calculate the heat released by the water (
) when it cools using the following expression.
where
c is the specific heat capacity of water (1 cal/g.°C)
According to the law of conservation of energy, the sum of the heat released by the water () and the heat absorbed by the reaction (
) is zero.
To calculate the average mass of the element, we take the summation of the product of the isotope and the percent abundance. In this case, the equation becomes 186.207=187*0.626+185*x where x is the percent abundance of 185. The answer is 0.374 or 37.4%. This can also be obtained by 100%-62.6%= 37.4%.
Answer:
Entropy increases
Explanation:
Entropy (S) is a measure of the degree of disorder. For a given substance - say water - across phases the following is true ...
S(ice) < S(water) << S(steam)
For a chemical process, entropy changes can be related to increasing or decreasing molar volumes of gas from reactant side of equation to product side of equation. That is ...
if molar volumes of gas increase, then entropy increases, and
if molar volumes of gas decrease, then entropy decreases.
For the reaction 2KClO₃(s) => 2KCl(s) + 3O₂(g)
molar volumes of gas => 0Vm* 0Vm 3Vm
*molar volumes (Vm) apply only to gas phase substances. Solids and liquids do not have molar volume.
Since the reaction produces 3 molar volumes of O₂(g) product vs 0 molar volumes of reactant, then the reaction is showing an increase in molar volumes of gas phase substances and its entropy is therefore increasing.
